CALIFORNIA AGRICULTURAL EXPERIMENT STATION THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA • BERKELEY A Strawberry Breeding Program, with its goal the development of varieties especially suited to California growing conditions, has been un- der way at the University of California for a number of years. FIVE NEW VARIETIES were introduced in 1945. These varieties— SHASTA, SIERRA, LASSEN, TA- HOE, and DONNER — were described and made avail- able for trial as fresh market berries, but their adapta- tion to all parts of California was not then adequately determined. /fot& tZUZtCttH' is intended to do two things: 1 — make a report on the horticultural value of the five varieties introduced in 1945, in the light of four more years of trial in numerous growing areas; 2 — introduce two new selections, CAMPBELL and CUPERTINO, which have shown promise in experimental plots and in a number of small com- mercial plantings, but the extent of whose adapta- tion is not yet known. *76e ;4ut6o>i4, Richard E. Baker is Assistant Professor of Pomology and Assistant Pomol- ogist in the Experiment Station, Davis. Victor Voth is Senior Laboratory Technician in the Experiment Station, Davis. REPORT OF THE AGRICULTURAL EXPERIMENT STATION OF THE UNIVERSITY OF CALIFORNIA From July 1, 1949, to June 30, 1950 CONTAINING Agricultural Experiment Station Bulletins 71 4-71 6 Agricultural Experiment Station Circulars 392-396 and 340, 347 (Revised) Agricultural Extension Service Circulars 155-167 and 15, 50, 73, 137 , 138, 146 (Revised) NOTE: No Director's Report was issued for this period. UNIVERSITY OF CALIFORNIA, BERKELEY, CALIFORNIA 1950 LIBRARY 1WVERS1TY OF CALIFORNIA BREEDING AND TESTING RICHARD E. BAKER and VICTOR VOTH Since the introduction of the five so- called University varieties of strawberries in 1945, further tests of the selections, as well as of some 1,100 seedlings, have been made. An isolation nursery has furnished virus-free plants for trial in test plots throughout the state. As a result of this continuing testing program, the characteristics, adaptation, and horticultural value of the varieties have become better known. In addition, the tests have indicated that two new se- lections are worthy of introduction at this time. Conditions of the Tests Isolation Nursery. All of the selec- tions have been maintained in separate plots in an isolation nursery near Win- ters. None of the plants in this nursery is known to be infected with virus dis- eases. The location is isolated from com- mercial and home-garden plantings of strawberries. The normal spread of virus diseases of the strawberry is known to be relatively slow in the Winters district. Only varieties, selections, and new seed- lings developed at the University are maintained there. Commercial varieties and selections from outside sources are not planted in or near the isolation nurs- ery. This nursery is maintained as a source of virus-free strawberry plants for trial in the various test plots throughout the state. Fruit Records. Plants of all selections have been taken from the isolation nurs- ery and planted in small trial plots in the central coast area, in the interior valley, and in southern California. Notes have been taken several times throughout each season on the characteristics of the fresh fruit. Records of production, size, and appearance have been accumulated for each picking for each selection through- out each season from 1946 through 1948. The same type of record has been kept for all selections in replicated plots and in commercial trials. Preliminary storage tests have been used for the more promising selections with fruit samples stored at 40° F for 10 days. Notes have been taken on each sample before and after storage. This pro- cedure indicates in a preliminary way the shipping quality. Preliminary tests also have been used to determine the value of selections for freezing. This work has been done in cooperation with the Divi- sion of Food Technology. Plant Records. The resistance of the more promising selections to verticillium wilt has been tested in a disease nursery at San Jose. Selections have been inocu- lated with this disease and planted in in- fested soil. Standard varieties of known commercial resistance have been included in the test for comparison with the selec- tions which were being studied. The re- sistance of the selections to strawberry yellows, powdery mildew, salinity, and red-spider damage has also been re- corded. A summary of plant and fruit characteristics is given on pages 8 and 9; pictures of the fruit on pages 10 and 1 1; and pedigrees for the University varieties on pages 15 and 16. 