i* 1 "fa Division of Agricultural Sciences UNIVERSITY OF CALIFORNIA *infaf- PAUL F. KNOWLES MILTON D. MILLER CALIFORNIA AGRICULTURAL Experiment Station Extension Service CIRCULAR 532 % Safflower plant. The heads are at various stages o£ develop- ment, extending the flowering period over a long time. THE AUTHORS: Because information on safflower has been developed by many persons represent- ing several departments within the I niversity of California and USDA, this circular lias several authors. Paul F. Knowles, Professor of Agronomy and Agronomist in the Experi- ment Station, and Milton D. Miller, Extension Agronomist, Department of Agronomy, Davis, developed the general outline and wrote the parts not listed below . D. W. Henderson, Department of Irrigation, Davis. Section on irrigation Chester L. Foy, Department of Botany, Davis. Section on weed control Elmer C. Carlson, Department of Entomology and Parasitology, Davis. Section on insects J. M. Klisiewicz, (USDA), Department of Plant Pathology. Section on diseases John R. Goss, L. G. Jones, and Roydon T. Edwards, Department of Agricultural Engineering, Agricultural Extension Service and Agronomy Department, Davis, respectively. Section on harvest January, 1965 Safflower, one of the world's oldest crops is relatively new to American agri- culture. For centuries its culture was » confined to regions of India, other areas of Asia, Africa, and Europe, where the flowers were used as a source of dye for clothing and food. Synthetic dyes have now largely replaced it, though it is still ► grown in the Old World as a substitute for, or an adulterant of, saffron. India has grown safBower as an oil crop for >, probably more than 100 years; it still has the largest area of production. In India safflower oil is preferred in cook- The earliest reference to safflower in _, the United States comes from a 1899- 1901 substation research report of the * University of California. The report from the Southern California Substation in Chino Valley concludes with the state- »► ment "It: (safBower) thrives over a large part of California, and is of very easy r culture." During the period 1930 to 1940 seri- ous attempts were made to establish saf- flower commercially in the U. S. Great Plains area, but varieties available then were too low in oil to be of much inter- > est to oilseed processors. The develop- ment of "Nebraska" varieties (N-l to 4 N-10 and N-852) in the next decade, some of them having oil contents up to 36 per cent, made safflower a promising crop. It did not succeed at first in the Great Plains states. Following its com- mercial development in California it has been grown in Kansas, Nebraska, and Montana, and to a lesser extent in adja- cent states ; a total of about 150,000 acres was grown in that area in 1963. Arizona grew about 60,000 acres during the same year. Attempts have been made to develop safflower commercially in other coun- tries. Canada, Australia, Turkey, and Israel have grown it from time to time during the last 15 years with variable success. Currently the effort is being in- tensified. An insect, the safflower fly, destroyed a successful commercial devel- opment in France which began in 1943. Safflower was 15 years old in 1964 as a commercial crop in California. While its commercial development did not be- gin in this state, its success here has firmly established it as a new crop in American agriculture. These years have witnessed marked changes in the areas and patterns of production. They have brought with them a valuable accumula- tion of new knowledge of safflower pro- duction. Some of it has been obtained from public and private research and some from the hard school of grower and industry experience. This circular con- tains a summary of the information avail- able now. CONTENTS PAGE Description of the plant 4 Insects affecting safflower 25 How the plant develops 6 Diseases of safflower 33 Varieties grown in California 7 When and how to harvest 37 Growth requirements 8 Upward trend in yield 45 Cultural practices 11 Safflower products and by-products . .46 Irrigation 18 Some economic considerations 49 Weed control 20 Two weedy species of safflower 50 [3] SAFFLOWER DESCRIPTION OF THE PLANT Safflower (Carthamus tinctorius L.) is a winter annual that belongs to the thistle family The coarse stems of safflower reach a height of 2 to 5 feet, depending on the planting date — -late planting tends to re- sult in short plants. The plant produces many branches with heads at their ends. Each head, as is true of other thistles, consists of numerous flowers, and each flower potentially produces a single seed. Each head may produce from 20 to 100 seeds. The flower color varies with vari- ety, from red through orange and yellow to white. The seeds of present California varieties are white, and shaped like small sunflower seeds. Potential new varieties have grayish, brown or striped seeds. Seeds from two commercial varieties have the following characteristics (data from the USDA Western Utilization Re- search and Development Div. Albany) : Variety Moisture Oil Protein Gila US- 10 per cent 4.6 4.7 36.5 34.4 16.9 17.9 The remainder of the seeds consists of fibrous constituents, carbohydrates, and ash. The hull content of these varieties is about 37.5 per cent. Safflower varieties grown in California average about 36 per cent oil and 15 per cent protein. Varieties available in future years no doubt will average about 40 per cent oil content or more. Weight per bushel varies from 39 to 46 pounds, depending upon conditions of growth and variety. Present commercial varieties of saf- Safflower seeds: Longitudinal section below; exterior view above, US-10 on left, and Gila on right. The tough hull surrounding the embryo contains neither oil nor protein. Enlarged 5 times. [4] flower have spines on the leaves, and modified leaves associated with seed heads. The spines do not develop until the plants form heads. Most farmers do not consider spines a serious handicap in growing the crop. Much effort has been spent on developing spineless varieties, but thus far all such varieties have had a lower oil content or a lower yield than spiny varieties. However, productive spineless varieties are likely to be com- mercially available in the future. Cross section of head. Left: in full bloom; right: about 20 days later, head approaches maturity. About actual size. as [5] HOW THE PLANT DEVELOPS The seeds require temperatures above 40° F for germina- tion, and germinate quickly at temperatures near 60° F Germination and development of the seedling at minimum germination tem- peratures are very slow; it may take up to three weeks for the seedling to appear above the surface of the soil during cold weather. During late spring, germina- tion may proceed so rapidly that seed- lings appear three to four days after planting. After the seedlings emerge they re- main close to the ground. In the begin- ning they produce numerous leaves at the ground level, but no long stems. When sown in late fall (October or November), the plants may remain low for two or three months, but when sown in late spring (April or May) this stage may last less than four weeks. At Davis stem growth starts the latter part of March in safflower sown during winter or early spring, and about the end of April when sown the first part of March. In the San Joaquin Valley and in southern Cali- fornia stem growth begins in early March if the crop is planted in Decem- ber or January. The stem begins to grow when the temperature gets warm and the days become longer. Branching begins from the central woody stem when the plant is 8 to 15 inches tall. Depending on date of plant- ing, safflower reaches its full height of from 18 inches to 5 feet at the time it flowers. Present varieties are all about the same average height at maturity. Each central stem branches to form one to five or more flower heads. Wide plant spacing favors branching. Buds open into blossoms within four to five weeks after they appear. Individual seeds are physiologically mature in about 25 days after flowering. Within a head, the flowering and maturing of individual florets and seeds may range up to 7 days. On an average, a field is ready for har- vesting about 35 to 40 days after the peak of flowering. The early rosette or semidormant pe- riod is critical because weeds or volun- teer grain may grow ahead of the saf- flower and seriously reduce yields. This is particularly true of fall or very early spring plantings in northern California, where rains frequently prevent cultiva- tion to control rapidly growing weeds. In contrast to its slow start, safflower grows rapidly after the stems begin to elongate. In a good stand, and if the crop is kept relatively free of weeds until the stems begin to grow, weed competition usually will not be serious because the safflower generally shades out the weeds. A second critical stage in development may occur in some years after flowering, when plants fail to produce a satisfac- tory seed crop on large vigorous plants. This may be caused by insufficient soil moisture, as for instance under dry-land farming when winter rainfall is low and the previous crop has exhausted the soil moisture. Hot dry weather at flowering may also cause seed set failure. Depth of tap root penetration has a bearing on the behavior of the plant. Saf- flower roots have been found to a depth of 12 feet at Davis. Experiments by the Department of Irrigation of the Univer- sity of California at Davis have shown safflower depleting water from 9 feet deep in permeable soil. Despite its thistle-like characteristics, cultivated safflower has not become a weed problem in California. Because of its slow early growth, it cannot compete in a mixed stand either with wild or do- mestic plants. Like most cultivated crops, [6 seeds on the ground after harvest will germinate readily with fall rains or with a preirrigation, but seedlings are easily killed by frost, cultivation and 2,4-D. Saf- flower does not persist at the margins of fields. VARIETIES GROWN IN CALIFORNIA Gila and US-10 are the main publicly available varieties of California Gila, a safflower variety developed jointly by D. D. Rubis of the Arizona Agricul- tural Experiment Station, and C. A. Thomas of the U. S. Department of Agri- culture, is the most