Bulletin 920 Noaemfim 195s * Chemical, Cultural and Mechanical Control 0i the *Pink llollworm LlBRAFéY APR L; wax? aa1a.;;v;£¢<2 SiT: u‘ " KYBITV'E1“1STTEY in cooperation with the UNITED STATES DEPARTMENT OF AGRICULTURE TEXAS AGRICULTURAL EXPERIMENT STATION R. DI LEWIS. DIRECTOR. COLLEGE STATION. TEXAS SUMMARY This bulletin summarizes much of the research conducted on the pink bollworm by the Texas Agric 1 Experiment Station during 1953-57. A review of the life and seasonal history of the pink bollworm is presented along with descripti damage resulting to cotton from attacks by this pest. Spring emergence records for seveial areas of the I are given. Data presented for the College Station area indicated that peak emergence of pink boll moths occurred from late May through early Iune. Emergence continued into August in every year =5 were taken except 1956. Cage tests indicated that pink bollworm infestation levels up to about SOpercent infested bolls c relatively small decreases in the value of the cotton produced. provided the infested bolls averaged less Z larvae per boll. Field experiments indicated there was a trend toward a lower dollar-per-acre retum an increase in infestation. Guthion and DDT were the most effective insecticides for controlling the pink bollworm in field s laboratory tests. Control of the pink bollworm by insecticides was done by adult mortality. reducti oviposition and death of developing embryos and newly hatched larvae. The use of defoliants delayed the build-up of pink bollworm infestation 2 to 3 weeks following defoli Approximately 150 varieties or species of cotton have been screened for pink bollworm resistance. species have been found which possess properties detrimental to pink bollworm larvae. This was evide_ by a reduction in the number of surviving larvae on Gossypium thurberi and a G. tomentosum x G. hirs (Stoneville 2B) cross and by a lengthening of the larval developmental period on G. arboreum. ' Mortalities of approximately 9O percent of the larvae remaining in the field after harvest were --" by modified stalk shredders and ensilage harvesters. Different spray nozzle arrangements and gallonages of spray per acre were tested. One nozzle row was as effective as any arrangement tested. There were no appreciable differences in control ‘ gallonages of spray ranging from 2 to 30 gallons per acre. ‘ ACKNOWLEDGMENTS Much of the data reported herein was obtained from experiments conducted in entomology d I 1953-57 by W. I. Magee and from experiments in agricultural engineering during 1953-56 by M. G. Daven; Credit for entomological investigations reported in this bulletin also is due I. R. Brazzel. D. F. Martin R. K. Williams for their data on spring emergence. host plant resistance and chemical control. I. R. Br and I. C. Gaines also contributed data to the section on yield and quality losses resulting from _~ bollworm infestations. These investigations were conducted cooperatively by the Texas Agricultural Experiment Station the Entomology Research Division. Agricultural Research Service. U. S. Department of Agriculture. portion of them was contributory to southern regional project S-37. “Pink Bollworm Control." > CONTENTS Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . , . .. Acknowledgments . . . . . . . . . . . . . . ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , _ . . V . . . . Life History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._ Nature of Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . _ . . . . . . V , . . . . . . . . . . . . . . . . . . . . Spring Emergence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . _ . . . . . . . . . , . _ . . . . . . . . . . . . . . . . Losses in Yield and Quality . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Resistant Varieties and Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . , . . . . . . . . . . . . . . . . . . . . . . , . . ChemicalControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Defoliants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . Nozzle Arrangements . . . . . . . . _ . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . , . . . . .~ . , . . . . . . . . . . . . . . . , . . . .. Cultural and Mechanical Control . . . , . . . , . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . _ . . . . . . . . . . , . , . . . . . .. Stalk Shredders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . .. Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . _ . llemical, Cultural and Mechanical Control of the Pink Bollworm Perry L. Adkisson, L. H. Wilkes and S. P. ]0hns0n* HE PINK BOLLWORM, Pectinophora gossy- piella (Saund.) has long been, of concern to farmers and entomologists across the = belt. In infested areas, the pink boll- s has caused serious reductions in the yield sicquality of the affected cotton, and over ears has been one of the most destructive insects. For example, in 1952 alone, the bollworm caused an estimated $28,000,000 ‘in a 38)-county area of South Texas (Anony- 1954 . fiCultural, chemical and mechanical control gods are used to control insects. Until the ad- of DDT, there were no effective chemical s for controlling the pink bollworms, there- i farmers relied almost entirely on such meas- ras regulated planting, stalk shredding, early esting and by plowing under the cotton deb- These methods were not completely satis- try and research for better methods of con- ing the pink bollworm were continued. This bulletin summarizes much of the work ucted during 1953-57 by the Texas Agricul- Experiment Station in search of better ways mbat the pink bollworm. LIFE HISTCRY gDetailed information pertaining to the life seasonal history of the pink bollworm has pectively, associate professor, Department of Ento- logy; associate professor, Department of Agricultural 'neering, and assistant professor, Department of Physiology and Pathology. been published by several entomologists (Ohlen- dorf, 1926; Fenton, 1928; Fenton and Owen, 1931, 1953; Owen and Calhoun, 1932; Chapman and Hughes, 1941 ; Fife, 1956; and Lukefahr and Grif- fin, 1956, 1957). The pink bollworm undergoes four developmental stages—egg, larva, pupa and adult, Figure 1—completing the life cycle in 25 to 30 days in midsummer. There may be as many as six generations in a year. ’ The adult is a small grayish brown moth. The adults are most active at night and seek shel- ter during the day, and thus, are seldom seen in an infested field. A female may lay 50 to 300 eggs over a period of about 8 days. The eggs may be deposited singly or in masses on vegetative or fruiting parts of the cot- ton plant. The preferred oviposition site is be- tween the calyx and the boll carpel. Eggs nor- mally hatch in 4 to 5 days. The larva is a small caterpillar which may attain a length of about one-half inch when full grown. In the early instars, the larva is whitish in color and usually transforms to a shade of pink by the time it attains full growth. It is this pink- ish color of the mature larva which suggests the common name of the insect. The larvae feed in- side the squares or bolls for 1O to 14 days. They then usually leave the fruiting parts of the cotton plants and pupate in the soil. These are termed “short cycle” larvae and give rise to the adults of the current year. Many larvae do not pupate im- mediately