M . : 
 
 f Agricultural 
 
 f r\ c r a i i c r\ d m i a 
 
 I |*i it If 
 
 f 
 
 H. Z. HIELD 
 
 R. M. BURNS 
 
 C. W. COGGINS, JR. 
 
 PRE HARVEST USE OF 
 
 ON CITRUS 
 
 !» 
 
(h n Hi LLU is the popular name for 2,4-dichlorophenoxyacetic acid, a 
 plant growth regulator of proved value to the citrus industry. When properly 
 used, 2,4-D can reduce pre-harvest fruit drop, increase fruit size, reduce leaf 
 and fruit drop following pesticide oil sprays, and lessen fruit stem die-back. 
 
 This circular tells how to use 2,4-D on citrus. 
 
 MAY, 1964 
 
 The Authors: Henry Z. Hield is Specialist in the Citrus Research Center and Agricultural Experi- 
 ment Station, Riverside; Robert M. Burns is Extension Horticulture Technologist, Riverside; Charles 
 W. Coggins, Jr., is Assistant Plant Physiologist in the Citrus Research Center and Agricultural 
 Experiment Station, Riverside. 
 
PRE HARVEST USE 
 
 OF 
 
 ON CITRUS 
 
 H.Z.HIELD • R.M.BURNS • C. W. COGGINS, JR. 
 
 Dlant growth regulators such as 2,4-D 
 cause a change in normal plant proc- 
 esses when used in small amounts. In cit- 
 rus spraying, the type of 2,4-D used is of 
 vital importance as there are many types 
 marketed for weed killing and some of 
 them will cause damage to citrus at con- 
 centrations used for growth regulator 
 purposes. The only form of 2,4-D which 
 should be applied to citrus in California is 
 the high-volatile ester, which is labeled as 
 a citrus growth regulator. 
 
 CONTROLLING 
 FRUIT DROP 
 WITH 2,4-D 
 
 When used as recommended on nearly- 
 mature to mature fruit, sprays of 2,4-D 
 may be expected to reduce drop about 50 
 per cent. These "drop-spray" treatments 
 become effective approximately 1 week 
 after application. Regulator sprays reduce 
 the drop of some unsound as well as sound 
 fruit, and this leads to high cullage in the 
 packing house if a large percentage of un- 
 desirable fruit is present in the orchard. 
 
 The maximum period of effectiveness 
 of a drop spray is 3 or 4 months. Sprays 
 applied while fruit has a partially green 
 rind may delay development of color for 
 about 10 days and therefore 2,4-D should 
 
 not be applied to early market orchards. 
 The principal difference in effectiveness of 
 an 8 ppm (parts per million) and 16 ppm 
 concentration of 2,4-D in the spray is the 
 greater period of time over which drop is 
 controlled by the higher concentration. 
 2,4-D reduces fruit drop mainly because 
 of the effect on the fruit stem; the treated 
 fruit stems remain alive and functional 
 longer because there is delayed develop- 
 ment in the abscission zone (the separa- 
 tion point of fruit and stem). 
 
 2,4-D sprays should never be applied to 
 citrus fruit less than 7 days before harvest. 
 
 Navel Oranges 
 
 It is estimated that approximately two- 
 thirds of the navel orange orchards in 
 southern California are treated with 2,4-D 
 to reduce fruit drop. Here, the most desir- 
 able treatments are either a 16 ppm water 
 spray in October or November, or an 8 
 ppm water spray in December or January. 
 In groves where summer oil spray is ap- 
 plied for insect control the inclusion of 4 
 ppm of 2,4-D will often give partial con- 
 trol of preharvest fruit drop. 
 
 In the central San Joaquin Valley, where 
 whitewash sprays are applied in October 
 to repel leafhoppers, the inclusion of 24 
 ppm of 2,4-D will give good mature-fruit 
 drop reductions. Where 2,4-D is not in- 
 cluded in the whitewash, a water 2,4-D 
 spray may be applied at 16 ppm in Octo- 
 ber or November, or at 8 ppm in Decern- 
 
ber, provided it is applied at least 2 days 
 prior to, or 2 to 3 weeks following, white- 
 washing. 
 