important variety in California. It was developed from a cross of N-10 and Western Oilseeds 14, back- crossed once to N-10. US-10, a variety developed by C. A. Thomas, has the same parentage as Gila, but was back- crossed six times to N-10. US-10 and Gila are very similar in appearance, but US- 10 has larger seed, and uniformly yellow flowers. Gila has mostly orange flowers, and some that are yellow and a few that are white. The oil content of Gila is 1 to 3 per cent higher than US-10, and this is the main reason for its popularity. US-10 has slightly more resistance to Phytopthora root rot than Gila, and both have considerably more resistance than N-10. Varieties no longer grown in Califor- nia are N-852, an introduction from Sudan; N-10, a selection from N-852; and N-6. All of these were developed by C. E. Claassen when he was at the Ne- braska Agricultural Experiment Station. While using the above varieties, the commercial companies also have devel- oped their own varieties. Information on these and other potential new releases of private lines may be obtained from the companies developing them. Two developments may change the variety situation in the next few years. DISTRUBITION OF SAFFLOWER PLANTED ACREAGE IN CALIFORNIA (Based on California Crop and Livestock Reporting Service Reports, industry data and reports by county agricultural commissioners.) Year Acreage Sacramento Valley San Joaquin Valley Other areas Total 1950 300 9,220 34,179 43,375 27,646 51,927 82,983 69,000 80,000 139,000 158,900 168,000 184,000 195,000 18,250 5,108 4,131 728 1,400 880 845 5.500 5,500 7,500 15,000 40,000 85,000 113,000 4,450 2,672 3,690 1,897 2,954 1,193 2,172 1,500 1,500 1,500 2,100 3,000 5,000 6,000 23,000 1951 17,000 1952 42,000 1953 46,000 1954 32,000 1955 54,000 1956 86,000 1957 76,000 1958 87,000 1959 148,000 1960 176,000 1961 211.000 1962 274 000 1963 314 000 [7 One is the development of varieties with very thin hulls. One type with thin hulls has been termed striped because the hull of the seed has alternating white and brown stripes. A second type has paper- thin hulls, grayish or brownish in color — it is termed thin-hull. Present thin-hull types have weak stems and branches, poor pollen production, and relatively low seed yield. With less hull in these types, the whole seed oil content is above 40, and sometimes above 45 per cent. Likewise, with less hull, the protein content will increase from the present level of 12 to 15 per cent up to as high as 21 per cent. Another likely development is hybrid varieties. In the production of experi- mental hybrids the thin-hull types have been used. Because these types produce little pollen (actually they produce pol- len, but fail to release it) they may be used as the female parent in the produc- * tion of a hybrid variety. The thin-hull lint 1 produces enough pollen to reproduce itself under isolation, but not enough to * interfere with the production of crosses in the presence of the male parent. The male parent may be any variety that pro- duces abundant pollen. Since safflower pollen is not wind-transmitted, bees or 4 other insects must be present in abun- dance. One problem currently facing the safflower breeder is to find two parents that will "nick" together to produce a hybrid variety that is more than 10 per *♦ cent higher than normal varieties in yield, above 40 per cent in oil, and eco- nomical from the standpoint of seed pro- duction. GROWTH REQUIREMENTS Atmospheric moisture and soil moisture are critical The minimum growing season for saf- flower is about 120 days. This is true in California if the crop is sown in May or June. Fall plantings will require more than 200 days. At Davis when safflower is planted at intervals from November to March, all plantings will mature over a range of about 10 days in early August. Plant growth depends on climate, water, and soil. Climate Atmospheric moisture. Above- ground parts of the safflower plants are sensitive to atmospheric moisture, pri- marily because it may make them more susceptible to diseases. Only in early stages does safflower appear to be quite tolerant of high atmospheric humidities. After the bud stage, prolonged rain or [ fogs will often cause Botrytis blight, a gray mold, on the buds or flowers. This disease has prevented the production of commercial varieties in coastal areas of California. High relative humidities in early spring encourage the rapid in- crease of rust. Safflower production * - therefore has been restricted to districts having a dry climate, especially in the late summer and early fall. ^ Temperature. The frost resistance of safflower depends upon the variety, stage of development, and plant density. In the seedling stage most varieties will tolerate temperatures down to 20° F, and some experimental types will withstand temperatures down to 10° F. Seedlings spaced 3 to 4 inches apart withstand low temperatures better than those spaced more closely. Once out of the seedling * stage, or once stems have begun to de- velop, safflower becomes more sensitive to frost damage, and temperatures down to 25° F will damage most varieties; In the bud stage or after flowering begins any temperature below 32° F will cause damage. Unless moisture is lacking, safflower apparently does not suffer unduly from high summer temperatures of the Sacra- mento Valley — temperatures that may reach 110° F or higher. Yields generally are highest in years when daytime tem- peratures at flowering time and immedi- ately thereafter are on the moderate side (75° to 90° F). Wind. Safflower has been observed to be quite resistant to damage by wind in the velocity range which characterizes the interior valleys of California. It stands erect and retains the seed in ripe heads during periods when wind velocity near ground level may reach 15 miles per hour. Water The water requirements of safflower have not been precisely determined in Cali- fornia. Practical experience indicates that it will need the equivalent of about 16 to 18 acre-inches of available water for a minimum crop. In California most of this moisture must be stored in the soil, if the crop is grown dry-farmed, since safflower achieves most of its growth after the spring rains stop. Re- quired for economic yields under dry- land conditions is a total of about 25 acre-inches of water, and under irriga- tion, in low rainfall areas, 30 to 44 acre- COMPARATIVE YIELDS OF SAFFLOWER VARIETIES Location Date sown Irrigations N-6 N-10 US-10 Gila Nov. 1949 Irrigated Irrigated pounds per acre El Centro 3,019 2 566 Dec. 27, 1957 2.815 3,436 2,953 Jan. 7, 1959 Irrigated 3.520 3,503 Jan. 11, 1962 Irrigated 3.125 3,240 Jan. 11, 1962 Irrigated 2,856 3,395 Jan. 21, 1963 Irrigated 2,232 2,212 Davis Dec. 22, 1951 Irrigated 2.835 3.290 Dec. 22, 1951 None 2,445 2,085 Apr. 2, 1952 Irrigated 2,175 2,428 Jan. 29, 1953 None 2.602 3,375 Jan. 29, 1953 2 Irrigations 2.475 3,120 Jan. 29, 1953 3 Irrigations 2,565 3,180 Jan. 29, 1953 6 Irrigations 2,572 3,668 Mar. 31, 1953 None 2,092 2,798 Mar. 31, 1953 1 Inigation 1.988 3.188 Mar. 31, 1953 2 Irrigations 2,212 3,150 Mar. 31, 1953 5 Irrigations 2,992 3,178 Mar. 8, 1955 None 1,610 1,254 Mar. 8, 1955 Irrigated 2.133 1.938 Mar. 17, 1960 3 Irrigations 2,966 3,557 3,455 3,725 Mar. 17, 1960 None 3,461 3.324 3,245 Apr. 7, 1961 Irrigated 2,440 2,260 Mar. 31, 1962 Irrigated 4,560 4,540 May 7, 1963 None 2,853 2,627 Kings Co Jan. 22, 1959 None 3,400 3,680 3,350 Jan. 22, 1959 2 Irrigations 2.960 2,870 3,190 Mar. 10, 1959 Irrigated 2,371 2,448 1,901 Note: The first three tests at El Centro were made at the Imperial Valley Field Station, the last three were off-station Imperial Valley field tests conducted by J. P. Jones, W. H. Isom, and Richard Hoover; the tests in Kings County were conducted by Farm Advisor 0. D. McCutcheon; and the test in Tulare County by Farm Advisor W. R. Sallee. [9] inches — including water occurring as rain. Damage from excess moisture. All parts of the plant seem to be very sensitive to excess moisture. Flood irri- gation has led to a high incidence of Phytophthora root rot. Even varieties considered resistant to this disease have been difficult to irrigate successfully in California. During the summer safflower has been killed quickly by standing water or by water-logged soil. As a conse- quence, almost the entire crop is grown dry-farmed, pre-crop irrigated, or on high water table soil or after an irrigated crop. Young plants will withstand tempo- rary water logging if the temperature is in the 60° F range. Soil moisture reserve. In spite of its dislike of excess moisture, safflower prefers a soil well supplied with moisture. Highest yields always have been obtained where subirrigation was carefully con- trolled (see table on page 9) or the soil column preirrigated to wet to a depth of 6 to 12 feet before planting. The low yields of many fields in California ap- pear to be associated with the presence of continuously dry soil at a depth of 3 to 4 feet. Shallow upland soils have not given high yields, and the cause is prob- ably an insufficient reserve of moisture in the subsoil. Under dry-land conditions yields of safflower have been much better on fallowed soil than on continuously cropped land. Soil Safflower is sensitive to the soil environ- ment quite apart from soil moisture. Wherever safflower has been particularly successful it has been on deep, fertile, and well-drained soils of neutral reac- tion. On such soils in California, it has given seed yields about 20 to 25 per cent less than barley. On shallow soils, or soils of low fertility, barley has been relatively more productive. Safflower is similar to barley in its salinity tolerance under dry-land condi- tions, but slightly more sensitive than barley, cotton or sugarbeets when irri- gated. Boron injury has been observed in the variety N-6. In experiments conducted by the USDA Salinity Laboratory at Riverside a salt concentration in the soil saturation extract of 14 to 15 mhos per centimeter reduced yield about 25 per cent. Seven mhos reduced yield 10 to 15 per cent. A concentration of 8.3 mhos decreased ger- mination 10 per cent while 6.8 mhos doubled the time for seedling emergence. A salt concentration of 3 to 4 mhos has- tened crop maturity by about one week. In clay-textured soils in California, stands have sometimes been difficult