on completion of the feeding period, but remain inside the boll. These are termed dia- Figure l. Adult. egg. larvae and pupal stages of the pink bollworm. Figure 2. Rosetted bloom which resulted from pink boll- worm infestation. pause 0r “long cycle” larvae since they are in a quiescent condition 0f arrested growth. It is the diapausing larvae which survive the winter and give rise t0 the first generation of the following season. Some diapausing larvae may not pupate until in their second year of life. Most of the diapausing larvae pass the winter in the bolls in which they developed; however, some may over- winter in cottonseed, in trash in the field or at gins, or in cracks in the soil. Pupation generally occurs in the soil and about 8 days are required to complete transfor- mation to the adult stage NATURE OF DAMAGE The pink bollworm may attack squares early in the season. Usually the infested squares con- 4 tinue growth and produce blooms. Infested bl will have the petals tied together with a si thread and are commonly termed “rose blooms, Figure 2. They do not open norm This is one of the first signs of pink bollwo = festation. a Bolls are preferred later in the season. , larvae gain entrance into bolls by burrowin tunneling through the boll wall until they the lint. The entrance holes left by the larvae small, but can be detected on close examina with the naked eye. Once inside the boll, the vae may burrow through the lint searchingl the seed. This burrowing often causes stai of the lint and may weaken the fiber. Du heavy infestations, many bolls that might 0t wise have been harvested are rendered unp able as the result of pink bollworm attack. damage done contributes to losses in yield. _ is especially true if the crop is to be harv with mechanical pickers. Figure 3 shows var' degrees of damage to several bolls. f Pink bollworm larvae also will damage seed, reducing their weight, vitality and oil v tent. Increased incidence of boll rots resul from pink bollworm infestations also may tribute to further yield and quality losses. larvae on completion of development will a emergence holes to leave the bolls for pupati These emergence holes, Figure 4, similar in q to a “shot hole,” may provide an avenue for entrance of boll rot organisms under certain a ditions. Several methods of determining pink b worm infestations were used. Among these W the number of rosetted blooms per acre, perce age of bolls infested, number of larvae per y and number of mines per boll. All of these me ods were used during these investigations and = reported in the appropriate tables. i Figure 3. Degrees of pink bollworm damage to cotton bolls ranging from nearly complete destruction to no damage. 1 SPRING EMERGENCE yrds of emergence of overwintered pink ,s have been taken by state and fed- kers for many years at various lo- , Texas. Generally, these records were f by counts of the number of moths i from infested cotton placed on the pace underneath pyramidal emergence ing the fall of the year preceding each ‘These cages were fitted with small col- "bes which trapped the moths as they f’ The trapped moths were counted peri- fnntil emergence was complete. Fished records indicate that in the Pre- [a peak emergence may occur from late ,3 il mid-June, but emergence may continue ugust (Owen and Calhoun, 1932). In area, emergence may take place any- mid-March to late August. However, rs for which records were taken, up to t of the total pink bollworm emergence pleted before cotton began to bloom 56; Fife, et al 1957»). Moths may emerge “nth in the Lower Rio Grande Valley; ‘4 only those moths emerging after March pile to infest cotton of the current year. ears’ data for this area indicate that 65 ent of the total emergence normally oc- ng May; but emergence may extend into Noble, 1955). rgence records have been taken of the worm at College Station since 1954, Fig- ‘jble 1. These records are based on the of moths emerging in the spring from pfcotton which had been held under field S~ on the soil surface beneath emergence ce the previous fall. Records indicate ival of long-cycle pink bollworm larvae jollege Station area ranged from 9 to ‘- Peak emergence coincides with the Mrly fruiting period of cotton, since most oths emerged from late May through However, in all years except 1956, f} some emergence after June and moths 9 to appear in the cages to the latter ugust. The regulated cotton planting the College ‘Station area extends from to May 31, which indicates that fruit- Q will be available to a high percentage ‘ng moths. elationship of temperature, rainfall and of wintering pink bollworm larvae, as g9 by Brazzel and Martin (1958), is iFigure 5. Their results indicate that ymperatfures below 7 0° F. caused an im- eduction in the emergence of pink boll- ths. Rainfall also had an effect since rgence increased within 10 to 14 days half an inch or more of rain. Moth “e dropped sharply following 2 or 3 _a dry weather. 3 Figure 4. Pink bollworm emergence holes from infested bolls. LOSSES IN YIELD AND QUALITY Many reports have been made on the dam- age of pink bollworm infestations to the yield and quality of cotton. In some foreign countries, the insect has been credited with tremendous losses, and in 1952 caused heavy losses to the crop in parts of Texas (Anonymous, 1954). ID O O O G O MEAN TEMPERATURE b ll ~l o o o MARCH APHL MAY JUNE JULY AUQ I9 =9 =9 '9 =9 =9 '9 =9 =9 '9 =9 =9 I9 =9 =9 '9 =9 =9 20) I I I .' RAINFALL a I6 - n m4 } I I955 II I I | § _ s ~ __‘.~o 2 r _____ ‘ ~ __ ms _ o I PER CENT MQTH EMERGENCE m a _ _.__1§ ‘ ¢Z_______Jg54 |9$5 Q > ‘0__ __ ___ a’ .' u A I l I .| "-__....'.n| Il- . INCHES RAINFALL Figure 5. Fink bollworm emergence, rainfall and tem- perature records, College Station. 1954-55. TABLE l. WINTER SURIVIVAL OF LARVAE AND TIME OF EMERGENCE OF ADULT PINK BOLLWORMS AT COLLEGE STAT! 1954-57 ' I » ‘X, recovery Estimated Number oi Y b i d 1t . ear lariirlcxih jdqobed recctoiiersed survival 113512;? lune 1-30 1953-54 3,000 1,973 55.8 50.4 38.1 1954-55 11,592 10,330 93.4 32.9 42.9 1955-55 11,340 8,195 72.2 17.7 45.1 1956-57 8,220 761 9.2 91.2 I 3.8 Because the losses were determined mostly from field experiments Which often were compli- cated by the presence of other pests, such as the boll weevil, Anthonomus grandis Boh., a series of cage tests were conducted to better evaluate the losses resulting from certain levels of infestation. Much of the work by this Station has been report- ed previously (Brazzel and Gaines, 1956; 1957). Caged plots, 1/200 acre in size, were used in which the desired levels of infestation were ob- tained by periodic pink bollworm releases. Pe- riodic applications of DDT were made to main- tain infestations at desired levels. Infestations of other insects were kept at a minimum since they were prevented from entering the plots by screen cages. Results of work in 1955-56 are shown in Figures 6 and 7 taken from a report by Brazzel and Gaines (1957). These authors reported: “Heavy pink bollworm infestations caused large reductions in the value of cotton. With 100 per- cent of the bolls infested and averages of 6.4 and 9.6 larvae per boll, most of the loss in value was caused by reduced quality. When the infestation reached 12.9 larvae per boll, reduction in yield accounted for more of the loss than quality.” Under moderate levels of infestation, approx- imating those usually found in infested fields, they concluded that about two-thirds of the loss y in value of lint was the result of reduced quality I9./q INFESTED I9 LARVAE / BOLL SPRING I955 , _ ‘$2 {fQQQEESIEBLL — IOO% mrssrso IZ.9 LARVAE/ BQLL 11v. mrssrao “ L4 LARVAE/ BULL 987s INFESTED nu. ts LARVAE/ sou. I955 |00% nuresreo I 2.4 LARVAE / sou oov mrssreo 5.4 iAnvAs / sou. — O o SPRM §9."