 Valencia Oranges 
 
 Pre-harvest fruit drop reductions may 
 be obtained with 2,4-D spray concentra- 
 tions so low that they will exert no influ- 
 ences on the following year's fruit size. An 
 8 ppm spray applied when fruit is an aver- 
 age of at least Vi -inch in diameter will re- 
 duce mature-fruit drop but will not cause 
 a fruit-size increase on the next year's 
 crop. A reduction in mature-fruit drop, 
 and an increase in fruit size of the follow- 
 ing crop, may be affected in one spray by 
 following the fruit-sizing procedure de- 
 scribed on page 5. 
 
 Valencia oranges are generally less sub- 
 ject to severe fruit drop when held late on 
 the tree than are navel oranges and grape- 
 fruit. 
 
 Grapefruit 
 
 Reduction of fruit drop in grapefruit 
 requires dosage and timing similar to that 
 necessary for Valencia oranges. A spray 
 of 16 ppm applied in June or July will 
 reduce fruit drop during summer and early 
 fall. The young fruit should average at 
 least % -inch in diameter in order for final 
 size to be unaffected. If fruit-sizing sprays 
 are applied before June or July drop of 
 mature fruit is reduced, but not as much 
 as by drop sprays applied later in the 
 season. 
 
 In the central San Joaquin Valley a seri- 
 ous winter fruit drop may occur, and a 
 spray of 24 ppm of 2,4-D in an October 
 whitewash, or a water spray of 1 6 ppm in 
 October or November, should be used. 
 
 Lemons 
 
 In inland areas of southern California, 
 4 ppm of 2,4-D in the fall oil-spray appli- 
 cation reduces fruit drop in the early 
 spring. 2,4-D sprays are also often desir- 
 able because they cause a delay in the 
 development of the yellow rind color of 
 
 the fruit. A water spray of from 8 to 12 
 ppm applied during November to De- 
 cember will have approximately the same 
 effect on the fruit as 4 ppm of 2,4-D in oil. 
 
 FRUIT-SIZING 
 SPRAYS 
 
 Spray formulations of 2,4-D applied to 
 small green fruit are called "sizing sprays." 
 When 2,4-D-treated fruit reach maturity 
 they usually show an average increase of 
 approximately one commercial size class. 
 In oranges this is usually associated with 
 an increase in the thickness and roughness 
 of the rind. This may result in a reduction 
 of from 1 to 2 per cent less fruit in first- 
 grade commercial quality, but for growers 
 having a small-size problem the increase 
 in size more than compensates for the 
 slight decrease in quality. (Juice weight is 
 lowered about 1 per cent, but soluble sol- 
 ids and acid contents are not influenced.) 
 
 The normal rind texture and size of 
 fruit produced by an orchard should be 
 considered before applying a fruit-sizing 
 spray: if the fruit is rougher than average 
 for the district, 2,4-D sprays should not 
 be applied; if the orchard has a history of 
 
 Table 1. 2,4-D Concentration for 
 Fruit-Sizing Sprays* 
 
 Average fruit diameter 
 
 Concentration of 
 2,4 D in spray 
 
 inches 
 
 Grapefruit: 
 1/4 to 3/8 
 
 ppm 
 12 
 
 3/8 to 5/8 
 
 16 
 
 5/8 to 3/4 
 
 20 
 
 3/4 to 1 
 
 24 
 
 Oranges: 
 3/16 to 1/4 
 
 12 
 
 1/4 to 1/2 . 
 
 16 
 
 1/2 to 5/8 
 
 20 
 
 5/8 to 3/4 
 
 24 
 
 
 
 * Average fruit diameter in the orchard determines the 
 appropriate concentration to apply. 
 

 
 
 \ , / / "><** 
 
 % / 
 
 
 w 
 
 
 i , % #' 
 
 % 4 
 
 111 
 
 AVERAGE SIZE 
 
 Figure 1. Young grapefruit. Note average-sized fruit used to determine fruit-sizing spray concentration. 
 
 satisfactory-to-good rind texture, but has 
 poor sizes, a sizing spray should be con- 
 sidered. (2,4-D sprays cause a greater de- 
 gree of rind roughness in light-crop years 
 than they do in normal or heavy-crop 
 years.) 
 