to obtain. After the winter rains it may not be possible to work such soils until late spring, when cultivation and ensuing dry winds may dry out the seedbed to the depth of tillage. It may be necessary to use seeding equipment with special openers to push aside the dry soil and plant the seed down into moisture. On clay soils, with plantings made during the winter, heavy rains followed by dry winds have occasionally crusted the soil and reduced emergence. Harrowing such fields before emergence has been bene- ficial. The plant does not have any ill effects on the soil. In fact, there is some bene- ficial effect (as measured by improved infiltration rates) from the aggressive root system that penetrates deeply into the soil. Under dry-land conditions, how- ever, safflower will not substitute for a year of fallow, since it usually exhausts the soil of moisture down to depths of 6 to 12 feet. Rotate with other grains. Safflower may be considered a rotation crop for feed grains, wheat and rice, in either a dry-land or irrigated crop-rotation sys- tem. Where rainfall averages less than 17 inches or where weeds are a problem the practice of preceding the safflower year with a year of fallow is advisable. Under dry-farmed conditions, if the annual [10 rainfall is sufficient to wet the soil to a depth of around 4 feet, safflower usually can be inserted as a crop in an annual cropping program. Safflower is fre- quently grown as a dry-land crop on ir- rigable land as a soil-conditioning and weed-control measure. Farmers who op- erate combination livestock-grain setups, value safflower in their rotation system because the crop aftermath provides ex- cellent pasturage for sheep and cattle. Safflower returns have often been superior to spring-planted small grain. This is particularly true in plantings after February 15. In some recent years late planting of cereal crops have been attacked by a virus disease termed "yel- low dwarf." This has reduced the dif- ference in yields between safflower and barley in favor of safflower since saf- flower is not attacked by the disease. The nature of fall weather has had an important bearing on the relative acreage of barley and safflower. With a long dry period after the first fall rains, farmers tend to put most of their available land into barley. Continuous wet weather in the fall and early winter until February greatly stimulates interest in growing safflower. Safflower is well established in the rice- growing district of the Sacramento Val- ley, and particularly in the Sutter Basin. After a rice crop, the land frequently does not dry out enough to be cultivated before the winter rains. When this hap- pens, the land will remain wet until rather late in the spring and too late for small grains to be sown. Safflower, when planted under these conditions, has benefited from the abundant supply of soil moisture in such soils and has not required additional water. Its ability to dry out such soils to considerable depths improves them for succeeding crops. Highest safflower yields on riceland have occurred where the soil is left fal- low for a year after growing rice, and safflower is grown the year before going back to rice. The year of fallow and aera- tion probably permits fuller restoration of chemical and biological activities which characterize typical nonflooded soil conditions required by the safflower plant. Some rice growers have experienced poor safflower seedling growth (except on old levee areas) if they attempted to grow safflower the year immediately fol- lowing rice. Planted in March or April, the seedlings turn yellow and have a leaf tip burn. After a few weeks the field be- gins a recovery and usually produces a crop. However, the yield from a field so affected usually is unsatisfactory. Following a year of safflower growing, one of the small grains or rice would be a better choice than safflower because of the danger of serious damage from saf- flower rust where safflower is grown in two consecutive years. CULTURAL PRACTICES Included here are seedbed preparation, fertilizer application, seed avail- ability and treatment, planting date, seeding methods, and rate of seeding Seedbed preparation Seedbed preparation varies with the dif- ferent areas of the state, with the pre- [in VIOUS crop and soil type. The type of seedbed usually prepared for preir- rigated drilled cereals works well for saf- flower. A well-prepared seedbed for saf- flower has a firm subsoil and a surface mulch free from large clods. Soil mois- ture should begin about 1 inch below the soil surface. In northern California, where safflower is sown in the early spring, it is good practice to fall-plow r and to leave the ground rough during the winter. This conserves rainfall by reducing runoff, and facilitates final seedbed operations. The spring or final cultivations should be geared to destroy successive crops of weeds and volunteer grain. Disking and/or harrowing will usually suffice. It is important to conserve soil moisture in the surface soil while preparing the seed- bed. In the Imperial Valley and the south- ern part of the San Joaquin Valley a preirrigation before planting is usually necessary. This preirrigation should raise the soil to field capacity to a depth of at least 6 feet and preferably to 10 feet. Preplanting cultivation should be similar to that suggested above, although a spring-tooth harrowing may be suffi- cient. Sometimes the seedbed is prepared dry, and the seed broadcast on the sur- face of the soil. Then the ground is fur- rowed out to form beds 36 to 42 inches apart. This operation leaves most of the seed on top of the bed and covered by dry soil. Then preirrigations are given, enough to wet the soil to depths of more than 6 feet. Where safflower is to be surface-irri- gated, raised beds like those used for cot- ton and sugar beets usually have proved best. This type bed reduces root-rot prob- lems. These beds can be prepared in the fall or ahead of the pre-irrigation. In any event, if beds are used their formation becomes a part of the seedbed prepara- tion since they are settled by rain or pre- irrigation before planting. Row crops planted on unsettled beds are difficult to cultivate since, as the beds are wetted down, they tend to settle irregularly and upset the precise row spacing of the original planting. Fertilizer application If the soil is low in nitrogen or phos- phate, drill or work all of the needed chemical fertilizers into the seedbed be- fore planting. The suggested amounts for nitrogen are about 75 to 125 pounds per acre for irrigated safflower, and about 20 to 50 pounds for dry-farmed safflower. Where phosphorus is needed, use 30 to 60 pounds of P L »0 5 (13 to 26 pounds of elemental P) per acre, either as single or treble superphosphate (water soluble P). This may be in combination with nitrogen as a nitrogen-phosphorus fertili- zer. For optimum results, several acre- inches of rainfall or irrigation should follow the fertilizer application. Properly drilled liquid or gaseous fertilizers gen- erally have given the best results for late spring plantings because this places the fertilizer in a zone where soil moisture is more likely to be available to the grow- ing plants. If more than l 1 /^ tons of straw or dry crop residue per acre was returned to the soil by the preceding crop, and safflower immediately follows, apply the larger amounts of the fertilizer range to help decompose the residues and to fertilize the safflower crop. Drill or work the com- mercial nitrogen fertilizer into the seed- bed before planting. Whether it pays to fertilize safflower depends upon • level of fertility in the soil after the last crop • soil moisture relationships • the costs of the fertilization treat- ment versus the price received for the increased yield of safflower. Safflower following a legume, such as alfalfa or a heavily fertilized vegetable crop may not benefit from added ferti- lizer. Dry-land grown safflower even on summer fallowed soil, especially in years of short rainfall, may actually be reduced in yield if the fertilization rate is exces- sive as related to available soil moisture. California county farm advisors have 12] conducted a large number of local saf- flower fertilization tests over the years. Generally these have shown favorable responses to nitrogen fertilizer. On some soil types where cereal crops respond to phosphorus, safflower yields have occa- sionally been economically benefited by NP or phosphorus fertilizer applications. To date, in California, no deficiency of other plant nutrients has been found to limit safflower production. The table be- low shows some results of field trials conducted by county farm advisors. Seed availability and seed treatment Planting seed usually can be obtained from companies contracting with farmers to grow safflower. Most such firms will sell seed of the publicly available varie- ties, with or without a grower contract. To obtain seed of the newest privately developed varieties it may be necessary to enter into a grower contract with the seed supplying firm. Seed as supplied by most California firms will usually be the best available, and will have been tested and labeled for its germination ability. At present only the varieties Gila and US-10 are being certified by the Cali- fornia Crop Improvement Association. To be certified, a variety must be grown in compliance with production rules de- signed to maintain its varietal integrity. The resulting seed must be well screened and graded, bright in color, of good ap- pearance and meet the following stand- SOME SAFFLOWER FERTILIZER RESPONSES Location, soil and year Date application Nitrogen Seed yield Increase Mar. 12, 1963 pounds per acre YoloCo.-Dry land— 1963 1.439 (Rincon clay loam) 25 1.721 282 " 50 1.684 245 " 75 1,598 159 LSD .05 = 82; .01 = 118 Glenn Co.-After rice-1961 Mar. 15, 1961 1,180 (Marvin silty clay loam) " 60 1,522 342 " 80 1,487 307 " 100 1.435 255 " 120 1.585 405 " 140 1.501 321 LSD .05 = 178 Colusa Co.-Rice land-1960 Mar. 15, 1960 60 1,000 1,200 (Hillgate clay loam) 200 '* 90 1,250 250 " 120 1,375 375 " 200 1,550 550 LSD .05 = 208 Colusa Co.