-.':'§$E.*f8.u |§ I956 . lqgvllihlizggT/EBIDOLL as '1 unresrcs 2.3 1mm: / sou. I§\\\\\\ ‘ 4O 6Q BO IOO IZO I40 I60 INFESTATION VALUE PER ACRE QUALITY LOSS Figure 6. Return ior lint in dollars per acre ior cotton produced in three experiments with various levels oi pink bollworm infestation, and evaluation oi losses caused by reduced yield and quality. ‘RETURN PER ACRE UYIELD L055 when the cotton was snapped. Lint-yield l0 occurred, but no quality losses were evident y hand-picked cotton. Losses in value of seed about equally divided between reduced yields quality. a These results indicate that pink bollwo‘ infestation levels up to about 50 percent infes bolls and less than 2 larvae per boll cause relati; ly small decreases in the value of the cotton p duced under the conditions of these experime However, these authors emphasized that these i, periments were conducted under extremely r Weather conditions which may have minimi pink bollworm damage to the cotton. Had th been at least normal rainfall, it is possible t further losses in yield and quality would have y curred as the result of increased boll rots. the cotton produced in these experiments was I grade, with the best samples taken from they p sect-free check grading good ordinary to st good ordinary. Had the cotton in the check b a higher grade, it is possible that the yield . quality losses resulting from the pink bollwo infestations would have been even more obvio There was a trend towards lowered yields I an increase in infestation. It has been thought that in wet seasons I pink bollworm may further reduce yield and q \9% INFESTED L9 LARVAE /BOLL I007 aurssrso s; 5pm,“; 5.4 lARVAE/BOLL _* IO0% INFESTEO l2.9 LARVAE / BOLL IT% INFESTED I.4 LARVAE / BOLL 98 0/0’ INFESTED FALL L9 LARVAE/ BOLL I955 IOO% INFESTED 2.4 LARVAE / BOLL IOO% INFESTED 2.4 LARVAE / BOLL -\ X‘ .\ O O 60% INFESTED I ‘ spgmg 2.4 LARVME / BULL ‘i I955 B67. INFESTED i: L8 LARVAE / BOLL 86% INFESTED 2.3 LARVAE / BOLL O 5 IO l5 INFESTATION VALUE PER ACRE I RETURN PER ACRE I3 YIELD LOSS § QUALITY L0 Figure 7. Return ior cottonseed in dollars per acre ~_ cotton produced in three experiments with various levei oi pink bollworm infestation, and evaluation oi loss. caused by reduced yield and quality. fintributing to the incidence of boll rots. this Station under laboratory conditions I that pink bollworm entrance holes into n evidently were not a factor in contribut- 1,11 rots (Brazzel, 1955); however, it is yenerally that pink bollworm emergence contribute to increased incidence of boll j dies along these lines and cage studies Wfect of different levels of pink bollworm ns on the value of cotton lint grown prinkler irrigation are beng continued to e knowledge on the relationship of in- to boll rots and cotton yield and quality. eld experiment also was conducted near tation in 1955 to evaluate the effect of infestation levels of pink bollworm on Wality and yield. Le tests used 0.1 acre randomized, repli- U Four levels of initial infestation, ‘T treated check were the designated treat- IEach treatment was replicated five times Q square design. Treatments were (1) applications of endrin; (2) 10 per- ’ ial infestation—seven applications of ‘i! (1-6) mixture; (3) 20 percent ini- tation-one application of endrin fol- six of dieldrin-DDT (1-6) mixture; (4) 3| initial infestation—three applications I followed by four of dieldrin-DDT (1-6) j, and (5) 80 percent initial infestation- ications of endrin followed by one of diel- _ (1-6) mixture. The endrin was applied te of 0.4 pound of toxicant per acre at each application, and the dieldrin-DDT (1-6) mixture at 0.4 pound of actual dieldrin, plus 3.0 pounds of DDT per acre at each application. All the insecticides were applied as sprays prepared from emulsifiable concentrates. Insecticidal ap- plications were begun on July 5 and continued at Weekly intervals to August 16. The sprays were applied with a high clearance sprayer at 60 p. s. i. traveling at a speed of 3.75 m. p. h. Damaging infestation of insects other than the pink boll- worm did not develop. Results are presented in Table 2. Reduction in yield resulting from the higher infestation levels of the check, 40 percent, and 80 percent initial infestation treatments [were statistically significant when compared with the two lower infestation levels of 10 and 20 percent. Samples of lint taken from the various treatments indicat- ed lower grades as a result of the higher infesta- tions. There was little difference in lint percent- age among the treatments. The yields and cents per pound lint values indicate a trend towards a lower dollar per acre return with an increase in infestation. There also was a trend toward more bad seed per 100 gram sample as the levels of infesta- tion became higher. Seed damage apparently was equally distributed over the plant, as indicat- ed by data obtained from samples taken from the top, middle and bottom portions of the plant. Germination tests indicated little difference in viability of intact seed taken from the various infestation levels. These data are presented in TABLE 2. EVALUATION OF SEVERAL INFESTATION LEVELS ON LINT YIELD AND QUALITY, 1955 Initial infestation Che“ 107, 20% 407,, 80% Average percentage infested bolls 10.4 2.6‘ 10.4 12.0 14.6 23.2 17.0 21.6‘ 35.0 22.2 25.6 22.4 24.8 35.6 28.6 43.2 22.8 43.8 34.0‘ 27.0 37.0 16.6 28.8 30.8 43.2 47.4 24.6 29.8 45.0 46.6 81.4 22.8 27.0 49.0 77.0‘ 90.0 45.6 39.6 52.2 89.0 44.8 23.1 28.2 36.7 43.5 - Average number of mines per 100 bolls 21.8 21.8 16.2 18.2 27.8 42.2 27.2 44.8 96.5 50.5 48.4 40.8 43.4 62.6 55.6 69.4 34.2 97.0 56.8 40.6 55.0 25.4 47.8 53.4 75.6 80.2 34.6 37.6 88.0 74.6 284.6 43.8 41.8 101.0 267.9 452.0 84.2 66.2 ‘ 112.6 392.4 131.7 39.0 49.4 73.6 123.1 Pounds of seed cotton per acre 1500 1688 1636 1452 1436 Sample grade LMEW-l- SLMEW SLM SLMEW LMEW Staple length 15/16 15/16 15/16 31/32 29/32 Value of lint. cents per pound 30.45 31.45 30.45 31.90 27.95 I v- to all applications made after this count. TABLE 3. PERCENTAGE GOOD AND BAD SEED OBTAINED FROM 100 GRAM SEED SAMPLES TAKEN FROM VARIOUS INFESTATION LEVELS Portion o/ % germi- Treqtment of plant Number of seed b 0d nation bolls G d B d d of intact taken 0° a See seed Check Top 975 39 3.8 95.6 Middle 805 24 2.9 94.8 Bottom 795 12 1.5 95.4 Total 2575 75 2.8 95.3 10% initial Top 900 3 0.3 96.3 infestation Middle 886 9 1.0 85.8 Bottom 783 9 1.1 91.9 Total 2569 21 0.8 91.5 20% initial Top 912 3 0.3 90.0 infestation Middle 800 30 3.6 95.0 Bottom 769 25 3.1 92.6 Total 2481 58 2.3 92.5 ' 40% initial Top 867 33 3.7 80.0 infestation Middle 843 21 2.4 84.4 Bottom 775 19 2.4 96.2 Total 2485 73 2.9 86.8 80% initial Top 934 16 1.7 90.4 infestation Middle 862 12 1.4 91.9 Bottom 767 53 6.5 83.7 Total 2563 81 3.1 88.6 Table 3. Results obtained from the cage tests (Figure 7) suggest that under certain conditions seed