 The proper concentration of 2,4-D is 
 determined by the average diameter of the 
 young fruit (table 1 and figure 1), and a 
 random measurement throughout the or- 
 chard must be made to determine average 
 fruit size. Sprays applied too early during 
 the bloom period may cause excessive 
 fruit thinning, while sprays applied as 
 much as 3 months after bloom will be 
 relatively ineffective in increasing fruit 
 size. 
 
 i 
 
 Valencia and Navel Oranges 
 
 A spray may be applied at any one of 
 the concentrations shown in table 1 with 
 approximately equal effectiveness. Sprays 
 stronger than the 24 ppm concentration 
 are not recommended, not only from a 
 residue standpoint but also because greater 
 concentrations may result in leaf curl in 
 subsequent growth. The responsiveness of 
 the young fruit decreases rapidly with size 
 increase. Fruit size is not as general a 
 problem with the navel as it is with the 
 Valencia orange. 
 
 Grapefruit 
 
 The general specifications for sizing 
 sprays on oranges are applicable to grape- 
 
t * m 
 
 12 
 
 16 
 
 20 
 
 24 
 
 ppm 
 
 WI '1 ' i 'lii i Ji i iiii'i' iii i i yi iiiiiii i i i i i i j, 
 
 Figure 2. Young navel and Valencia oranges, and appropriate 2,4- D concentrations for a fruit-sizing spray. 
 
 fruit, although size-concentration catego- 
 ries are different because of the larger 
 fruit. Quality of grapefruit is less affected 
 by growth regulator sprays than is quality 
 of any other common citrus variety, and 
 the response of grapefruit to 2,4-D sprays 
 is not as great as with oranges. 
 
 Lemons 
 
 Because response of lemons to fruit- 
 sizing experiments has been variable, 
 2,4-D sprays are not recommended. 
 
 ADDITIONAL 
 EFFECTS 
 OF 2,4-D 
 
 Splitting at the navel end of Washington 
 navel oranges may cause a considerable 
 loss of fruit. Fruit-sizing sprays have 
 sometimes resulted in approximately a 50 
 per cent reduction in splitting. Current in- 
 
 formation indicates that 2,4-D has no 
 effect on creasing or puffing of navel or 
 Valencia oranges, and puffing and creas- 
 ing of rinds associated with over-maturity 
 is not delayed by the sprays. 
 
 Delay of granulation has been observed 
 in Valencia oranges which were sprayed 
 to increase fruit size, but after the initial 
 delay no further effects of the sprays were 
 evident. 
 
 Fruit stem die-back occurring late in the 
 harvest season is reduced by 2,4-D fruit- 
 holding sprays; this results in more turgid 
 fruit and more fruit at harvest. 
 
 Pesticide oil sprays occasionally cause 
 leaf and fruit drop. This drop may be re- 
 duced by the inclusion of 2,4-D in the 
 spray oil at a concentration of 4 ppm. 
 
 2,4-D has not increased fruit-set on any 
 citrus variety in California. 
 
 2,4-D is a potent weed killer and should 
 be handled with care to avoid plant dam- 
 age. This material is of a low level of 
 toxicity to humans, but should never be 
 sprayed over fruit less than 7 days before 
 
harvest. The Federal Residue Tolerance 
 for 2,4-D in ctirus is 5 ppm (based on 
 fruit weight). 2,4-D has been registered 
 by the USDA for citrus when used as 
 directed. 
 
 In growth regulator usage, concentra- 
 tions are approximately one one-hun- 
 dredth of those used in weed killing. The 
 concentrations used on citrus will cause 
 severe damage to some plants, such as 
 cotton, grapes, olives, or tomatoes, and so 
 the effect on adjoining acreage must be 
 carefully considered when planning a 
 spray application. 
 
 Leaf Injury 
 
 2,4-D sprays should be timed to avoid 
 periods of immature leaf growth, as they 
 will cause leaf curl and distortion of young 
 growth even at recommended concentra- 
 
 tions. Applications after a growth flush 
 has matured and hardened, or before 
 start of new growth, will minimize or 
 eliminate leaf distortion. 
 
 Tree Damage 
 
 Using 2,4-D in forms other than the 
 high-volatile ester, or making large errors 
 in calculating proper concentration, has 
 caused severe tree injury. On mature trees, 
 injury has ranged from severe leaf curl 
 and chlorosis to a reduction in the amount 
 of growth during one or two succeeding 
 growth cycles (although these trees later 
 resumed normal growth). 
 
 Trees less than 6 years old should not be 
 sprayed with 2,4-D. The unfavorable ef- 
 fects on fruit quality and tree growth re- 
 sulting from a spray application to young 
 trees more than offsets any possible bene- 
 fits in fruit size or reduction in fruit drop. 
 
