LIBRARY STATE PLANT BOARD .TA' 3-543 U.S. DER^RTMENT OF AGRICULTURE BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE June 1941 niRTHSB EESULTS PROM AIEPLAiTS DUSTINS I!T 121 ZOM FOE I£SJ.1IPTE.H0"JS COTTON INSF.Cr CONTIiCL, CiiO? SEASON 0]? 1940 By T. P. Cassidy and T. C. Ear"ber, Division of Cotton Insect Investi>:mtionsi' Introduction Inv3stiga,tions on control of heaipterous cotton insects in Arizona "by ths use of insecticides applied with airplanes vere con- tinued during the crop season of 1940 for frrther testing of control . methods on a practical coa^mercial "basis. In 1938 and 1940 circulars?.' were issued l)y the Bureau of Entomology end Plant ^^larantine listing the species of henipterous insects responsitle for reducing cotton yields and lowering grades of Arizona cotton. These circulars described the nature of daaage to cotton, the extent of damage in the State, and the losses caused oy hsmipterous insects directly and indi- rectly, and gave the progress of experimental v;ork done on tnis group of insects through 1959. The results of the experiinents of 1940 are given at the present time because of the great interest in the v;ork and the dem.and for information "by the grov^ers for the coining season. Pield experiments conducted during 1933 to 1938 v/ith several insecticides applied v/ith hand and pov/er-operated dusting machinery indicated that profitable gains in yield could be made by the use of insecoicides and the quality of cotton improved. However, these methods of application v/ere not entirely satisfactory for large-scale commercial dusting luider Ari^^ona- conditions owing to irrigation schedules, the rank grov/th of cotton plants, sudden insect migrations to cotton fields requiring iranediate poison applications, etc. T"ie use of airplanes appeared to be the most satisfa.ctory method for quickly dusting large acreages following insect migration into the fields without damaging rank growing cotton. l/ The writers were assisted in the field by V/. A. Stevenson, L. W. Sheets, J. M. Breazeale, and H. J. Crawford. 2/ Cassid;/, T. P., and Barber, T. C. Hemipterous Cotton Insects of Arizona and Their Economic Importance and Control. U. S. Dept. Agr., Bur. Ent. and Plant Q,iaa,r. Circ. E-439 (mimeographed). Cassidy, T, P., and Barber, T. C. Investigations in Control of Hemipterous Cotton Insects in Arizona, by the Use of Insecticides. U. 8. Dept. Agr., Bur. Snt. and Plant Q,uar. Circ. S-506 (mimeographed). -2- In 1939 a series of large-scale dusting experiments was conducted cooperatively with the J. G, Boswell Company and a number of cotton growers to o"btain information on the efficiency', practica.'bility , and cost involved in this method of insect control, and to determine the minimum numter of injurious hemipterous cotton insects that would justify the expense of airplane dusting. In 1940 a similar series of airplane dusting experiments was conducted in cooperation with the J. G. Boswell Company, the Cortaro Farms Company, and a nximter of cotton growers. The same insecticide (paris green 7 1/2 percent, dusting sulfur 92 1/2 percent) was used "both years, the sa^e dosage of 15 pounds of insecticide per acre per application was used, and the same time interval of 7 days "between dustings was followed as closely as possihle. The main difference "between the experiments of 1939 and 1940 was in the num"ber of insecticide applications made per field. In 1939 a rigid schedule of applications was followed after dusting had commenced and each field in the Salt Eiver "Galley received seven applications of insecticide irrespective of whether the insect population was light or heavy. This gave valuable information as to the minimum nvim"ber of injurious hemipterous insects required to justify the expense of control. However, several of the experiments of 1939 failed to show profitable results because of the excessive number of applications. Cotton-Dusting Experiments by Airplane in 1940 In the experiments of 1940, 4 representative fields of short- staiple Acala cotton and 3 fields of long-staple SxP cotton in the Salt Eiver Valley and one field of long-staple cotton in the Santa Cruz Valley were dusted. Each field contained 40 or 80 acres and was laid out in alternate dusted and check plots of 10 or 20 acres so that half of each field was dusted and the other half left vmdusted for comparative purposes. The number of applications used depended upon the abundance of the insects. Population counts v/ere commenced June 17 by using the sweep-net method of collecting. When fields were found to have an average population of 12 or more mirids ( Lygus , etc.) or other injurious hemipterous insects per 100 net strokes, or 6 or more stinkbugs v/ere found by examining 100 plants, it was assumed that sufficient insects were present to justify the expense of airplane dusting for their control, and dusting was begun. However, when populations in the dusted areas of the fields dropped below this number the dusting was stopped until the insects again reached the above populations. Ey following this procedure the number of