-Rice land-1961 50 1.447 1.813 (Sacramento clay) Dec. 1960 366 Mar. 1961 50 2,197 750 Dec. 1960 100 2,060 613 Mar. 1961 100 2,627 1,180 LSD .05 = 249 Note: The tests in Yolo County were conducted by Farm Advisor T. E. Kearney, those in Glenn County by Farm Advisor R. L. Sailsberry, and those in Colusa County by Farm Advisor Karl Ingebretsen. The nitrogen in Yolo and Glenn counties was applied as aqua ammonia just ahead of planting; that in Colusa County, I960, as ammonium sulfate applied just ahead of planting (rainfall after fertilization 2 inches); and that in Colusa County, 1961, as urea (rainfall after spring application 2.9 inches, after fall applica- tion 5.75 inches; all plots planted in March 1961). [13] ards for both registered and certified seed: Laboratory purity 99% (min.) Germination 90% (min.) Inert matter 1% (max.) Seed of other crops 1 seed/lb (max.) Seed of other crops 1 in 2 lb for reg. Weed seed 0.1% (max.) Noxious weed seed .... None (max.) It is important that the seed be treated with a recommended fungicide to con- trol seed-borne rust and Alternaria. These fungi can cause loss of seedling stand and serious foliage diseases in the growing crop. The protecting chemical fungicide seed treatment helps to insure uniform stands of thrifty plants by kill- ing the seed-borne fungi on the surface of the seed, and by protecting the young seedlings from soil organisms. Recom- mended fungicides include volatile mer- cury materials, which should be applied at rates suggested by the manufacturer. Where wireworms or similar soil-in- habiting insects are likely to be a prob- lem, safflower seed may be protected by treating the seed with a recommended in- secticide at rates suggested by the chem- ical manufacturer. Since lindane on occa- sion has adversely affected the germina- tion of stored safflower seed, aldrin is now the preferred chemical, especially if the treated seed is to be stored for more than six months. The insecticide and fungicide may be applied simulta- neously if the manufacturer's recommen- dations so advise. Most seed as now supplied by firms interested in contracting for safflower has been treated before delivery to the farmer for planting. Certified seed may not necessarily be treated to be sold as certified seed. Where a farmer does his own seed-treating he should plainly tag or label such seed: TREATED SEED- SAFFLOWER TESTS ON SEEDING DATES Yields in pounds per acre Year Date sown N-852 N-6 N-10 US-10 Gila 1949-50 Nov. 17— Irrigated Dec. 14— Irrigated Feb. 2 — Irrigated Mar. 16 — Irrigated 3,693* 4,073 3,730 2,845 1958 Apr. 19— Irrigated 4.124 May 31- Irrigated 1,476 1,488 June 24— Irrigated 1,939 1.793 July 17— Irrigated 623 916 1959 Mar. 7 — Irrigated 3,740 3,656 4,110 3,935 Apr. 9— Irrigated 2,705 2,470 2.792 2,962 May 8— Irrigated 1,402 1.357 1,590 1,990 1960 Mar. 18 — Irrigated 4,337f Mar. 18— Nonirrigated 3.8701 Apr. 12— Irrigated 2,551f Apr. 12— Nonirrigated 2,563f 1961 Apr. 18— Irrigated Apr. 18— Nonirrigated 2.6981 2,421f May 26— Irrigated 2,010f May 26— Nonirrigated 2.096f 1961-62 Dec. 21— Nonirrigated Feb. 2— Nonirrigated Mar. 3— Nonirrigated 2,277 2,174 1,697 * Stands thinned by frost, t Average of several spacings. Note: All tests shown were conducted on the Davis campus except those of 1961-62 which were conducted in Orange County by D. M. Yermanos and Farm Advisor Max Cory. [14] POISONOUS— DO NOT USE FOR FOOD, FEED, OR OIL PURPOSES. Treatment should be applied at least 24 hours before seeding. Under dry, cool conditions treated seed cah be stored for several months. Date of planting Date of planting varies according to the location and the season's moisture. For most of the Sacramento and northern San Joaquin valleys, the best planting time is February 15 to March 20, though successful plantings have been made into May and early June (see table, page 14) . In the by-pass or flood areas of the Sacramento Valley, late March and April plantings have given good results, al- though plantings in May and early June, in exceptionally wet years, have yielded from 800 to 2,000 pounds per acre. For best results on Sacramento Valley rice- land, plant before April 20. Plantings in the southern San Joaquin Valley may be made from late Decem- ber through February, and in the Im- perial Valley in January and early Feb- ruary. If they are made earlier than December, the safflower may develop stems too early and become susceptible to damage from frost. Early seedings result in taller plants than later seedings. In areas and years of short moisture on dry land, late March and early April are usually the best planting times. Later spring seedings will result in smaller plants (1% to 2 feet high) better adapted to the available moisture. Summer-planted safflower (after mid- June) has consistently produced low yields in University experiments. Ex- perience has shown that October to mid- January plantings of safflower do not do well in the Sacramento and Northern San Joaquin valleys. Fall plantings have failed because of weed competition (wild oats and others), drowning of seedling plants, and frost and disease damage. Seeding methods Safflower has been grown on the flat or on beds of various width, either solid (broadcast or in close-drill rows) or in wide rows. A pre-irrigation, filling the soil to field capacity to a depth of 6 or more feet, is desirable before plantings, even in areas with more than 20 inches of rain. Generally, drilling has been preferred to broadcasting, particularly in the later part of the planting season. However, for early plantings broadcasting both with ground rigs and from the air has been satisfactory if the seed is covered by har- rowing or shallow disking. Raised beds are desirable where safflower is to be irrigated because this reduces the danger of safflower standing in water and devel- ing root rot. It is important that the safflower seed be placed in moist soil. For this reason late spring plantings, when the surface soil is drying out very rapidly, should be made only with a hoe-opener drill to insure seed placement into moist soil. Preferably the seed should not be planted into the moisture deeper than 2 inches, although the seedlings will emerge from a depth of 4 inches if a surface crust does not develop. If seed is broadcast, harrow to cover to a depth of 2 to 4 inches. The grain drill is most frequently used for both solid and row plantings (by stopping an appropriate number of seed feeds or runs). Drills with single-disk or double-disk-type openers have been satisfactory ; for adobe soils shoe openers are best. For plantings in rows of 12 to 24 inches, most of the conventional-type row planters can be adapted for safflower. For "solid" seedings, rows may be 6 to 12 inches apart. In row plantings the rows should be 18 to 24 inches apart if the crop is grown on dry land. Under irrigation, rows should not be more than 30 inches apart, and highest yield will be obtained if they do not exceed 24 inches in width. [15] Sometimes surface-irrigated safflower is sown on beds on 40-inch centers, with a pair of rows 14 inches apart on each bed. This is the same type of setup that is used for sugar beets; it is used in safflower culture to effectively minimize root-rot problems. SAFFLOWER SEEDING RATES Row spacing Type land 6-12 inches 18-24 inches Drilled pounds per acre Dry land 20-30 25-40 15-20 Irrigated and subirrigated. 20-25 Seeding guide: 18-inch rows @ 20 pounds per acre = 8 seeds per linear foot of row. Seeding rates Seeding rates (table above) will depend on: • Method of culture (dry-farmed or irrigated). Dry-farmed seeding rates are lower, especially if soil moisture is short. • Time of seeding. For late plantings where it is necessary to plant 4 or 5 inches deep to reach moist soil, increase seeding rate by 5 pounds per acre above that shown in the table because some of the seed may fail to come up. • Row spacing. Close drill-row rates are higher than wide-row rates. • Seed size. Some varieties have smaller seed than others and hence have more seeds per pound. • Method of seeding. Broadcast seed- ing requires more seed per acre to com- pensate for loss of seed during the cover- ing operation (harrowing) when some will be buried too deep and some not deep enough and thus will not develop into plants. Use 30 to 50 pounds of seed per acre for broadcast seeding or about 10 pounds per acre more than that shown in the 6— 12-inch column of the table. Safflower seed runs through a drill faster than barley. To seed 30 pounds of safflower per acre, adjust the grain drill to seed 20 pounds of barley or 45 pounds of wheat per acre. . . ,;.v ^^m Effects of plant spacing. The dose sparing above results in tall plants with thin stems and heads close to the top of the plant. [16] YIELDS OF SAFFLOWER FROM DIFFERENT PLANT SPACINGS, DAVIS Date sown Row spacing inches Irri- gation Plant spacings 2" 32" Average Mar. 18 Apr. 12. Apr. 18 May 26. Yes No Yes No Yes No Yes No Yes No Yes No Yes No Yes No 4,376 3.764 2.661 2.649 2.400 2,080 2,560 2,240 2,130 2,230 2,270 2,070 2,370 2,340 1,880 2.030 1960 4,327 3.748 2.641 2,590 1961 2,610 2.330 2.390 2,220 1,950 2,190 1,830 1.980 4,163 3,696 2,461 2,563 2.960 2,740 3,500 2,970 2,830 2.410 2,160 2,310 2,080 2,200 1,940 1,870 pounds per acre 4,482 4,049 3.578 4.273 3.533 3.152 2.442 1.916 1.321 2.450 1,952 1.228 2,900 2.570 1,610 1.870 4,162 3,694 2,240 2,239 2.680 2.410 2.892 2,528 2,450 2,287 2,215 2,190 2,002 2,150 1,883 1,960 What is a satisfactory stand? For close-drill rows, (solid stands) on dry land, three to five plants per square foot are adequate; on irrigated or high-water table land up to five to 10 plants per square foot are desirable. Although saf- flower yields do not vary much over a relatively wide range of seeding rates and row spacings, the plants of thicker stands have thinner stems and are easier Wider spacing results in full, shorter plants with heads distributed over a wider area. [17] to thresh. Stands of less than two plants per square foot usually result in excess weed competition. Under dry-farmed conditions (and in the absence of a high water table) if the stand exceeds six plants per square foot, overcrowding, es- pecially in years of short moisture, may reduce yields. Row-grown safflower (either irrigated or dry-farmed) should average five to 12 plants per linear foot of row in rows 18 to 28 inches apart (table on page 17) . Late-sown safflower will produce smaller plants with fewer heads. Row spacings should be no more