 Figure 3 (left). Pinched tips and slight cupping of grapefruit leaves 2 to 3 weeks after 2,4-D spraying. 
 
 Figure 4 (right). Mature grapefruit leaves showing slight buckle resulting from a 2,4-D spray applied when leaves 
 were in a half-expanded and soft state of growth. Similar results occur when spray is applied during a growth flush. 
 
HANDLING 
 2,4-D 
 
 2,4-D should not be sprayed from air- 
 craft. The hazard of low volume, high 
 concentration sprays, and the danger of 
 drift to adjoining crops, has resulted in 
 regulations generally prohibiting such 
 application. 
 
 Once the desired concentration for a 
 ground-spray has been determined it is 
 necessary to determine the strength of the 
 commercial product to be used. The 
 pounds per gallon of acid equivalent is 
 given on the label; this value is used to 
 determine the actual volume to be added 
 to each tank of spray mixture for a given 
 concentration. Table 2 gives data on 500- 
 gallon quantities of spray mixture. 
 
 The 2,4-D formulation should be pre- 
 measured into small containers, as this 
 precludes possible errors in measuring 
 during the spray operation and eliminates 
 spillage in the field. Small, wide-mouthed 
 bottles are satisfactory, and can be rapidly 
 filled from a large burette or from a 
 graduated cylinder; the amount of 2,4-D 
 required for a tank of a given volume at 
 the desired concentration is placed in one 
 bottle. Containers should be emptied and 
 rinsed directly into the spray tank — a wire 
 basket over the tank-opening eliminates 
 danger of bottles dropping into the tank. 
 
 Before spraying, the spray hose should 
 
 be directed on the ground until liquid 
 which has been standing in the hoses is 
 flushed out. Spray mixtures should not 
 stand in equipment, as contamination or 
 precipitation may occur. 
 
 The small quantities of lime used to 
 neutralize zinc sulfate sprays have not in- 
 fluenced the effectiveness of 2,4-D added 
 to this type of nutritional spray; urea 
 added to citrus 2,4-D sprays has not in- 
 fluenced their effectiveness. 
 
 Additional emulsifiers or wetting agents 
 are not necessary in the sprays discussed in 
 this circular. 
 
 Weather 
 
 Regulator sprays are most effective 
 when applied during warm sunny weather. 
 Absorption of the regulator by leaves is 
 rapid; rainfall 48 hours following appli- 
 cation has not lessened effectiveness. 
 
 Tree Condition 
 
 Adequate soil moisture and healthy 
 trees will help assure effectiveness of the 
 spray (trees needing water may not 
 respond). 
 
 Gallonage 
 
 Necessary coverage depends upon the 
 purpose of the spray; fruit-sizing applica- 
 tions require more complete wetting of the 
 tree than do sprays designed for mature 
 fruit-drop reduction. Tree size, the 
 presence of other materials in the spray 
 
 WARNING ON PESTICIDE RESIDUES 
 
 These recommendations for chemicals are based on the best information cur- 
 rently available. Treatments based upon these recommendations should not leave 
 residues that will exceed the tolerance 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. 
 
 The grower is legally responsible for residues on his crops as well as for prob- 
 lems caused by drift from his property to other properties or crops. 
 
(such as pesticides and nutrients), and the 
 type of spraying equipment used, all in- 
 fluence the gallonage required. Commer- 
 cial spray operators can give accurate 
 estimates of the gallonage required, but in 
 general applications of not less than 500 
 gallons per acre for fruit sizing and not 
 less than 350 gallons per acre for reducing 
 fruit drop are recommended. Reducing 
 gallonage and increasing the 2,4-D con- 
 centration is not advisable, as damage can 
 result from an uneven distribution of spray 
 applied at concentrations higher than 
 recommended. 
 
 Compatibility of 2,4-D 
 With Other Chemicals 
 
 2,4-D materials are often combined 
 with pesticide and nutritional sprays to 
 eliminate the need for several spray opera- 
 tions. 2,4-D is compatible with the pesti- 
 cide and nutritional materials in common 
 use. (Consult your local Farm Advisor for 
 current spray recommendations if there is 
 a question as to compatibility.) 
 