losses may be greater than indicated by this experiment. RESISTANT VARIETIES AND SPECIES The development of a commercially accepted cotton variety resistant to pink pollWorm attack has been the objective of a long-range breeding program initiated in 1954 at College Station. In- vestigations have included a search for a cotton possessing physiological resistance to pink boll- oworm and a search for any plant morphological characters which would influence the female moths to deposit more of their eggs on exposed parts of the plants rather than beneath the boll calyx. Preliminary phases of this work were re- ported in Station Bulletin 843 (Brazzel and Mar- tin, 1956). Approximately 150 varieties and species of cotton have been screened for resistance to pink bollWorm attack. In the initial screening, the cotton Was infested manually by placing a nu of Viable pink bollworm eggs on bolls of sp ages. The number of surviving larvae and y‘ ber of days required for their developm stages Were the criteria used for screening. g varieties that appeared to possess some degr resistance were then planted in 6x6x36‘ field cages and exposed to heavy pink boll infestations. These varieties were evaluate cording to the number of larzyal entrance ' per boll, larvae recovered per boll, perceny bolls escaping injury and the number and 10c of eggs deposited on the plants of the diff cottons. Three species Were found Which sessed properties detrimental to pink boll ' larvae. This was evidenced by a reductio the number of surviving larvae on Gossy thurberi and a G. tomentosum x G. hirs (Stoneville 2B) cross and by a lengthening of} larval developmental period on G. arboreum This Work was continued in 1956, as sh by the results reported in Table 4. Three s of each type of cotton tested were planted ran ly in each of four large field cages. Bolls ' tagged at 10-day intervals throughout the se beginning when the first bolls were 10 days When the first bolls were 10 to 2O days old, moths were released into each cage. Aftei days, these bolls were removed from the pl and another 150 moths released into each ' This procedure was repeated until the end of season. The bolls Were Weighed and the number location of larval entrance holes recorded. - ords also were taken of the number of larvaeli gram of boll to take boll size into considerat These tests indicated that Deltapine ‘ Stoneville 2B and Texas 42 had the greatest n ber of damaged bolls, While the G. tomentosu Stoneville 2B cross and G. thurberi had thef est injured bolls. The other cottons Were in mediate in this respect. " The most larvae per gram of boll were‘ covered from G. thurberi (a small-boll varie Texas 42 and Z74275, and fewest from thei tomentosum x Stoneville 2B cross. - The other approach to the problem was’ investigate the influence of certain plant morp logical characters on the oviposition sites sel TABLE 4. PINK BOLLWORM INFESTATION DATA SHOWING NUMBER OF LARVAE RECOVERED PER GRAM OF BOLL v PERCENTAGE OF BOLLS ESCAPING LARVAL DAMAGE, 1956 . Total Average Entrance Larvae recovered Number of % - ; Cotton bolls boll weight. holes per gram of undamaged wi -- grams per boll boll weight bolls la _ Deltapine 15 56 15.8 2 00 .071 27 4 g G. thurberi 117 0.6 0 16 .139 110 9 Texas 42 27 16.1 3.00 .129 11 40. Stoneville 2B 57 17.5 1.74 .054 32 5. G. tomentosum x 2B 18 2.7 0.11 .021 . 17 9 l Z74275 12 2.8 0 33 .117 8 75 Naurotzky ' 61 17.8 2 00 .052 38 63 8 if; female moths. Chemical control by in- gs probably would be much more effective were deposited on exposed parts of the .. The young larvae also would be more ex- the elements and to their natural enemies, ' ich might be important factors in reduc- T number of larvae gaining entrance into h It was, therefore, necessary to make f» study of the oviposit_ion sites and lar- ;vior (Brazzel and Martin, 1955, 1957). f; work along these lines was reported by ;'1917), Loftin (1921), Ohlendorf (1926) ton and Owen (1953). In general, these g»: found that the favored oviposition site green bolls and preferably beneath the Lor boll involucres. During the early part , son, before bolls have been formed, eggs sited indiscriminately over the plant. ‘rk cited from this Station confirms these ‘reports. Idy of larval behavior indicated that many ‘larvae which hatch from eggs deposited v the boll calyces enter the boll directly pot move about over the plant. These lar- ‘uld be difficult to control by ordinary It also was found that the larvae are listic and will attack each other when- ‘ey come in contact during their travels plant. Thus, a variety possessing char- hich would influence the female moths it eggs away from the bolls could serve irable adjunct to chemical or biological . or both. dies of the morphological characters of jf cottons revealed that they may have some p) - on the oviposition sites selected by the illworm. Studies along these lines were '0 during 1956-57. Six plants of each ere planted in each of the four large field Q; Squares were removed from the plants ptember 1 to allow all species to begin fruiting together. Moth releases were begun when 10-day-old bolls were present. Five re- leases of 300 moths per cage were made in 1956 and three releases were made in 1957. Five days after each release, two plants selected at random from each species were examined under a binocu- lar microscope for eggs. Results of these tests are reported in Table 5. More than 50 percent of the eggs found on Delta- pine 15 and G. thurberi in 1956 were deposited on the vegetative parts of the plants. On Pubsecent, more than 50 percent were found on the vegeta- tive ‘plant parts and the exposed boll areas. Most of the eggs on the other cottons were found under the boll calyces. ' More eggs were found in 1957 on the vegeta- tive parts of Pubsecent, Pima, G. herbaceum and G. thurberi than on the exposed boll areas or un- der the boll calyces. All the eggs found on G. thurberi were on vegetative parts. None of the cottons had as many eggs deposited under the boll calyces as on the other plant parts combined. Some varieties apparently were more pre- ferred by the ovipositing moths than others. G. herbaceum was significantly more attractive in 1956 than were the other varieties. Delta Smoothleaf was the most preferred variety in tests conducted in 1957. G. thurberi was the least preferred variety for oviposition during both years. Additional research was conducted during 1957 on varietal preference. The same cottons were planted in the greenhouse. The plants were transferred to the field before bolls formed and each plant placed in a 2 x 2-foot cage. Two plants of each cotton were tested weekly for 9 weeks by confining 20 moths on each plant. A total of 18 plants were inspected for each variety or species. All records were made before bolls were present. RELATIVE PREFERENCE BY THE PINK BOLLWORM FOR OVIPOSITION SITES UPON CERTAIN VARIETIES AND LPECIES OF COTTON WHEN CONFINED IN LARGE FIELD CAGES WITH FRUITING PLANTS OF EACH Number ot eggs 1956 1957 Vegetative Under Fruit Vegetative Under Fruit parts calyx area‘ Total parts calyx area‘ Total 301 143 91 535 1036 1045 202 2283 56.3 26.7 17.0 16.72 45.4 45.8 8.8 19.42 18 113 2 133 1698 1554 566 3818 13.5 85.0 1.5 4.22 44.5 40.7 14.8 32.52 78 163 149 390 1304 244 799 2347 20.0 41.8 38.2 12.12 55.6 10.4 34.0 