than 12 inches to obtain a solid stand of safflower. IRRIGATION Careful irrigation is essential on all but the most permeable and freely draining soils If safflower is to be grown under surface irrigation, two distinctive characteristics must be considered. High susceptibility to root rot, associated with wet soil or standing water, makes careful irrigation essential on all but the most permeable and freely draining soils. On the other hand, deep, vigorous rooting allows saf- flower to tap the reserve of deep subsoil moisture, making it possible to prolong the interval between irrigations. Deep rooting thus can minimize the number of irrigations required during the crop- ping season and reduce the possibility of root-rot injury. Because of these two characteristics, irrigation practice varies Safflower field in the Tulare Lake area of Kings County in 1962. [18] with soil conditions which affect water entry, drainage, water storage, and root development. If the soil is sandy or shallow but drains readily, safflower requires the same irrigation as other crops growing at the same time. Deeper soils with high- water storage capacity permit longer in- tervals between irrigations provided the subsoil is moist in an uninterrupted col- umn. Root rot should not be a problem. If water is very slow to enter the soil or drains very slowly, safflower should not be grown under surface irrigation, because root-rot losses will be severe. Unfortunately most soils which drain slowly also retard root development, and deep preirrigation is not effective. There is a wide range of soil condi- tions between these extremes where sur- face irrigation of safflower can be satis- factory; however, this requires a com- paratively delicate balance between supplying adequate water and avoiding injurious excesses. Following are prac- tices recommended to minimize root rot: • If the deep subsoil is not moist, pre- irrigate to wet to the rooting depth ex- pected by maturity (in deep open soils safflower roots to 10 or 12 feet) . • Plant one of the more root-rot re- sistant varieties. • Furrow irrigate rather than flood. It is best to plant on beds, but furrowing out between flat-planted rows is often satisfactory. If the beds wet quickly and thoroughly, furrow irrigation will be no better than flooding except that furrows facilitate surface drainage. Irrigation in alternate or more widely spaced furrows will minimize water logging. • Irrigate before appearance of drought symptoms. These include wilting and "firing" of the lower leaves. Drought increases susceptibility to root-rot injury. • Do not apply unnecessary irrigations. Check on the soil moisture conditions. • Avoid prolonged irrigation, espe- cially in warm weather. Make sure the surface soil has drained appreciably within 48 hours or less after start of ir- rigation. :d '.::■ ., Subirrigated safflower in the Sutter Basin, 1959. The ditch has been put through the field after planting. Water is maintained in the ditch at 18 to 36 inches below the level of the surface of the soil. [19 • Provide complete surface drainage. Install waste ditches at lower end of the field and make sure furrows are cut into the ditch. The safflower root system is well adapted to the use of water from soil near a water table. Safflower does very well under subirrigation whereas most summer crops would require supplemen- tal moisture supplied by sprinkling or by surface irrigation. The crop is grown mostly on land with natural high-water tables, but is equally adapted to artificial control of the water table or subirriga- tion. WEED CONTROL Methods include cultural and chemical means of controlling a very serious problem The weed problem Accurate figures on the extent of losses due to weeds in safflower are not avail- able. Weeds damage safflower yields in several ways. Early weeds may compete with safflower for moisture, sunlight, and nutrients, thus lowering production and increasing cultivation costs. Heavy in- festations of weeds later in the season may interfere with mechanical harvest- ing, and in extreme cases cause abandon- ment of fields. Since safflower often ma- tures before many common weed species, green weed matter taken in by the har- vester impairs the quality of the product and contributes to spoilage of stored seed. Because adequate surface soil moisture is present initially, and in most cases throughout the season, safflower is often beset by a wide variety of annual grasses and broadleaved weeds. Chief offenders in northern California, where most weed control studies have been conducted, are barnyardgrass or watergrass (Echinoch- loa crusgalli L. ), lambsquarters (Cheno- podium album L. ) , pigweed (Amaran- thus spp.), and other annual grassy and broadleaved species. Perennials such as nutsedge or nutgrass (Cyperus spp. ). Johnsongrass {Sorghum hedepense) and others constitute a separate problem. Cultural control of weeds The most effective weed control is achieved by practicing a sound crop-rota- tion plan which keeps weeds in check. Preferably safflower should not be planted in excessively weedy fields. It is good practice to allow a weed crop to germinate as a result of winter rains be- fore the initial plowing or disking. Spring operations should then be timed to de- stroy one or two crops of germinating weed seeds before planting. The time of seeding safflower also is important in weed control. Early planted safflower grows slowly and is a poor com- petitor with weeds in its early stages of growth. Planted at the optimum time, the vigorously growing safflower restricts weed development and competition. Fall and very early winter seeding, especially in the Sacramento Valley, will prolong the period when safflower grows slowly, and winter weeds may develop ahead of the safflower and smother it. It is better to seed later, after the winter weeds are destroyed and before the summer weeds are well under way. Weed control in most California saf- flower acreage is achieved by well-timed crop cultivations. Row-planted safflower can be cultivated two or three times or as [20] often as necessary until just before flow- ering. It is very important that the last cultivation for row-planted safflower be given as late as possible without causing mechanical damage to the crop. In close- drilled safflower, shallow harrowing or light cultivation has been used effectively to control seedling weeds before the saf- flower emerges, and in young stands when the safflower is 3 to 6 inches high. Such shallow cultivation should be made crosswise or diagonally across the drill rows, and is most successful in a finely worked, trash-free bed. Cultivation from the time of emergence until the safflower is 3 inches high may result in excessive damage to the stand. To minimize crop injury when cross harrowing or light cul- tivating young stands (3 to 6 inches high), select a day with relatively high temperature and bright sun for the oper- ation — plants may be turgid and brittle when they are cold. A rotary hoe, finger weeder or harrow may be used. If you use a harrow, the teeth should be set fairly straight and the harrow "weighted." Since safflower grows rap- idly after it is 6 inches tall, it normally will then compete fairly well with re- maining small weeds. Cross harrowing of furrow-planted and bed-planted safflower is not recommended, as it may damage the stand excessively by burying and otherwise injuring young plants. Chemical weed control Where cultural weed control practices are inadequate, herbicides might be tried to alleviate the weed problems. Chemical weed control practices should be consid- ered as supplements to, rather than re- placements for, cultural practices. Up until 1961 essentially none of the an- nual safflower acreage in California was treated with herbicides. During 1961-62 and 1962-63 the commercial use of pre- plant incorporated EPTC (ethyl N,N-di- rc-propylthiolcarbamate), sold commer- cially as Eptam, increased significantly for control of weeds in safflower. EPTC (and other compounds used in a similar manner) is likely to be more and more accepted as additional growers become familiar with the more economical band application technique, and purchase band, power-driven rotary tiller incor- poration devices for multiple use. Apart from the relatively high cost of herbicide per acre, EPTC has proven generally the most satisfactory of the chemicals tested to date. Many herbicides have been tested for weed control in safflower. Below is a dis- cussion of the more promising of these for possible use under California condi- tions. The summary of test results below does not constitute a recommendation for use of herbicides discussed. For specific current recommendations consult the most recent issue of University of California "Weed Control Recommendations" which is revised annually. It is obtainable from your farm advisor or nearest Agricultural Extension Service Office. Preplant or pre-emergence (with reference to crop) EPTC (Eptam) — Because of its vola- tile nature EPTC must be incorporated into soil immediately after treatment. Satisfactory methods of incorporation in- clude : • Rotary tilling (2-3 inches deep) into level fields • Rotary tilling into the tops of pre- formed beds just ahead of the planters • Disking (4-6 inches deep) and har- rowing with teeth set vertical Although initial expense and mainte- nance costs of equipment may be some- what higher, incorporation of EPTC by a power driven rotary tiller is usually preferred to disking because it is more uniform and better adapted to band treat- ment of the herbicide. When it can be practiced, band application is, of course, more economical than broadcast treat- ment. Because of some uncertainty about 21] <*, Applying EPTC prior to planting as a band on top of the bed, and incorporating it by cultivation. Control of a heavy stand of watergrass and some })igweeds obtained from a band application of EPTC at 3 lbs per acre. The weeds between the rows will be removed ( by cultivation. [22] the actual rate of herbicide per given volume of soil finally obtained, spraying into the beds during listing is considered hazardous with EPTC. The maximum rate registered by the U. S. Department of Agriculture for use in safflower is 3 lbs actual EPTC per s acre. When properly used at this rate on mineral