 Oil Sprays 
 
 The ester forms of 2,4-D more readily 
 enter the plant when in an oil solution. 
 Fruit-sizing and fruit-drop spray concen- 
 trations given here are for water-spray 
 mixtures only; therefore, drop or sizing 
 sprays should not be combined with pesti- 
 cide oil sprays. Oil sprays occasionally 
 cause leaf and fruit drop due to oil injury 
 to the plant; this may be reduced by the 
 inclusion of 2,4-D in the spray at concen- 
 trations not exceeding 4 ppm. 
 
 Recommended amounts of oil-type wet- 
 ting agents required by other materials in 
 a spray mixture have not undesirably in- 
 fluenced the 2,4-D plant response. 
 
 Whitewash Sprays 
 
 Whitewash sprays used on citrus in the 
 Central Valley may contain as much as 15 
 pounds of lime per 100 gallons of spray. 
 This quantity of lime reduces the effec- 
 tiveness of a particular concentration of 
 
 2,4-D. Increased 2,4-D concentrations 
 needed to compensate for 2,4-D made in- 
 effective by lime are given on pages 3 
 and 4. 
 
 Cleaning Spray Equipment 
 
 Equipment used for spraying 2,4-D 
 should never be used for spraying 2,4-D- 
 sensitive crops; 2 ,4-D -contaminated weed 
 spray equipment should never be used for 
 tree sprays. 
 
 2,4-D sprays should be drained from 
 equipment and hoses when the operation 
 is completed. Residues may be reduced by 
 rinsing with water, refilling with water to 
 stand overnight in the tank, pump and 
 hoses, and then flushing again with clean 
 water. This precaution should be sufficient 
 to safeguard citrus against leaf curl in 
 future spray operations. 
 
 DOSAGE 
 RECOMMENDATIONS 
 
 Use a high-volatile ester formulation, 
 the label of which specifies that it is pre- 
 pared for use on citrus. Spray only once 
 and never less than 7 days before harvest. 
 All sprays should be water mixtures unless 
 otherwise specified. 
 
 Control of Fruit Drop 
 
 Navel Oranges — Southern California 
 
 (1) 16 ppm in November or December, or 
 
 (2)8 ppm in January, or 
 
 (3)4 ppm in summer oil spray. This spray may 
 
 not give good fruit-drop reductions late in 
 
 the season. 
 Navel Oranges — Central California 
 Do not spray early-maturity orchards. 
 
 ( 1 ) 24 ppm in October whitewash spray, or 
 
 (2) 16 ppm in October or November, or 
 (3)8 ppm in December. 
 
 Valencia Oranges — Southern California 
 
 (1)8 ppm when young fruit of following year's 
 
 crop is at least Vi-inch in diameter, or 
 (2) A combination fruit-drop fruit-sizing spray 
 
 following the fruit-sizing procedure. 
 Valencia Oranges — Central California 
 Here, Valencias are usually picked relatively 
 early in the season and drop is seldom a problem. 
 
Grapefruit — Winter Fruit Drop — 
 Central California 
 
 (1 ) 24 ppm in October Whitewash spray, or 
 
 (2) 16 ppm in October or November. 
 Grapefruit — Summer Fruit Drop — Southern 
 and Central California 
 
 (1) 16 ppm when young fruit of the next year's 
 crop is at least 3 /4-inch in diameter, or 
 
 (2) In a combination fruit-drop and sizing spray 
 following the fruit-sizing procedure. 
 
 Lemons — Southern California (inland) 
 (1)4 ppm in a summer or fall oil spray, or 
 (2) 8 ppm in November or December. 
 
 Fruit-Sizing Sprays 
 Oranges and Grapefruit — Southern California 
 Spray only once, using water-spray mixtures only. 
 Do not use 2,4-D sprays if orchard usually pro- 
 duces rough fruit, or if an early harvest is 
 planned. See tables 1 and 2 for further data. 
 
 PREPARATION 
 OF 2,4-D SPRAYS 
 
 The amount of 2,4-D needed in a spray 
 is based on the pounds per gallon of 2,4-D 
 
 acid equivalent contained in the commer- 
 cial preparation. This acid equivalent is 
 stated on the label of the container. 
 
 To find ppm concentration of 2,4-D for 
 volumes other than 500 gallons, use the 
 following formula: 
 
 Parts per million x gallons in hundreds x 
 factor (see table 2) = amount of 2,4-D in 
 ml (milliliters). 
 