3] EVALUATION OF VARIETIES INTRODUCED IN 1945 In response to many requests for re- cent information on the Shasta, Lassen, Sierra, Tahoe, and Donner varieties, an evaluation based on commercial trials is given here. These varieties have almost completely replaced the Banner variety in the central and north coast region where they are adapted. They have been planted extensively in the interior valley and in southern California where their adaptation was not definitely known. Many plantings are located in moder- ately saline soils. The Lassen and Donner varieties have fair resistance to salinity. The Sierra, Tahoe, and Shasta varieties are less resistant. In coastal locations some growers are attempting to leach neutral salts out of the surface soil by using sprinkler irrigation at all times of the year except during the picking season. Because sprinkler irrigation during the picking season may cause too much fruit rot, a special type of double-row bed with a high central ridge is used to avoid salt 7% V-v*" 4 accumulation near the plants. The irriga- tion water is distributed in furrows be- tween the beds, and the plants are located on the sides of the bed and close to the furrows. The salts which accumulate in the surface soil as a result of this type of irrigation are concentrated mostly in the high ridge between the rows of plants; thus the plants may escape injury from the salt accumulation. This type of bed has been used for strawberry culture in the Imperial Valley, but it has not been used extensively for commercial plant- ings in other locations. In semi-coastal and interior locations, it is possible that the sprinkler system may not cause too much fruit rot during the picking season so that it could be used throughout the year. In any case the irrigation water must not contain high concentrations of sodium or chlo- rides. Water of this kind would increase the salinity problem regardless of the method of application. |3lr m % \f: u * "mm * m>. ~% * hi, / -f? * i Fig. 2. Lassen has large, smooth, glossy leaves cupping slightly upward. Sfauta In the central and north coast areas Shasta is the most popular variety. The total seasonal yield is greater than that of all other varieties except Lassen. Pro- duction is fairly continuous throughout the season with peaks less pronounced than for other varieties. This variety is susceptible to injury from verticillium wilt and moderate sa- linity. It ranks above Donner and Lassen but below Tahoe and Sierra in resistance to verticillium wilt. It is more susceptible to injury from moderate salinity than any of the five varieties. In the Sacra- mento and northern San Joaquin valleys the Shasta variety has not produced satis- factorily. Crops have been light and the production season is short. In southern California it is short-lived in all locations where it has been observed because it is not tolerant to moderate salinity. Shasta has fair resistance to the hot-water-dip treatment used for the control of cycla- men mite. Fig. 1 (Left). Round leaves of the Shasta variety are bluish green and cup downward. ^, ' > C> ," y J*y - ic S& > k' -J./ y j... F v>?j . ** k t ^ -'.-*v ^•' '' xV •'•'M v. ,*r> Sfcr # ;/:: i?P •'),> *S a»£ «* [6] of a normal crop. Apparently the winter rains leach enough of the toxic salts out of the surface soil so that the plants can recover for a few months. St &&M&1 The Donner variety is third in popu- larity in the central and north coast re- gion. Its season of production is similar to Lassen but the total yield is less. Don- ner is probably more susceptible to strawberry yellows than any of the five varieties. For this reason many plantings in the central and north coast region are short-lived. It is only slightly more re- sistant to verticillium wilt than the Lassen variety and ranks next to the latter in its tolerance to modern salinity. In the interior and southern California its performance is approximately the same as that of Lassen, even in regard to production. Since strawberry yellows is not a major problem in the interior, Donner may be as long-lived as Lassen in that region. In coastal regions of south- ern California, where strawberry yellows is a major problem, the Donner variety may be short-lived because of this disease. Fig. 3. Top, Donner variety has smooth, light green leaves; center, leaves of Sierra are wrinkled and dull gray-green; bottom, Tahoe plants have medium sized, dark leaves which cup upward. cewta The Sierra variety is fourth in popu- larity in the central and north coast re- gion. The total production is less than that for Donner. Both the spring and fall crops are relatively light. The fruit