soils, EPTC usually controls most annual grasses and many broadleaved annual weeds. EPTC may be expected to be effective for about 4 to 8 weeks after application under usual conditions. On soils having appreciable organic matter r content (above 15-20 per cent), propor- tionately higher rates would be required for an equivalent degree of weed control. In safflower planted in wide rows (20 inches or more apart) , the per-acre chem- ical cost may be reduced to half, one- third or less by band treatment. A com- mon arrangement in row-seeded safflower is to treat a 10-inch band and use a 9- inch hooded tiller for immediate incor- poration of the chemical. In close-drilled safflower, however, band treatment may be impractical. Others — IPC (isopropyl A^-phenylcar- bamate) and CIPC (isopropyl N-[S- chlorophenyl] carbamate) have proven * promising because safflower has a high tolerance for them. Because of its greater potency, CIPC has been included in sev- ral tests, along with or in preference to IPC. It is an excellent herbicide under appropriate conditions, especially against annual grasses. CIPC is most effective when leached into the soil as a conven- tional pre-emergence herbicide where it acts as a mitotic poison, interfering with weed seed germination. Rain cannot al- ways be expected immediately after planting in the late spring. The results with IPC and CIPC thus have been er- ratic. Soil incorporation of herbicides may increase weed control (by reducing vapor loss) or decrease it (probably by soil di- lution). If safflower is planted into IPC- or CIPC-treated soil, either selectivity or weed control is usually reduced to some extent. In most trials with soil incorpora- tion 2 to 4 inches deep (necessitated by the unpredictability of rainfall), CIPC (4-6 lb/A) has been somewhat less sat- isfactory and never more than equal to EPTC (3-4y 2 lb/A). However, in early (January-March) plantings where shal- lowly incorporated preplant or pre- emergence applications of CIPC were followed by nearly ideal amounts of rain- fall, weed control has been excellent and no crop injury was observed. There is currently no Federal registration for use of CIPC or IPC on safflower. Trifluralin (2,6-dinitro-N,N-di-rc- propyl-a,a,a-trifluoro-p-toluidine) in 1962 and 1963 experimental treatments showed outstanding promise for weed control as a preplant soil-incorporated treatment. Plots treated with a high rate of trifluralin (4 lb/A) were essentially weed-free at harvest and safflower yield was not af- fected. However, trifluralin did cause pronounced early injury (15-25 per cent reduction in stand and vigor). In later studies, trifluralin at 2 lb/A or less has also provided nearly perfect control of most annual weeds with no adverse effect on the crop. For the use of this weed killer in safflower see the current University of California Weed Control Recommenda- tions. Substituted uracils have shown an even greater herbicidal potency than trifluralin on a pound-per-acre basis. However, their margin of selectivity in safflower appears to be quite low. It is not yet known to what extent the ob- served "selectivity" in safflower may be due to the manner and depth of incorpo- ration of the herbicides relative to seed placement. These and several other com- pounds are undergoing further testing. [23 WARNING University of California recommendations for pest control are based on the best information currently available. Treatments based upon these recommen- dations should give control without leaving residues that will exceed the toler- ance established for any particular chemical. To avoid excessive residues, follow directions carefully with respect to dosage levels, number of applications, and minimum interval between application and harvest. Before you treat for control, consult the latest U. C. Pest Control guide. THE GROWER IS LEGALLY RESPONSIBLE for residues on his crops as well as for problems caused by drift from his property to other properties or crops. Postemergence ( with reference to crop ) As yet no herbicide is recommended by the University of California for post- emergence control of annual broadleaved weeds in safflower. However, some ap- pear promising. Barban (4-chloro-2-butynyl N-[3- chlorophenyl] carbamate), sold commer- cially as Carbyne, at 0.38 lb/A as a spray, has shown excellent weed control in safflower infested by wild oats, volun- teer oats or rye, and the crop has ex- hibited a high degree of tolerance to the herbicide. Barban has been developed al- most exclusively as a selective wild oat herbicide. It is highly specific in action against a rather narrow range of species, including oat, wild oat, wild buckwheat and some varieties of rye and ryegrass. Lambast (2,4-bis [3-methoxypropy- lamino] -6-methyl thio-.s-triazine), a po- tent contact herbicide, has been tested experimentally since 1960, with varying degrees of success. When properly ap- plied, Lambast provides excellent control of lambsquarters, and with minimal in- jury to safflower under optimum growing conditions. The optimum stage of growth of saf- flower for treatment is just after the rosette stage but before an extensive can- opy of safflower leaves has developed. Spray volumes of 20 gpa by ground rig or 10 gpa by aircraft have been most sat- isfactory and rates of % lb/A when lambsquarters have 4 to 5 true leaves and up to % lb/A when lambsquarters have 6 to 8 true leaves have been adequate. Other species such as pigweed, chick- weed, knotweed and mustard are con- trolled only when very small (1 to 2 inches tall). Annual grasses, sedges and many other species are not controlled by the suggested rates, and in mixed stands these uncontrolled weeds may flourish after treatment which destroys lambs- quarters and also retards the safflower. Lambast at % to ^4 lb/A commonly causes some chlorosis and depression of safflower height. Vigorous safflower usu- ally recovers completely, or almost so, within 20 or 30 days and develops nor- mal branching and flowering. In extreme cases, i.e., fields heavily infested with lambsquarters (entirely or predomi- nately), the slight herbicidal injury can be tolerated and safflower yields may be increased as much as 100 per cent by treatment. However, the margin of safety with Lambast in safflower is narrow. In fields only sparsely infested with lambsquarters. in fields infested with I 21 troublesome mixed weed species, and in fields of already low yielding potential, treatment with Lambast may not be eco- nomically sound. Suggested, and slightly higher, rates which is never fully recovered, especially if the recovery growth is complicated by other adverse conditions such as cold weather and disease. Where the latter is true, safflower stands may actually be of Lambast may cause severe stunting jeopardized by treatment with Lambast. INSECTS AFFECTING SAFFLOWER Many insect pests attack safflower, but yield is seldom affected Safflower is attacked by many insects discussed in this section of the circular. While they may damage the plants — and particularly the buds — yields are not often affected appreciably. Experiments designed to discover just how much and what types of damage safflower plants can withstand have shown (see table be- low) that the ultimate seed yield was not decreased when even 100 per cent of the buds of the Gila variety were eliminated by de-budding (destroying by mechanical means) at the onset of bloom. Buds removed were less than % inch in diameter, and most of the seed heads left were about to bloom. Remov- ing all of the buds at this period did re- duce the number of good seed heads but the weight of seed per remaining head was very greatly increased. The de- budded plants produced more seeds per head but not larger seeds. The increase in number of seeds was enough to com- pensate for the reduction in number of heads. Spraying for insect control there- fore had no significant effect. Work in progress indicates that most varieties react similarly. Safflower plants appear to have great compensatory powers which explains why the crop yield is not ma- terially reduced by even the most dam- aging insects, such as thrips and lygus bugs, until high-level infestations occur over a long period. COMPARISON OF SEED YIELD WHEN CROP WAS SPRAYED OR DE-BUDDED, DAVIS, 1962 Averages for yield criteria Treatments applied Number of good heads per plant Grams of seeds Weight of 100 seeds (grams) Number of viable seeds in 100 seeds Per plant Per head Check 22 2c 21.0c 18.2 b 21.0c 17.0 b 15.6 ab 13.3a 13.2a 31.8 a 29.4 a 32.2 a 31.0a 31.6a 28.6 a 31.8a 31.0a 1.46 d 1.62 cd 1.58 cd 1.72 be 1.70 be 1.86 b 2.34 a 2.31a 3.85 a 4.04 a 3 85 a 4.09 a 4.20 a 4.12a 4.43 a 4.35 a 97.7 a 98.9 a 25% de-budded 97.9 a 25% de-budded and sprayed twice. 50% de-budded 97.9 a 97.9 a 50% de-budded and sprayed twice. . 100% de-budded 97.9 a 98.0 a 100% de-budded and sprayed twice. 