dustings made in the different experimental fields varied from two to seven. The insecticide used was a commercial mixtiire of 7 1/2 percent paris green and 92 l/2 percent dusting sulfur applied at the rate of 15 pounds per acre at 7-day intervals. The first application was made on July 10 and the last on August 22. Dusting conditions during 1940 were almost perfect for airplane dusting and practically every application was made under excellent weather conditions. In 1939 conditions were very different, and it was necessary to change the dusting schedule on several occasions because of high winds and unfavorable weather. The favorable conditions prevailing during 1940 are considered an important factor in the BUCceBBful results that wore obtained in the experiments. --3- Aftor the cotton from the dxisted and check areas was picked and weighed it was ptit into separate trailers and followed through the gins so that the percentage of lint, the grade, and the staple length of all cotton produced could "be determined. By comparison of these records the value of the cotton from the dusted and nondusted areas of each e:i:perimental field was determined and the profits from the dusting were calculated. Results of the 1940 Experiments Rendition of lint (gin turn-out), grades, and staple. — Oin records from three fields of short-staple and three fields of long-staple cotton located in the Salt River Valley shov/ that the dusted cotton yielded 0.14 percent more lint than did the xondusted. The classing and grading records of the lint from all the experimental fields are shov/n in tahle 1. Tahle 1.- Classing and grading records of cotton from experimental fields, 1940 Dusted Check No of bales Percent No. of bales Perceni Short staple — Acala Total yield 85 65 — Grade- Strict Middling 27 31.4 17 26.2 Middling 49 57.0 42 64.6 Strict Low Middling 10 11.6 6 9.2 Color- White 81 94.2 52 80.0 Spotted 5 5.8 13 20.0 Staple — 7/8" 0.0 3 4.6 15/16" 13 15.1 13 20.0 1" 45 53.5 34 52.3 1-1/32" 27 31.4 15 23.1 Long- staple— SxP Total yield 39 33 — Grade- No. 1 4 10.3 0.0 No. 2 16 41.0 15 45.5 No. 3 18 46.2 14 42.4 No. 4 1 2.6 4 12.1 Staple — 1-1/2" 38 97.4 30 90.9 1-7/16" 1 2.6 3 9.1 Owing to excessive rainfall during the picking season, cotton grades were adversely affected generally throughout the State. Nevertheless, the above records show that the dusted cotton averaged somewhat better in grade and staple than the "undusted cotton from the check plots. UBRARY Increased V^lue of Cotton from Dusting As shown in the classing and grading records, a "better quality of cotton was produced in the dusted than in the nondusted areas. In order to determine the value of the better quality of cotton in dollars and cents, each tale of short-staple cotton from the dusted and check areas was valued according to the G-overniiient loan value, f.o.t. ware- house, Phoenix, Ariz., for the different grades and staples. The long- staple cotton was valued according to average conunercial prices paid for different grades in Arizona. The increased value of the cotton from three fields of short-staple and three fields of long-staple located in the Salt River Valley, computed on a 500-pound hale "basis, varied con- sidera"bly in the different locations, depending upon the intensity of insect populations. The increased value of the short-staple varied from 20 cents to $1.66 per "bale and that of the long-staple varied from $2.85 to $30.05 per "bale for the different fields. Yield and Cost Data In determining the profit or less from comparable areas of the experimental fields all the costs for insecticides and dusting by air- planes as well as those for picking, weighing, nauling, ginning, bagging, and ties for the increase in yields in the dusted fields were charged at the prevailing rates. In computing the costs per acre the exact acre- ages of the dusted and check areas v^ere determined. All irrigation ditches, roads, fence rows, and other idle areas were eliminated from the acreage. The measured net acreage of an 80-acre block of short-staple cotton, which v/as divided into two fields (4A and 4E) by an irrigation ditch and a ro9.d and surrounded on fo\ir sides by a fence, was 72.8 acres, of which 37 were dusted and 35.8 acres were left undusted for checks. The detailed records of the cost of dusting and the value of the crop produced in the dusted and check areas of these fields are shown in table 2, as an example of hov/ the costs and profits were calculated. Table 2. — Yields and cost data of dusting experiment Field 4A and 4B Total seed cotton produced, dusted areas Total seed cotton produced, check areas Difference gained Difference gained Total lint cotton produced, dusted areas Total lint cotton produced, check areas Difference gained Difference gained Average price per pound, Average price per pound, Difference due to grade. dusted cotton check cotton color, and stapl( 73,550 lbs. 49,160 lbs. 24,390 lbs. 49.61 percent 26,299 lbs. 17.333 lbs. 8.956 lbs. 51.71 percent 9.33 cents 9 .00 cents .33 on Tatle 2. (cont.) Busted 26,299 lbs. lint at $9.33 Check 17,333 lbs. lint