20.02 167 662 10 839 1712 190 19 1921 19.9 78.9 1.2 26.12 89.1 9.9 1.0 16.42 111 1034 144 1289 627 259 94 980 8.6 80.2 11.2 40.12 64.0 26.4 9.6 8.32 17 10 0 27 401 0 0 401 63.0 37.0 0 0.82 100 0 0 3.42 ‘ 3213 11750 . I’ 2 eggs found on bracts and exposed parts of the boll above the calyx. d as a percentage of grand total egg production for the respective year. TABLE 6. RELATIVE PREFERENCE OF OVIPOSITION SITES BY THE PINK BOLLWORM WHEN CONFINED ON A SINGLE VARIETY OR SPECIES OF COTTON BEFORE BOLLS WERE FORMED, 1957 species Number of eggs or _ Axfl Total variety Terminals Leaves buds Stems Deltapine 15 196 321 274 0 791 "/, of total 24.8 40.6 34.6 0 Delta Smoothleat 210 321 430 0 961 ‘Z, ot total 21.9 33.4 44.7 0 Pubsecent 112 354 78 112 656 ‘Z, ot total 17.1 53.9 11.9 17.1 Pima 255 379 179 0 813 ‘Y, of total 31.4 46.6 22.0 0 G. herbaceum 314 151 304 0 769 ‘X, of total 40.8 19.6 39.6 0 G. thurberi 76 87 152 0 315 0 ‘X, ot total 24.1 27.6 48.3 Table 6 indicates that, even in the absence of other varieties, pink bollworm moths will de- posit relatively few eggs on G. thurberi. There was little difference in the number of eggs re- corded on each of the other cottons. Axillary and terminal buds generally were the favored ovi- position sites on all the cottons. However, on Pubsecent, 53.9 percent of the eggs were deposit- ed on the hirsute (hairy) leaves and 17 percent on the stems. Investigations to date indicate that certain cottons possess physiological or morphological characters which furnish some resistance to pink bollworm attack, either by a deleterious effect on developing larvae or by influencing the female moths to deposit most of their eggs on exposed plant parts. Some varieties also appear to be un- attractive to the females. No variety possessing both resistance and desirable agronomic charac- ters has been found, but results to date give prom- gise of a such variety in the future. CHEMICAL CONTROL Chemical control of this pest has proved dif- ficult since a large percentage of pink bollworm eggs are deposited under the boll calyces and many of the larvae enter the boll immediately after hatching and, thus, never come in contact with the insecticide. There also has been some question as to whether chemical control has been the result of larval or adult mortality. TABLE 7. COMPARATIVE TOXICITY OF GUTHION AND DDT TO THE PINK BOLLWORM‘ Pounds "/0 Mortality Per acre Guthion DDT 4.0 55 2.0 81 43 1.0 64 19 0.5 45 ‘Laboratory test where green bolls were intested with 5 eggs each. The bolls were sprayed and examined ior larvae after 10 days. Forty to 50 bolls were used tor each concentration. l0 Work at this Station in 1954 indicated t Guthion was more effective under laboratory ! ditions at the rate of 1.0 pound of actual t‘ cant per acre than DDT at 4.0 pounds (Ivy, et 1955). These results are reported in Table Tests with these two insecticides also w, conducted in the field. Dust treatments of _, and 20 percent DDT and 5 percfent Guthion W compared with an untreated chelck on randomi‘ plots of .10 acre. Each treatment was replic four times. The dusts were applied at the ’ of 15 pounds per acre. Applications were be September 1O when 7 percent of the blooms v found rosetted. Six additional applications w made at approximately 5-day intervals. t Weevil and bollworm populations were extrem low and were not considered factors affect results of the experiment, which are repo in Table 8. Plots treated with Guthion had significan fewer injured bolls than the DDT-treated check plots. There were no significant diff ences between the DDT and check plots, and. differences in grade or staple among the tr ments or the check. Subsequent cage tests were conducted to l termine the efficiency of several organic in’ ticides in controlling the adult pink bollwog (Williams, et al, 1958). These experiments 3 designed to evaluate the insecticides accord' to their effect on mortality and oviposition moths. Sprays prepared from emulsifiable c‘ centrates of the following insecticides w tested: DDT, Guthion, toxaphene, dieldrin, = drin, malathion, parathion, aldrin, benzene he chloride, heptachlor, toxaphene-DDT (2-1) m ture, dieldrin-DDT (1-2) mixture and Guthi TABLE 8. RESULTS OF FIELD TESTS WITH DDT GUTHION FOR THE CONTROL OF PINK BOLLWORM, Date ‘Y, Number of Pounds injured worms per seed co Treatment counted _ bolls 100 bolls per ~- Guthion 9/16 9/ 24 10/1 10/ 8 10/15 Average DDT 20% 9/ 16 9/ 24 10/1 10/ 8 10/15 Average DDT 10% 9/ 16 9/ 24 10/1 10/ 8 10/15 Average Check 9/ 16 9/ 24 10/1 10/ 8 10/15 Average p-l |_| s94 ' . . . . PPFPPPPFPS" cooococnnqwooacocaoowcnoaoonnoowoco asz T FF???" t wcauoaoonn~ro~z~a~u-oazon FPPPFFPPPE°P°PF°PFSDPP°PPPPLD>IF wwoocnooomoocoocwoocooocwouoocwmro cnmpaannwncocawnuzonnnn PPPISPP""" "' 91s ' 1-3) mixture. Untreated checks were _ned for comparison. "insecticides were applied as sprays to p cotton plants growing in the field at otf 21/3 gallons total spray per acre. Gen- kjnme replicate plants Were sprayed with age of insecticide. Ten pink bollworm f ere caged on each plant within 2 hours spray was applied. p r the moths had been confined on the ‘Iplants for 5 days, the percentage of mor- determined. The average number of ,r moth was determined by examining y: under a binocular microscope. _ults are presented in Table 9. Less en- uthion, parathion, malathion and dieldrin fl- essary to produce a mortality of 50 per- D 50) of the adults than DDT, While xaphene-DDT (2-1) mixture, dieldrin- 1-2) mixture and heptachlor were re- } Endrin and Guthion were the most toxic inds at very low dosages. increase in dosage of any compound ‘y was accompanied by an increase in ntrol and a decrease in egg production. lor Was an exception since increased r. did not cause reductions in oviposition, ~1 lications at normal field dosages actually } ompanied by an increase in the number . deposited per moth. When applied at afield dosages, aldrin, benzene hexachlor- heptachlor were virtually ineffective in ._..ng adult mortality and caused very little _n in oviposition. i» greatest percentage control was obtained *uthion applied at the rates of 0.25 and und of actual toxicant per acre, and from thion-DDT (1-3) mixture applied at 2.0 l of active toxicant per acre. A drastic w in oviposition was obtained with these l, . Endrin applied at rates of 0.25 and 0.50 {actual toxicant per acre gave results com- A, gith the 2.0 and 3.0 pounds per acre .1 DT. . ese data are in agreement with earlier i» Robertson (1948) Who reported results friments with DDT which indicated that of the pink bollworm was accomplished 1t mortality and a consequent reduction sition. With the exception of heptachlor, pears to be true for all the compounds ‘i addition to these tests, experiments also 1 onducted; to determine the toxicity of sev- ecticides to eggs and larvae of the pink rm (Brazzel and Gaines, 1958). 