is rather rough, the seeds protrude from the flesh, and the tip is often green or whit- ish in color instead of red. In verticillium resistance, however, this variety sur- passes all others. It ranks with the Ban- ner variety in its resistance to this disease. In salinity tolerance Sierra ranks be- low Lassen and Donner but above Shasta. In the interior valley, production has been poor, and fruit characteristics have been unsatisfactory as mentioned above. In southern California the Sierra variety has made weak growth and produced only light crops on moderately saline soils. In soils which are relatively free of sodium and chlorides the Sierra variety will pro- duce light crops of large, attractive fruit the first season following winter planting. 7&6oc The Tahoe variety is the least desirable of the five varieties in the central and north coast region. Production is too light; the fruit is small, soft, and poorly colored. Tahoe ranks next to Sierra in resistance to verticillium wilt, but it prob- ably does not have enough resistance for commercial plantings in most soils in- fested with this disease. In salinity tolerance the Tahoe variety ranks about the same as Sierra; in other words it is not very tolerant. In the in- terior it will produce more than Shasta or Sierra, but less than Lassen and Don- ner. A few berries will mature during the summer and fall months but not enough for a commerical picking. In southern California its growth response is about the same as Sierra but production is less. [7] PCtutttutd 'ptutt (ZfanacterUtticA of strawberry Adaptation Periods of poor production Begins bearing Nubbins Total production Skin texture Flesh texture Flesh color Hollow Juiciness Flavor Quality fresh Value as shipper Use of fruit Lassen Sierra Central and north coast; central valley Central and north coast; Sierra foothills early summer; early fall first % summer end of April first week May summer, many summer, many very good fair to good Tahoe Central and north coast first % summer first week May summer, many fair to good Vigor good fair to good good Runner production very good good excellent Leaf type large; smooth; glossy wrinkled; large; dull green medium size; smooth Flower stem type medium long; high branching long and high branching medium long; high branching Longevity of plant good good fair Virus resistance good fair fair Verticillium wilt resistance poor excellent fair to good Mildew resistance fair fair poor Red-spider resistance excellent poor fair Salinity resistance fair poor to fair poor to fair Fruit color light red; glossy medium red; glossy; white tip light red; glossy Fruit shape round conic to blunt conic conic or wedge long conic Fruit size large primaries large medium Seed color and position yellow; flush with surface of fruit yellow to red; flush to raised yellow or red; flush Aroma slight slight slight tender medium tender medium tender soft medium firm medium firm light red red light red small small luicy moderate moderate subacid subacid subacid fai r or poor fair fai fair to good fair to good fair to good fresh market fresh market fresh market Quality frozen Resistance to hot-water dip poor to fair fair to good fair excellent poor; too soft fair to good VARIETIES INTRODUCED BY THE UNIVERSITY OF CALIFORNIA Shasta Central and north coast; S. San Joaquin first Vi summer last week April few good fair good bluish green; cupped down Donner Campbell Central and north coast; central valley Central and north coast first V2 summer; fall late summer- late fall last week April last of April few few fair to good good good good good very good similar to Lassen medium size; smooth Cupertino Central and north coast late summer; early fall early May few good good good medium size; smooth medium long short medium long medium long fair fair good good fair poor good fair poor poor poor poor fair poor poor fair fair fair poor fair poor fair fair fair medium red; glossy bright red; glossy medium red medium to dark red round conic to blunt conic long conic conic to wedge conic medium medium to large medium to large large greenish yellow; flush yellow; flush yellow; flush yellow; flush none slight slight highly aromatic medium tender medium tender medium tender medium tender medium firm medium firm medium firm medium firm medium red red bright red red to whitish small small to medium small large moderate juicy moderate moderate mild subacid subacid subacid subacid fair good fair good fair to good fair to good fair to good fair to good fresh market fresh marked- home garden fresh market fresh market fair fair no commercial trials no commercial trials fair to good fair to good