at $9.00 Difference gained Difference gained Total seed produced in dusted cotton Total seed produced in check cotton Difference gained Difference gained Dusted seed sold for Check seed sold for Difference gained Difference gained Gross profit from lint cotton G-ross profit from seed Gross profit $2,453.30 1.559.57 693.73 57.31 percent 45.004 lbs. 30,351 lbs. 14,653 lbs. 48.28 percent $ 430.05 289.32 140.73 48.64 percent $ 893.73 140.73 1,034.46 Co I 3t records of cotton gained: Dusting at $1.14 per acre per application (7 applications) $319.20 Picking 24,390 lbs. seed cotton gained at 75^ per 100 lbs. 182.92 Weighing and hauling 24,390 lbs. seed cotton at 10.;z^ per 100 24.39 Ginning 24,390 lbs. seed cotton gained at 30,'^ per 100 73.17 Bagging and ties for 8,966 lbs. lint cotton gained at ^1.25 per 500- lb. bale 22.41 Total cost 622.09 Gross profit Total cost Ket profit Ket profit per acre ^1: ,034.46 622.09 412.37 11.15 The yields, costs, and profits from the three fields of short- staple and the three fields of long-staple cotton grown in the Salt River Valley and from one field of long-staple in the Santa Cruz Valley that were dusted for hemipterous insect control have been computed on a per- acre basis and summarized in table 3. It will be seen from this table that the number of dust appli- cations rajiged from four to seven, or an average of six in the short- staple fields. Five applications were made in all the long- staple fields in the Salt River Valley, and only two applications in the field in the Santa Cruz Valley. The pounds of seed cotton gained per acre as a re- sult of the dusting in the short-staple fields varied from 267 to 817 pounds, or an average of 569 pounds per acre. For the four long-staple fields there were variations in gains of 201 to 317 pounds, or an aver- age of 268 pounds per acre. After all expenses involved and the value of the cotton gained were determined it was found that the short-staple -6- fields gave a net profit varying from $3.73 to $14.30, or an average of $9.00 per acre. The profits for the long-staple fields varied from $6.78 to $13.24, or an average of $9.41 per acre for the four fields. All fields com'bined gave an average net profit of c?9.23 per acre. m o N •H O +» o o o o o cd a> -p o I o -P Pi'H - o CO «H 0) -H O f^ (h ^» 0) O ft P. nJ o 'd e^ o s (H •H nd o S) 0) (1) 0) _ CO fciiD M 0) • H -H -P •H n5 rt I ■p -p O O fi o « ■p I »H <9 OS 0) o ,g t3 -H o O P< -P )j at M fl , O o ^ ^ rH bO cr\ OJ J- CM CT^ 00 CO ^ OJ ^ 8 ^ ^ ^ OJ OJ R, r — CTi CO bO rH CVl cr. CO ON c\j r^ ^ rH CM rH CO f — O CO rH o rH rH ^cS 00 rH lA rH ITS C\J ^; rH ^ c\j r-i C\j r-i C\j CO CO CJ^ rH CO r-1 8 J- rH CO rH CO CO O o LP* 00 C\j r-i cO VX) c:> LPi Lr> ir\ t^ ir\ ur\ LTi C\J -=!■* 8 rH o rH CO 8} rH o ^ rH X) ^ rH t>^ cr> j::f r^ cr\ t — rH CO o a> C\J J- LO CVJ u^ LP> LO CA 0) cr> 1^ ^_ CM cr. C\i CO LO CO 6 rH r-l rH r-i CO O O t^ uo Jd- r- (M cu H O CO rH ru (M rH J=i > . rt pj > © i-O to f^O rt a u CO d. f-P rH -=1- ^ < > > > 6 w rt rt CO oa CO CO "i!^ -8- iliii An 80-acre field of short- staple cotton grown in the Salt River Valley near !.!esa during; 1940 was dusted foiir times during the season for hemipterous insect control "but was not included in the above summary. The season's records on insect populations, "boll injury, form counts, etc. indicated that a profit from the dusting operations would "be made in this field. However, owing to adverse weather conditions during the picking season and a shortage of labor, the cotton was not picked. It was allowed to stand in the field iintil January 1941, when it v/as finally snapped. While the dusted portion of the field produced 306 pounds or 20.6 percent more snapped cotton per acre than did the undusted, the field showed a loss from the dusting. The lint cotton from the field sold for 6.5 cents per pound irrespective of grade and color, and after all expenses for dusting, picking, weighing, hauling, bagging, ties, and ginning were deducted the increased yield made from the dusting showed a net loss of 17 cents per acre. This experiment indicates that no profit can be made from dusting cotton if it is not picked and handled in a normal way. Summary and Recommendations The series of airplane-dusting experiments conducted during the season of 1940 show that a reasonable profit can be made from dusting long- and short-staple varieties of cotton with a mixture of 7 l/2 percent paris green and 92 1/2 percent dusting sulfur for the control of hemipterous insects. The dust should be applied at the rate of 15 pounds per acre at 7-day intervals when 12 or more mirids ( Lygus , etc.) or other in- jurious hemipterous insects can be collected per 100 sweep-net strokes, or when 6 or more stinkbugs can be found by examining 100 plants. When the insect populations drop belov; these numbers the poison appli- cations should be discontinued until populations again reach 12 or more per 100 sweep-net strokes or 6 or more stinkbugs per 100 plants. Applications should be made during the early morning when conditions are most favorable for thorough coverage.