0r one series of tests, l-day-old pink boll- : eggs were placed in groups of 10 each centimeter square tabs of paper. Known trations of each insecticide, prepared by 'ng the technical grade material in ace- tone, were applied by dropping approximately 25 microliters of each dilution onto the eggs. Each group of 10 eggs was considered to be one replication. Each test was replicated five times. Insecticides tested included DDT, toxaphene, dieldrin, endrin, lindane, heptachlor, malathion, parathion and Guthion. Treated eggs were held for 5 days in vented containers. Mortality counts were made from the number of eggs that did not hatch during this period. Figure 8 indicates that Guthion and parathion were much more effective as ovicides than the other insecticides tested. Apparently complete embryonic development occurred in the treated eggs that did not hatch since development appeared to progress up to a point just prior to when normal hatching could TABLE 9. COMPARATIVE EFFECTIVENESS OF SEVERAL COMPOUNDS ON MORTALITY AND OVIPOSITION OF PINK BOLLWORM ADULTS Pounds Num- Epgegrs ‘X, _ Material techni- ber moth on ‘y, reduction cal per moths t t d control in ovi- _ acre treated 1133:‘; position DDT 1 340 3.94 52.93 81.0 2 350 2.37 59.75 89.0 3 350 1.38 77.43 93.5 Guthion 1/32 90 2.75 33.58 87.0 1/16 90 2.58 51.69 88.0 1/8 50 3.51 66.45 83.0 1/ 4 90 3.98 94.84 81.0 1/ 2 90 0.13 88.68 99.0 1 30 0.17 74.91 99.0 Toxaphene 1 90 9.51 29.42 55.0 2 90 6.39 55.15 70.0 4 90 3.56 75.53 83.0 Dieldrin 1/ 2 90 9.18 45.42 57.0 1 90 3.68 68.91 83.0 11/2 80 7.09 75.43 66.5 Endrin 1/ 8 80 6.02 62.54 71.5 1/ 4 90 2.90 85.51 86.0 1/ 2 90 1.30 80.68 93.5 Malathion 1/4 90 10.03 41.64 53.0 1/ 2 90 4.50 43.13 79.0 3/ 4 80 5.83 60.36 72.0 Parathion 1/ 8 90 13.18 51.98 38.0 1/ 4 90 7.31 48.31 65.5 1/ 2 90 2.80 71.60 87.0 Aldrin 1/ 4 30 31.43 9.49 0.0 1/ 2 90 12.59 23.95 40.0 ' 1 90 12.55 46.90 86.0 2 60 3.00 73.89 86.0 Benzene 1/ 4 20 26.00 00.00 0.0 hexachloride 1/ 2 90 12.21 32.15 46.0 1 80 8.58 40.61 59.5 2 50 4.25 73.34 80.0 Heptachlor 1/ 4 30 7.30 27.62 65.5 1/ 2 90 13.56 25.65 35.0 1 190 18.11 38.35 14.0 2 60 10.13 38.98 52.0 Toxclphene- 1 80 2.94 27.84 86.0 DDT (4-2) 2 90 5.45 36.99 71.0 4 90 2.87 69.83 87.0 Dieldrin- 1 90 4.05 23.39 80.0 DDT (1-2) 2 90 1.39 54.66 93.0 4 90 0.33 85.96 99.0 Guthion- 1 / 2 90 2.16 33.92 90.0 DDT (1-3) 1 90 0.72 62.98 97.0 - 2 90 1.03 92.32 95.0 Check 670 21.13 11 QOOI 0.0I . ' I.O I .0 PERCENT CONCENTRATION Figure 8. Dosage-mortality curves for pink bollworm eggs when treated with acetone solutions oi several insecticides. be expected. A comparison of the oxygen re- quirement of eggs treated with Guthion and DDT with untreated eggs confirmed this observation since death of the embryos in the treated eggs occurred within a few hours prior to hatching of the untreated eggs. In a second series of tests, conducted in the greenhouse, 1-day-old pink bollworm eggs were placed on 10 to 20-day-old bolls. Batches (if five eggs were placed at each of two locations beneath the boll calyces. All eggs were thus placed in protected sites. The infested plants were not treated until 3 days later. The average incuba- tion period of eggs was 4 days. Thus, most of the eggs should have hatched within 12 hours of the insecticidal applications. The plants were sprayed under a chamber at approximately 6O p.s.i Sprays were prepared from emulsifiable concentrates and were de- livered at the rate of 7% gallons of mixture per acre. Insecticides and rates of actual toxicant per acre are given in Table 10. All treatments were replicated six times. The infested bolls were collected 10 days after spraying and examined under a binocular microscope. Records were made of the number of eggs that hatched and of the number and location of larvae per boll. There were significant reductions in numbers of eggs that hatched in the Guthion l parathion treatments when compared with check, indicating the ovicidal action of these » terials. Slight reductions in the percentage eggs that hatched also were evident in the 0 insecticidal treatments when compared with checks. These reductions were not signifi _ All insecticides reducedY significantly number of larvae which entered the bolls W compared with the check. Guthion and D were the most outstanding materials in this spect. Calculation of the percentage of la, entering the bolls was made by subtracting number of larval entrance holes per boll from total number of eggs that hatched per boll. A procedure was followed to keep ovicidal ef of the insecticides from complicating the res Only those larvae which attempted to t» the bolls above the calyces were killed by in ticides. However, approximately 75 percent the larvae that gained entry into the untre bolls did so above the calyces even though eggs from which they emerged had been pl under the calyces. This suggests that though large numbers of eggs are deposited. protected sites by the female moths, some de of field control may be obtained from the tality of the young larvae which wander out; these sites before attempting entry into the l- Significantly fewer larvae were recove from the insecticidal treatments than from 1 checks. Guthion and DDT also were the effective insecticides in this respect. . Results of all the experiments cited indi A that Guthion and DDT were the most effect materials tested for pink bollworm control .4 that field control is accomplished by adult m tality, reduction in oviposition and the of developing embryos and newly hatched larv Recent experiments by the USDA Ento l ogy Research Division with Sevin (l-napth N-methyl carbamate) a new type insectici show that it is as effective as DDT for contr ling pink bollworm infestations (Bottger, et » TABLE 10. EFFECTIVENESS OF SEVERAL INSECTICIDE SPRKYS FOR THE CONTROL OF PINK BOLLWORM EGGS l LARVAE, COLLEGE STATION, 1956 Pounds Number 7 s ‘X, larvae 7° lfwlfie 7 l Insecticide technical of bolls h° egg entered en ere ° “Nae con atched above and recovered o1 per acre tested bolls below calyx1 h" DDT 1.5 90 66.1 20.2 44/56 15.1 70.5» Toxaphene 3.0 88 69.1 39.5 62/38 28.6 42.3. Dieldrin 0.3 81 70.5 44.9 71/29 32.8 34.5 Heptachlor 0.4 79 72.2 53.2 69/31 39.1 22.3 Endrin 0.4 75 69.3 39.9 70/30 28.9 41.8, BHC 0.3 80 65.8 41.3 71/29 31.0 39.7 Malathion 1.0 77 70.3 37.8 68/32 29.0 44.3 Parathion 0.25 75 60.9 32.1 69/31 22.1 53.1 Guthion 0.25 75 57.0 13.3 36/64 _ 9.1 80.6 » Check 72 79.6 68.5 75/25 - 51.5 . ‘First number represents the larvae that entered above the calyx: second figure, the larvae that entered below the calyx. 1 12 AVERAGE PERCENTAGE OPEN BOLLS ON f’ DAY AFTER TREATMENT WITH PREHARVEST F‘ l CALS AT COLLEGE STATION. 1955 ‘X, open bolls, days after treatment -1 14 21 2a _ 54.5 05.4 19.5 90.4 c“ 1e 59.4 99.0 91.0 95.4 -- 55.0 19.5 90.4 90.0 phenol 52.0 14.4 91.4 99.0 l‘ o per acre in Aminotriazole, 1 pound; Shed-A-Leaf. "ontachlorophenol. 1 gallon. 1' Cage tests indicated that 2.0 pounds 0f a, vin per acre resulted in 100 percent V, of pink bollworm moths in 24 hours plication, as compared with 78 percent .1 for 2.0 pounds of DDT. The residual g= Sevin appeared comparable with that . ge tests where first instar larvae were 2.0 pound dosages of actual Sevin and ivr acre, Sevin caused reductions of 96 in mines and 95 percent in number of _=- boll, as compared with a 64 percent Q in mines and an 83 percent reduction per boll resulting from DDT. __d experiments conducted near Browns- it 957 under conditions of severe pink boll- “a- boll weevil infestations indicated gains ypounds of seed cotton per acre from plots with Sevin, when compared with yields _ from untreated check plots (Bottger, 58). Other tests by these investigators .1 that 5 and 10 percent Sevin dusts were == effective as Guthion-DDT and dieldrin- '_tures for control of the pink bollworm. tained from these treatments were com- gland ranged up to 1,100 pounds of seed f acre greater than those harvested from feated checks. “is v use of the recommended preharvest ‘ ~ listed in Texas Agricultural Extension _7‘C0tton Defoliation Guide for Texas,” ten the opening of mature bolls for rvest and will delay build-up of pink 5 infestations approximately 3 weeks 1 defoliation. p, AVERAGE NUMBER OF WORMS IN 50 BOLL (FROM PLOTS RECEIVING PREHARVEST CHEMI- CALS AT COLLEGE STATION. 