fair fair ^ffe'p'iuiU (fattfrcvtect [10] Fig. 4 (Opposite). Top to bottom: Shasta, medium red and glossy, round conic to blunt conic in shape, greenish yellow seeds; Tahoe, long conic berry, light red in color; Sierra, medium red with white tip, conic or wedge shaped, yellowish seeds sometimes raised; Lassen, round or blunt fruit, light red in color. Fig. 5 (Above). Donner, a bright red, glossy fruit with long conic shape. Fig. 6 (Below). The new introductions: Campbell, a medium red, conic to wedge- shaped fruit; Cupertino, dark red, conic berry, and highly aromatic. Hi] NEW INTRODUCTIONS The two new strawberry varieties de- scribed below are being introduced for trial in the central and north coast re- gions as fresh market berries. Their per- formance in trial plantings in southern California and in the interior valleys in- dicates that they are probably not adapted there. Both have shown merit in several locations in the central and north coast region. Since neither has been sufficiently tested to determine the extent or limits of its adaptation, no final recommenda- tions for use can be given here, nor is it assumed that both varieties will have en- during value. These varieties are the sixth and sev- enth to be introduced as a result of the breeding program. They represent what appear to be two of the more promising progeny of crosses made in 1935 and 1939 by H. E. Thomas and E. V. Gold- smith. Their release at this time has been brought about by numerous requests from commercial strawberry growers in the central coast region who are thor- oughly satisfied with their performance in small commercial plantings. They have been selected by them for expanded plant- ings even though some of the fruit and plant characters are not ideal. Both varieties have specific character- istics which are not possessed by any other strawberry variety grown in Cali- fornia. They have already been used by commercial growers as desirable addi- tions to plantings of the 1945 University introductions. Botanically the two new varieties have perfect flowers. Neither, however, has been grown entirely alone and away from other strawberries; therefore both have always had opportunity for cross-pollina- tion. The characteristics of strawberry plants and fruit vary from season to sea- son and from year to year. The descrip- tions which follow will therefore not be accurate in every detail for all fruits in all seasons or years. (ZamfifaM The variety Campbell has shown prom- ise in all test plantings made in the central coast area during the seasons of 1946 and 1947. It has been used successfully by commercial growers in the Santa Clara Valley during the seasons of 1946 to 1948. It was included in trial plantings at El Monte and Oxnard from 1946 to 1948 where it was moderately vigorous and tolerant to salinity, but the produc- tion was unsatisfactory. In the interior valleys it was tested during the 1947 and 1948 seasons. The production period lasted only three weeks and the total yield was less than that for Donner and Lassen. Campbell has been tested under the Uni- versity number of California 467.1. It is the result of a cross made in 1935 and was selected in 1937. Characterization The plants of Campbell are similar to Tahoe in many respects. They are not ex- ceptionally large. The leaves are similar to those of Tahoe but they are cupped upward less than those of Tahoe. The plants are moderately long-lived if they are given good care. This variety will yield an abundance of runners. One mother plant will produce as many as 125 runner plants. The berries are borne on strong, up- right, moderately high-branching stems. They are conic, symmetrical, and medium red in color. The flesh is medium firm, juicy, bright red. The finish is bright and the size is medium to medium large. The seeds are approximately flush with the surface of the fruit and yellow in color. The dessert quality is equal to that of Tahoe, Shasta, or Sierra. [12] Campbell starts production as early as any of the 1945 University varieties in the central coast region. It bears through- out the season from late April or early May until late fall. The crop is somewhat heavier during spring, early summer, and early fall but production is continuous between peaks. Its early summer peak follows the spring peaks of the other Uni- versity varieties while its early fall peak precedes the fall peak of the others. The inclusion of Campbell in a planting with other University varieties would there- fore spread the heavy production season over a longer period of time. Campbell is only slightly more resist- ant to verticillium wilt than is Lassen. It is rather