99.1a Note: The chemical used was Dimethoate (4 lb/gal E.C.) sprayed at V 2 lb actual per acre on June 18 and July 2, 1962. Num- bers that do not have a sub-letter in common are significantly different from each other. [ 25 Predaceous spider — one of many species present. Enlarged 2 times. In the light of available information it seems advisable, in order to minimize insect damage, to plant safflower as early in the season as possible for each plant- ing area and particular growing condi- tion. This practice should avoid severe damage from a late season buildup of important insect pests. By that time saf- flower plants will be able to set and ma- ture a full set of buds and seed heads. Under very specific conditions chemi- cal control may be necessary. Consult the Pest Control Guide on Oil Seed Crops published by the University of California Agricultural Extension Service, and your local Farm Advisor. Investigations are v ^ Ladybird beetle larva, Hippodamia spp. Enlarged 4 times. r 26 1 constantly underway to learn more about insect damage, biology, and control. In using insecticides against safflower pests, you must consider not only the pest, its numbers, stage of plant growth, harmful effect on plants, and residues, but also the presence or absence of beneficial predators (see photos on page 26) and the safety to honeybees. Following is a brief description of the various insect pests found on safflower in California. Spring pests On germinating seeds and roots. Wireworms, Limonius spp., occasionally attack plantings made in early or late spring. They reduce the numbers of plants by destroying some of the sprout- ing seeds or by disrupting leader root systems. Such infestations can be con- trolled with pesticides applied as seed treatments. An appropriate fungicide should be combined with the insecticide used for treating safflower seed. Black bean aphids, Aphis fabae Scop. Enlarged 8 times. On seedlings and small plants. The green peach aphid, Myzus persicae (Sul- zer), may become abundant enough in the spring to damage primary buds and seed heads. These primary buds develop a spotty or mottled yellow coloration, and seed production can be reduced by as much as one-third on severely affected plants. Another green appearing aphid some- times called the leaf-curl plum aphid, Aphis helichrysi Kaltenback, has recently caused economic damage to developing buds and seed heads. The symptoms of damage and overall effect to the plant appear to be very much like that pro- duced by the green peach aphid. Air- craft control plots have indicated that several of the new insecticides will con- trol this species as well as the green peach aphid, when used properly after moder- ate to severe infestations occur. Black bean aphids, Aphis fabae Scop., can develop high populations on leaves and terminals of single plants (photo above). Small- to medium-sized groups of plants generally become infested near the margins of fields. This dark-colored species is considerably more damaging than the green peach aphid; as many as [27] n It Adult of western flower thrips, Franklin- iella occidentalis Perg. Enlarged 28 times. 1,200 or more aphids can develop on one plant and severely stunt or completely destroy it. More moderate infestations, about 500 aphids per plant, can still cause appreciable stunting. Light infesta- tions, within a range of 50 to 60 aphids per plant, can be tolerated. Plants se- verely infested by this aphid have lost on the average 50 to 75 per cent of the seed. However, control has usually been unnecessary because only small areas tend to be infested. Insecticides are use- ful when large numbers of plants are moderately to severely infested. Onion thrips, Thrips tabaci Lind.. is an occasional pest of minor or local im- portance. General silvering and bronz- ing of young safflower seedlings occurs when onion thrips emigrate in very great numbers from newly-harvested barley fields nearby. The period of attack is short, and the damage minor. Chemical control has not been necessary. Bud browning and blasting due to western flower thrips feeding. Enlarged 5 times. Midseason pests On developing buds. Recent research has shown that Western flower thrips, Frankliniella occidentallis Perg. (photo above left ) , causes most of the early to midsummer browning, bronzing, and blasting of buds (photo above right) .This occurs on developing buds to a large ex- tent before bloom and before high popu- lations of lygus bugs appear. Some 20 to 25 nymphs per bud of these thrips can cause bud loss. When infestations average 150 nymphs or more per bud the nymphs can destroy all of the buds on a plant. However, field studies have indicated that the plants must lose 38 to 43 per cent of their buds before a loss of seed occurs. Insecticides are not recommended for the control of thrips until 25 to 30 per cent of the early buds are bronzed and blasted prior to the onset of bloom. [28] Adult male lygus bug, Lygus hesperus Knight, on left and nymph on right. Enlarged 5 times. Recently it has been discovered that lygus bugs, Lygus hesperus Knight (photo above), must be present in ap- preciable numbers — 40 per sweep of a standard insect net — to cause significant seed losses. These pests can cause a mod- erate degree of bud browning and blast- ing only when they feed in large numbers on the developing buds prior to bloom- ing. Usually the damaged buds can be distinguished by their sickle shape (photo below) from those injured and blasted by thrips. Most buds fed on by lygus bugs bend over and turn brown, whereas buds browned and blasted by thrips remain upright. Lygus bugs usu- ally cause damage of economic propor- tions (bud loss) only in late-sown fields, after high population densities have had time to develop. Chemical control is not recommended until at least 25 to 30 lygus bugs (including nymphs) per sweep (1 Bud injury, browning and blasting due to lygus bug feeding. Enlarged 5 times. [29] Larva of the looper, Tricho- plusia ni Hbn. Enlarged 2 times. lygus per 8 or 9 buds) are present before the primary buds begin to bloom. On seed heads. Lygus bugs and flower thrips generally remain to feed on seed heads developed from the buds. However, most of this later injury is su- perficial, causes very little loss of seed heads, and only occasionally results in the loss of a few seeds. The heads become too tough for more than localized injury, and the overall dirty appearance of the heads and the prevalence of lygus bugs is misleading. Chemical control is not re- quired after seed heads develop from pri- mary and secondary buds. On foliage. Loopers (photo above) are larvae of a moth Trichoplusia ni Hbn. Occasionally they can become plen- tiful enough to cause considerable loss of leaves, bracts of the larger seed heads, and some seed. However, this type of injury must be defoliating and wide- spread to cause economic damage. Chem- ical control is generally unnecessary. Leafhoppers, Empoasca filamenta De- Long and E. abrupta DeLong, can be- come very plentiful and cause consider- able leaf stippling. Damage is not severe enough to warrant chemical control, since defoliation does not occur and the general plant vitality has not appeared to be appreciably reduced. Leafminers, Liriomyza spp., have been observed to do considerable mining of leaves during midseason. This injury has not been serious, and has merely aided in a faster loss of older basal leaves. This loss is not severe and generally correlated with shortage of water. Control is not necessary. Grasshoppers, including many species of Melanoplus and Schistocerca, feed quite readily on the plants, especially in the foothill areas after small grains are harvested. Damage is usually confined to the margins of fields, but is sometimes [30] m. Sunflower moth larva, Homeosoma electellum Hbn. Enlarged 6 times. Head damage and frass due to larvae feeding of sun- flower moth. Enlarged 3 times. [31] more genera] and severe and appears to reduce the \ ield of oil. Chemical control is possible lmt usually unnecessary. On stems. Larvae of the stem miner, }/<'l(tnogromyza vlrens (Loew), burrow into and tunnel out the stems. The mines cause a wilting of the tips of growing shoots in late spring plantings in the Sacramento Valle\. I rider dry-land con- ditions, this damage was not judged to be serious when found in 1958, but ap- peared to be potentially destructive in late planted irrigated fields. To date, this insect has not become economically im- portant, and control measures have not been developed. Late-season pests Seed heads. These are primarily fed on by flower thrips and lygus bugs, but even less seriously so than earlier in the season. At times the dirty brown or blackened appearance is ominous, but the injury is not very damaging to these maturing seed heads. By late season no additional heads develop so that control measures are not required. The larvae of sunflower moths, Ho- moeosoma electellwm Hulst. (photo page 31 top) occasionally feed on the heads of late-planted safflower (photo page 31 bottom) and destroy the developing seeds. This has been of such minor im- portance that control measures have not been needed. This pest has been observed to infest a high percentage of heads and cause economic damage only in localized areas, when fields were sown late and plants were kept green by irrigation. I nder these special conditions this moth could do serious damage and control measures might become necessary. Stinkbugs, Chlorochroa sayi Stol. and Euschistus conspersus Uhler, can build up to large populations by late summer in the Central Valley. Their mouthparts can penetrate deeply, even into maturing heads. These hugs nun become pests of recognized importance. However, the) have not been studied in regard to crop injury, and the numbers required to d<> serious damage have not been estab- lished. Several available chemicals will control this pest, but none have been tested specifically for this use and none are recommended. Foliage. Grasshoppers, leafminers, and leafhoppers persist in safflower fields until the late part of the growing season. Their damage is generally not serious enough to warrant control measures at this late date. However, in some areas adjacent to rangeland or dry-farmed cereals grasshopper damage can become serious as the insects leave the maturing dry feed for the more succulent green safflower. Red spider mites, Tetranychus urticae (K), and T. pacificus McGregor occa- sionally develop extremely high popula- tions in the Central Valley, especially when midseason temperatures are ex- tremely high and the mites have an early start. As a rule no control measures are necessary, but they are capable of de- foliating a late-sown crop before it ma- tures. The effect of spider mites on saf- flower crops has not been fully studied and no practical control measures have been worked out. Miscellaneous pests Of minor importance on foliage are white flies, woolly bear caterpillars, webworms, and armyworms. Some moth larvae l es- pecially armyworms) on rare occasions migrate into a field in high enough num- bers to cause widespread defoliation. Control measures may he desirable should this happen early in the season. Another minor pest of seed heads has been determined to be a weevil. Several species of small flower beetles have also been identified from safflower plants, but no importance is attached to their presence. I :»2 DISEASES OF SAFFLOWER Crop rotation, irrigation practices, and dis- ease-free seed can be used to reduce loss Several diseases affect safflower in Cali- fornia. Some are widespread and others limited in distribution. The severity of certain diseases, particularly rust and root rot, may vary depending on whether the crop is