1955 _ v Number of larvae. days after treatment ~. ' -1 14 21 2a 95 " 2 0 3.8 9.5 13.7 20.3 I le 1 7 1.7 1.5 3.5 10.5 j ~' 4 7 3.0 2.3 2.2 10.2 i ‘phenol 1 0 3.5 2.3 1.8 13.8 A- es per acre: Aminotriazole, 1 gallon; Shed-A-Leaf chlorophenol, 1 gallon. TABLE 13. EFFECT OF PREHARVEST CHEMICALS ON PINK BOLLWORM INFESTATION IN BRAZOS RIVER BOTTOMS. 1956‘ Treatment, Criterion Weeks after treatment Check ‘Z, infestation 90 100 100 Mines per boll 3.3 5.0 10.0‘ Shed-A-Leaf‘ ‘X, infestation 32 36 60 Mines per boll 1.0 1.2 1.4 Sodium arsenite“ ‘Y, infestation 18 32 100 Mines per boll 0.6 0.8 4.6‘ ‘Average initial field infestation 1 week prior to treatment. 7 percent. ”Estimated loss due to infestation l0 percent. ‘Dosage rates per acre: Shed-A-Leaf. 1 gallon: sodium ar- senite. 1 gallon. ~' ‘Estimated loss due to infestation 1 percent. The effect of preharvest chemicals on boll opening is shown in Table 11. Records taken at weekly intervals indicated that there was a greater number of open bolls in the treatments than in the check and that defoliation resulted in more bolls opening earlier. The delay of build-up in infestation follow- ing defoliation, as indicated by the number of larvae found in 50-boll samples, is shown in Table 12. Samples were taken at random from the green bolls remaining in each plot. Bolls in the untreated plots were infested with approximately twice as many larvae as those in the defoliated plots at the end of the 35-day observation period. A study of pink bollworm build-up in de- foliated and non-defoliated cotton was conducted at eight locations in the Brazos River bottom during the summer of 1956. Defoliants were applied by airplane. Table 13 indicates that pink bollworm populations increased faster in the non- defoliated plots, with infestations reaching 1'00 percent within approximately 3 weeks. Gener- ally, 5 to 6 weeks were required for infestations to reach the same level in the defoliated plots. Since heavy rain frequently delays stalk de- struction and plow-up after harvest, preharvest chemicals which inhibit regrowth are important factors in eliminating or reducing the food supply for late-season generations, and thus, can reduce the number of overwintering larvae. Table 14 indicates the effectiveness of certain chemicals in inhibiting regrowth. TABLE 14. AVERAGE EFFECT OF THE INDICATED PRE- HARVEST CHEMICALS ON THE FOLIAGE OF COTTON PLANTS AT COLLEGE STATION. 1955 Material‘ ‘X, regrowth‘ Check 61.2 Shed-A-Leaf 23.2 Aminotriazole 30.4 Pentachlorophenol 23.2 ‘Dosage rates per acre: Shed-A-Leaf, 1 gallon; Aminotriazole, 1 pound: Penthachlorophenol. 1 gallon. 2Expressed as percentage recovery of original number of green leaves 21 days after treatment. 13 TABLE 15. RESULTS OF NOZZLE TEST, COLLEGE STATION, 1954-55 1954 1955 Treat Nozzles Gallons a t per per Number of _ _ Pounds of Average _ _ /, Poun men row acre larvae per myured seed cotton number of mines injured seed 100 bolls bolls per acre per lUU bolls bolls per - Check U 0 307 8U 735 7U 85‘ 13 Dust 1 15’ 153 57 805 53 54 1 p Dust 2 15’ 174 64 795 25 1i 32 1 I Spray 3 6 137 52 718 19 28 14 Spray 3 9 175 61 732 29 41 13 » Spray 3 18 153 51 740 26 35 l3 Spray 5 1U 215 61 732 22 31 13 Spray 5 15 177 58 725 29 34 14 Spray 5 3U 147 52 820 2U 3U l3 ‘In 1955. check plots were treated with 0.4 pound ot endrin per acre on a 5-day schedule. zPounds o1 dust applied per acre. From the data presented, it is evident that defoliation can play an important role in pink bollworm control programs by delaying the build-up of heavy infestations late in the season, and thus reducing the number of potential over- wintering insects. Nozzle Arrangements Work was conducted at this Station for sev- eral years to determine the most effective nozzle arrangements and gallonage for obtaining cotton insect control with ground sprayers. Previous work indicated that one hollow-cone nozzle per row calibrated to deliver 2 gallons of total ma- terial per acre was as effective as two or three nozzles per row calibrated to deliver up to 14 gallons of spray per acre (Brown and Hanna, 1954; Smith and Hanna, 1955; and Smith, et al, 1.956). Experience shows that best results in the field may be obtained by spacing cone-type noz- zles every 20 inches on the sprayer boom, as recommended in Texas Agricultural Extension “Service L-128, “Texas Guide for Controlling Cotton Insects, 1958.” Results of additional tests of various nozzle arrangements and gallonages per acre under con- ditions of pink bollworm infestations are reported in Table 15 and 16 (Magee and Davenport, 19 All plots, except the checks, were treated fl a dieldrin-DDT (1-6) mixture at the re mended rates. Applications were made W‘ in the 1954-55 tests, and at 5-day interval 1956. Spray applications were made Wit high clearance, self-propelled sprayer. D were applied with rotary hand guns at the ' of 15 pounds per acre. Infestation recordsi the boll weevil and bollworm were determ by square and boll examinations. Infestat of pink bollworm were measured by boll section in 1954-55 and by moth emergence f boll samples in 1956. i The 1954-55 tests indicate that in yields, acre, the three-nozzle-per-row spray arrange I calibrated to deliver 6 gallons per acre effective as any of the more complicated rangements in the tests. Spray and dust tr ments were about equally effective, and t’ was little difference among any of the treatme Work in 1956 was expanded to include p swath, jet-type nozzles. The jet nozzle arra ments consisted of one nozzle which was of, cover swaths up to 40 feet in width. One t nozzle per row was as effective as any of t TABLE 16. RESULTS OF NOZZLE TEST, COLLEGE STATION, 1956 Nozzles Gallons ‘Y, weevil ‘Y, bollworm Number ot Number of Poun d Treatment per of spray punctured iniured rosetted blooms worms per seed co i, row per acre squares squares per acre lUU bolls per ~7 Spray‘ 1 6 3 5 704 U.1 2200 ’ Spray" 3 6 1 4 1064 0.0 2225 Q Spraya 2 4 4 4 1604 0.2 2255 __ Spray?‘ 2 6 22 7 1470 1.0 2012 .5 Spray‘ 1 2 4 3 1666 1.4 2275 » Spray* 11 14 8 1140 11.2 1988 f Spray5 11 33 7 1844 15.6 1695 i Untreated check 34 14 1695 11.1 1145 Pink bollworm check“ 2 6 8 7 1154 17.4 ‘Nozzles spaced 40 inches apart on sprayer boom. zOne nozzle directly over row and one on each side of row on drops. “Nozzles spaced 20 inches apart on sprayer boom. *2 wide-swath iet nozzles per 40-foot swath (fieldjets). 51 wide-swath jet nozzle per 40-foot swath (boomjet). “Sprayed with U.4 pound of endrin per acre on 5-day schedule. 