highly resistant to yellows but susceptible to mildew and to injury from red-spider. It is fairly resistant to injury from the hot-water-dip treatment used for the control of cyclamen mite. Description of the Fruit Size, medium to large; shape, conic, with good symmetry; color, bright red with good gloss ; seeds, yellow, flush with the surface of the berry, and medium in size and spacing; skin, moderately tender; flesh, moderately firm and juicy, bright red; slight hollow; aroma, very little; dessert quality, fair; shipping quality, good; total production, good with peaks in spring, early summer, and early fall in the central coast region. @ufientiH* This variety has shown promise in small commercial plantings in the Santa Clara and Pajaro valleys during the pro- duction seasons of 1946 to 1948. It was tested in trial plantings at El Monte and Oxnard during the seasons of 1946 to 1948. It was moderately susceptible to salinity. The vigor was less than for Campbell. The production was unsatis- factory. In the interior valleys it has been tested at Davis and Florin during the sea- sons of 1946 to 1948. It begins production a few days later than other University varieties and continues for only three weeks. The total crop is too light and the Fig. 7. Campbell has smooth leaves cupping upward and with brilliant luster. >\ se i*" Fig. 8. Cupertino has dark green, somewhat pointed leaves. season is too short. During unusually cool seasons in the interior valleys, there may be some summer and fall production. Cupertino has been tested under the University number California 829.9. It is the result of a cross made in 1939 and was selected in 1941. Characterization The plants of Cupertino are moderately vigorous, dark green, and unlike any of the other University varieties in appear- ance. The plants are long-lived when planted in the proper site and under good cultural conditions. It will not yield as many runner plants as Campbell. One mother plant will produce approximately 90 runner plants. The berries are borne on low to mod- erately high-branching stems. They are conic, symmetrical and medium to dark red in color. The flesh is medium firm, juicy, and light red to whitish in color. The finish is exceptionally bright, the size is large, and the aroma is pleasing; these three characteristics are the out- standing features of the fruit. The seeds are flush with the surface of the berry and yellow in color. The dessert quality is good when not overripe. The flavor is poor and the color becomes dark as the berry approaches maturity. Berries of this variety must be picked at the proper stage of maturity for best color and flavor. Cupertino starts production several days later than other University varieties in the central coast region. It bears throughout the season from early May to October. The crop is somewhat heavier during late spring, early summer and late fall. Its peaks of production do not coin- cide with those of other varieties. Its in- clusion in a planting of other University varieties would therefore help to spread the heavy production season over a longer period of time. This variety is less resistant to verticil- lium wilt than the Lassen variety. It is moderately resistant to yellows, mildew, and red-spider. It is fairly resistant to injury from the hot-water-dip treatment used for the control of cyclamen mite. Description of the Fruit Size, large; shape, conic, with good symmetry; color, medium to dark red with exceptional gloss; seeds, yellow, flush with the surface of the berry, and medium in size and spacing; skin, mod- erately tender ; flesh, moderately firm and juicy, light red to whitish; large hollow; highly aromatic; dessert quality, good at proper stage of maturity; shipping qual- ity, good; total production, good with peaks in late spring, early summer, and late fall in the central coast region. 14] 'PedfyieeA of university varieties SHASTA = Cal. 403.8 Cal.67.5 Cal. 177.21 Nich Ohmer U.S.D.A. 634 U.S.D.A. 543 Cal. 68.24- -U.S.D.A. 634 N. Y. 4626 LASSEN = Cal. 544.2 Cal. 21.9 Cal. 161.1 DONNER Cal. 579.4 Cal. 145.52 Cal. 222 CaK BH 14 (mixed crosses) Redheart U.S.D.A. 634 Banner Blakemore Nich Ohmer Cal. 66.2 Cal. 7.20« SIERRA = Cal. 537.5 Nich Ohmer Cal. 177.21 U.S.D.A. 543 Cal. 68.24 U.S.D.A. 634 N. Y. 4626 TAHOE Cal. 567.6 Cal. 144.21 Cal. 143.32 Narcissa Nich Ohmer Narcissa Cal. BH 14 (mixed crosses) [15] 'Pedfaneet of new introductions Cal. 177.21 CAMPBELL -Cal. 467.1! k Cal. 103.22 U.S.D.A. 543 Cal. 68.24 Cat. A08 Nich Ohmer U.S.D.A. 634 N. Y. 4626 U.S.D.A. 253 F, U.S.D.A. 253 Cal. 611.4 Cal. A08 (U.S.D.A. 253 x F 2 U.S.D.A. 253) ,Cal. 168.3 y Cal. 103.22' / \