surface-irrigated, subirri- gated, or nonirrigated. Some diseases are favored by climatic conditions. Crop ro- tation, recommended irrigation prac- tices, and planting treated and disease- free seed are important methods for con- trolling losses from disease. Present com- mercial varieties are not immune to any of the diseases described below. Phytophthora root rot Phytophthora root rot is a serious disease of surface-irrigated safflower. It is very severe following irrigation of fields al- lowed to stress from lack of water prior to irrigation. Root rot may occur in non- irrigated fields when heavy rains occur in the spring. Plants are susceptible at all stages of growth, especially in the seedling stage, but the visible symptoms become more apparent from flowering onward. In- fected plants wilt, become light colored and die. In early stages of infection roots may show a reddening of tissue. Infected roots and lower stem later become darkly discolored. Several races of the causal fungus Phytophthora drechsleri persist in the soil and attack the lower stem and roots under favorable environmental condi- tions. No commercial varieties are immune, but varieties differ in their resistance after the seedling stage. Plant such vari- eties if surface-irrigation is used. Do not allow plants to stress from lack of water before irrigation. (See section on irriga- tion of safflower for cultural practices to control root rot.) Rust Safflower rust is widespread in all areas of commercial production. It is generally more severe on irrigated than on nonirri- gated safflower. Plants are attacked in the seedling and later stages. Infection in the seedling stage results in girdling of the stem slightly below the soil line and frequently in death of the infected plant. Girdled plants wilt from lack of water or are blown down by wind. The foliage infection is characterized by chestnut-brown pustules on cotyledons, leaves, and bracts. The causal agent, Puccinia carthami, has different types of spores. Black telio- spores appear during the summer, and are soil- and seed-borne; Small spores produced by the teliospores infect seed- lings. The wind-borne, chestnut-brown urediospores cause infection of leaves during late spring months when tempera- tures are cool to moderate and humidi- ties relatively high. Aeciospores are known to exist and cause the foliage stage of the disease. Several races of the rust have been identified and indications are that additional ones exist. Commercial varieties resistant to all races are not available although some varieties are resistant to some of the races. The use of rust-free seed and crop rotation are recommended for control. Seed treatment with recommended vola- tile mercury fungicides will give some, but not complete, control of stand loss from seed-borne spores. Crop rotation is effective in reducing stand loss from the soil-borne spores and prevents build up of spores in the soil from successive 33 Fusarium wilt. The plant on the left is disease-free; the center plant shows a characteristic mosaic pattern with half the leaf normal and half dead; and the plant on the right has been almost killed by the disease cropping. In general, late-planted or win- ter- and early spring-flooded fields have less rust infection than early-planted fields. Fusarium wilt A relatively new disease on safflower, Fusarium wilt, is limited mostly to the Yolo bypass and Sutter Buttes produc- tion areas. This disease could become more widespread and serious if it should spread to noninfested areas. Characteristic symptoms are yellowing on one side of the plant beginning on the lower leaves, and wilting (photo above). Older plants may be totally killed or only lateral branches die on the affected side of the plant. Young plants are usually killed. A brown discoloration of the vascular tissue occurs in the stem and roots. The causal fungus is Fusarium oxy- sporum f. carthami. It invades the roots and spreads into the stem, branches, and leaves through the vascular tissue. The fungus persists in the soil, plant debris, and is seed-borne in internal tissue of the hull and the seed coat. Varieties currently grown commer- cially are susceptible. Do not plant seed harvested from diseased fields, since the fungus can be disseminated to disease- free areas in this manner. Rotate saf- flower with other crops in infested areas. I M | ys:t''W ■mi0M "vm ..,:. % 1 m JJJP' f k. % p : # Bacterial blight. The plant on the left is unaffected, the one on the right had it terminal growing point killed, and shows necrotic spots on the leaves. Verticillium wilt This potentially serious disease is wide- spread on safflower in the central part of the state. Plants are attacked at any stage of growth during cool weather but, unless severe, the disease does not rapidly kill the plants. Affected plants generally mature and dry up earlier than normal. A characteristic early symptom is in- terveinal and marginal chlorosis of the lower leaves. The leaves of the entire plant then progressively become mottled in appearance from the lower leaves up- ward. A dark discoloration may be evi- dent in the vascular tissue of infected plants. Verticillium albo-atrum, the causal fungus, is soil- and seed-borne. It is widely distributed in California soils, at- tacking previously grown susceptible crop plants such as cotton, tomato, melons, strawberries, etc. The organ- ism is favored by cool, clay textured soils, high in nitrogen and moisture. The fun- gus invades the roots and spreads into the stem and leaves through the vascular tissue. All current commercial varieties are susceptible. Do not plant seed from dis- eased fields. Rotation is recommended with non-susceptible crops, such as small grains, corn, rice, sorghum, and sugar beets. Botrytis head rot Botrytis head rot or blight of safflower [35 seed heads is a severe disease on safflower in coastal areas subject to continuously high atmospheric moisture. It also is found on safflower in the central part of the state in irrigated fields and fields near irrigation canals where high humid- ity or dew may occur. Infected seed heads become light green followed by complete bleaching. Whether seed is lacking, light in weight, or fully developed depends on the stage of seed development at the time the seed head is infected. The entire infected seed head can be readily detached from its support- ing stem because the bract area tissue is damaged. Spores of the fungus Botrytis cinerea are wind-borne and generally prevalent in the air. Infection of seed heads may occur under favorable environmental conditions at any time from emergence of blossoms to seed-head maturity. Nutri- ent substances produced by blossoms en- hance infection by the fungus. No current commercial variety is re- sistant. Safflower culture presently is not advisable in areas where fog persists be- cause this environmental condition is favorable for severe disease development. Bacterial blight Bacterial blight occurs on safflower if rain prevails during spring months. Rain and heavy dew during winter months en- hance infection of volunteer plants and commercial plantings. It may be found in fields of sprinkler-irrigated safflower. Dark, water-soaked lesions on stems and leaf petioles, reddish-brown necrotic spots with pale margins on leaves and severe necrosis of the terminal bud are symptoms of this disease (photo page 35) . If plants are not killed, they recover under drier weather conditions and de- velop lateral branching. The bacterium, a Pseudomonas syrin- gae, attacks safflower through wounds and natural avenues of entry. Rain spreads the organism in the field, and helps the dis- ease to develop. Varietal resistance to this disease has not been completely determined. Varie- ties Pacific 1, Gila, and I S-10 all have been attacked in commercial fields. Sclerotinia stem rot The above-ground symptoms of this dis- ease resemble those of Phytophthora root rot. Plants turn yellow, wilt, turn brown. and die. Internal stem pith tissue turns brown and the cortical tissue shreds from the fungus rot. A distinguishing characteristic of this disease is black sclerotia in the decayed stem pith near the soil line especially in old, dead plants. Roots are not affected. Stem rot is caused by Sclerotinia sclerotiorum. The fungus persists in the soil and in plant debris in the sclerotial form. Cool, moist conditions are favor- able for infection which occurs on the stem at or near the soil line. Varietal resistance to this disease has not yet been determined. Rotation of saf- flower with nonsusceptible crops is ad- visable. Cucumber mosaic Mosaic caused by cucumber mosaic virus occurs occasionally on safflower. It is common on wild and cultivated plants. The virus is spread from infected plants by winged, green-peach aphids, Myzus persicae. Infection of safflower appar- ently occurs early in the growing season and symptoms appear on older plants. A light- and dark-green mosaic pattern is typical of the virus (photo page 37) . Leaf distortion and plant stunting may occur. Affected plants develop to maturity. All commercial varieties are suscep- tible. To date the disease has not been serious in California. Alternaria leaf spot Although leaf spot caused by Alternaria cart ha mi is not a general problem on saf- flower in California, it can be found in coastal and other areas where fog or | 36 during the summer heavy dew occurs months. Characteristic large, brown spots de- velop on leaves. Seed may be discolored. The fungus causes seed rot and damping- off of seedlings. Present commercial varieties are not resistant. Frost injury Frost during winter and spring months may cause considerable damage to saf- flower. Cracking of the stem and blister- ing of the epidermis on leaves are evi- dent on frosted plants. Secondary organ- isms may invade cracked stems and cause rotting of the pith and damage to inter- nal tissue of the upper root. Affected plants die at a later stage of growth. Boron injury Boron injury may occur on safflower in some areas of the lower Sacramento Val- ley, particularly where boron toxicity occurs on other crops. Leaf margins turn brown, and the affected areas enlarge until the entire leaf is killed. Where boron injury is a limiting factor, the use of low boron irrigation water, if available, is recommended. A i# % s. ' £'