 Example 7. To get 12 ppm in 400 gallons 
 of spray mixture when using a 4 pounds 
 per gallon material. Use 1 ppm per 100 
 gallon value 0.79. Multiply 12 ppm x 4 
 (gallons in hundreds) x 0.79 = 38 ml( 37.9 
 rounded) of 2,4-D. 
 
 Example 2. To get 4 ppm in 600 gallons of 
 spray mixture when using a 3.44 pounds 
 per gallon material. Use 1 ppm per 100 
 gallon value 0.95. Multiply 4 ppmx6 
 (gallons in hundreds) x 0.95 = 23 ml (22.8 
 rounded) of 2,4-D. 
 
 Table 2. Common Acid-equivalent Values of 2,4-D and Amounts of 2,4-D in Milliliters Used 
 to Obtain Various Parts Per Million Concentration of 2,4-D in 500 Gallons of Spray 
 
 
 Concentrations of 2,4-D 
 
 Factor in milli- 
 liters for 1 part 
 
 Acid equivalent 
 
 4 ppm 
 
 8 ppm 
 
 16 ppm 
 
 20 ppm 
 
 24 ppm 
 
 per million per 
 100 gallons 
 
 4 pounds per gallon 
 
 3.34 pounds per gallon 
 
 3 pounds per gallon 
 
 2 pounds per gallon 
 
 1 pound per gallon 
 
 15.8 ml 
 
 18.9 
 
 21.1 
 
 31.6 
 
 63.1 
 
 31.6 ml 
 37.8 
 42.1 
 63.2 
 126.3 
 
 63.2 ml 
 
 75.6 
 
 84.2 
 126.3 
 252.6 
 
 79.0 ml 
 
 94.6 
 105.3 
 157.9 
 315.8 
 
 94.7 ml 
 113.5 
 126.3 
 189.5 
 379.0 
 
 0.7896 
 
 0.9456 
 
 1.0528 
 
 1.579 
 
 3.1586 
 
 10 
 
HOW THE UNIVERSITY OF CALIFORNIA 
 WORKS WITH AGRICULTURE 
 
 As one of the nation's Land-Grant institutions, the University of California 
 plays a multiple role in service to agriculture. This involves teaching, re- 
 search, and conveying the facts developed by research to those who may 
 put them to good use in the best interest of all the people. 
 
 These activities are combined in the University's Division of Agricultural 
 Sciences. This statewide framework includes: 
 
 The College of Agriculture providing instruction in agriculture and re- 
 lated sciences on campuses at Berkeley, Davis, Los Angeles, and Riverside. 
 The Schools of Forestry and Veterinary Medicine function as separate pro- 
 fessional schools within the Division but are closely related to the College of 
 Agriculture. 
 
 The Agricultural Experiment Station conducting research on the four 
 campuses mentioned above as well as on numerous field stations, experi- 
 mental areas, and farms throughout the state. Closely allied with the Ex- 
 periment Station are the Gianni ni Foundation of Agricultural Economics 
 and the Kearny Foundation of Soil Science. 
 
 The Agricultural Extension Service with 53 offices serving 56 counties 
 carrying out the responsibility of "extending" research results to the people. 
 The service cooperates with the Experiment Station in local research on 
 thousands of farms. It also conducts youth educational activities through 
 the 4-H Club program. 
 
 Co-operative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture 
 cooperating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. George B. Alcorn, Director, California Agricultural Extension Service. 
 
 15m-5,'64(E4120)V.L. 
 
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 3 
 
 *-#-* 
 
 BLACK 
 BOXES... 
 
 Agriculture has them too 
 
 Both manned and unmanned vehicles sent into space are 
 equipped with "black boxes" that record or transmit in- 
 formation needed by space scientists who hope to explore 
 other planets. 
 
 Not as glamorous perhaps, but equally important to our 
 country's welfare are the measuring devices used by agri- 
 cultural scientists to gain knowledge that will improve 
 conditions on our own planet. From information in such 
 "black boxes" will come better farming methods, better 
 foods and fibers, better living. 
 
 The agricultural sciences offer rewarding careers for 
 qualified young men and women who would have a part 
 in making the future better. Write for the booklet AGRI- 
 CULTURE-OPEN DOOR TO YOUR FUTURE. 
 
 -w* 
 
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 vj) 
 
 Agricultural Publications 
 
 University Hall 
 
 University of California 
 
 Berkeley 4, Calif. 
 
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