14 TABLE 17. MACHINE EFFICIENCIES BASED ON THE PERCENTAGE OF PINK BOLLWORM REDUCTION FOR SEVERAL TYPICAL TYPES OF MACHINES TESTED ‘X, reduction Machines 1953 1954 1955 1956 1957 Average l. Standard shredders 51.1‘ 34.6 90.2 55.2 2. Modified commercial shredder 75.4 98.5 86.9 3. Experimental stripper-crusher-l 17.3 _ 17.3 4. Experimental stripper-crusher-2 ' 85.1 98.4 91.8 5. Ensilage harvester-1 60.3 71.5 97.5 76.3 6. Ensilage harvester-2 97.5 96.7 97.1 Average number of moths per 1/ 250-acre plot 344 469 714 33 665 1m ‘Average of four stalk shredders. more elaborate arrangements. The jet-type noz- zles were not as effective as the cone-type nozzle arrangements. CULTURAL AND MECHANICAL CONTROL Even with the advent 0f the newer insecti- cides, practical pink bollworm control still is de- pendent mainly on cultural practices. Certain measures, such as regulated planting, stalk de- struction and plowing under of crop debris, still are in use and are very effective for reducing pink bollworm populations. Machinery has an important function in the present day fight against the pink bollworm. Research at this Station on cultural and mechanical control of the pink bollworm has been centered around de- veloping power-operated stalk-cutter shredders which would efficiently destroy over-wintering lfarvae harbored by the cotton residue left in the ield. Stalk Shredders Twenty machines, including commercially manufactured shredders, modified shredders and several experimental machines, were tested to evaluate their effectiveness in reducing the pop- ulations of wintering larvae left in infested cotton. Tests were located in fields which had suf- fered severe pink bollworm infestations during the growing season. Infestation records were determined by comparing the number of moths which emerged from crop residue collected be- fore and after shredding. The crop residue con- sisted of bolls left on the stalks after harvest and of cotton waste which had fallen on the ground. The residue from each plot was collected and maintained separately in special emergence cages stored in a constant temperature room. Records of the number of moths emerging from the in- fested material were/made at regular intervals until emergence ceased. The machines were evaluated according to the percentage reduction of pink bollworms. i i Results of the tests are presented in Table 17. Four commercially manufactured power- operated stalk-shredders were tested in 1953. These machines were constructed in the same manner using a vertical shaft with horizontal rotating blades. The reduction of pink bollworms ranged from 36.4 to 69.4 percent, with an average of 51.1 percent. Various modifications, such as increasing the blade speed, use of cross blades, closer spacings on the discharge grill and the use of an impact blower at the discharge open- ing, were used on machines tested during 1954. The results were generally improved, but the extra power requirements caused by these modi- fications were beyond an economical range. Close observations during the operation of the stand- ard shredders revealed that one of the reasons for inefficiency in the machines was due to the inability of the machines to pick up loose boll material from the ground. Much boll material was shattered by the machines passing over the stalks and by the shattering of the stalks from the impact of the blades. A modified lift-type blade, Figure 9, in com- bination with a discharge grill used in a con- ventional shredder (machine 2, Table 15), in- creased shreddability and gave better insect con- trol with only a slight increase in power require- ment. The suction created by the whirling blades picked up boll material from the ground which ordinarily was missed with conventional straight blades. I A stripper-crusher unit was designed and constructed in an attempt to strip and crush the residue from standing cotton stalks prior to cut- ting with a stalk shredder. The first unit con- Figure 9. Modified lift-type blade used on machine Z. Table 15. 15 Figure IO. Stripper iunit and crusher rolls used on machine 4, Table 15. structed (Figure 10) used double steel stripper rolls and a pair of 6-inch (outside diameter) steel rollers to crush the stripped material. This ma- chine was included in tests conducted in 1954, but, as shown in Table 15, its efficiency was very lOW. The steel stripper rolls were replaced with rubber-flighted stripper rolls and the crusher rolls were replaced with rubber-covered 13-inch (outside diameter) crusher rolls. These modifi- cations improved the efficiency considerably, as shown in tests conducted in 1955-56. Two ensilage harvesters also were included in these tests. Machine No. 5 in Table 5 used a cut- ting mechanism similar to a conventional stalk- shredder in that the cutting blades rotated in a horizontal plane on a vertical shaft. The housing was enclosed completely and the cut material was discharged through a wagon spout at the rear. The second harvester used a horizontal shaft with vertical rotating curved-type knives. Both ma- chines required more power, but were superior to. the standard shredders in reducing insect infestations. LITERATURE CITED Anonymous. 1954. The pink bollWorm——ho-W We fight it. USDA Leaf. 339. 8p. Bottger, G. T., A. J. Chapman, Rex L. McGarr and C. A. Richmond. 1958. Laboratory and field tests with Sevin against cotton insects. Jour. Econ. Ent. 51(2) :236-9. Brazzel, J. R. 1955. The pink bollworm as a factor in cotton boll rots. Plant. D1s. 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Amo spray per acre for the control of cotton boll weevils‘. bollworms. Tex. Agr. Exp. Sta. Frog; Rept. 1687. 5“ Busck, A. 1917. The pink bollworm, Pectinol gossypiella. Jour. Agric. Res. 9-347-70. “- Chapman, A. J. and M. H. Hughes. 1941. F, influencing the formation of resting pink bollworm la Jour. Econ. Ent. 34(4):493-9"4. . Fenton, F. A. 1928. Bio-logical notes on the I bollworm in Texas. 4th Internat’l Cong. Ent. 2:4 Fenton, F. A. and W. L. Owen. 1931. Hibern of Pectinophora gossypiella in Texas. Jour. Econ. r 24(6) :1197-1207. Fenton, F. A. and W. L. Owen. 195s. The pink worm of cotton in Texas. Tex. Agr. Exp. Sta. Misc. ; 100. 38p. i Fife, L. C. 1956. Seasonal occurrence of resting i vae of the pink bollworm in Central Texas. Jour. ‘ Ent. 49(4):562-53. Fife, L. c., c. B. Cowan, Jr. and J. W. Davis. 1 Factors influencing pink bollworm winter carryove Central Texas. Jour. Econ. Ent. 50(5):642-44. ' Ivy, E. E., J. R. Brazzel, A. L. Scales and n. F. M‘, 1955. Five new phosphate insecticides for cotton control. Jour. Econ. Ent. 48(3) :293-95. i Loftin, v. c., K. B. McKinney and W. K. Hanson. 1f Report on investigations of the pink bollworm of co in Mexico. USDA Bul. 918. 64p. i- Lukefahr, M. and J. A. Griffin. 1956. The effec food on the longevity and fecundity of pink bollw moths. Jour. Econ. Ent. 49(6):876-77. P Lukefahr, M. and J. Griffin. 1957. Mating and i position habits of the pink bollworm moth. Jour. E Ent. 50(4):487-90. a Magee, W. J . and M. G. Davenport. 1958. The e l of spray nozzle arrangement and gallonage on c0 of the pink bollworm and other cotton insects. In P ‘ Noble, L. W. 1955. Investigations of the pink ,0 worm and hemipterous cotton insects. USDA Circ. ' 15p. Ohlendorf, W. 1926. Studies of the pink bollworm. Mexico. USDA Bul. 1374. 64p. .4 Owen, W. L. and S. L. Calhoun. 1932. Biology of p pink bollworm at Presido, Texas. Jour. Econ. Ent. 25( 744-51. Robertson, O. T. 1948. Tests with DDT, benz hexachloride and ryania for pink bollworm control. J, Econ. Ent. 41(1):120-1. i Smith, H. P. and R. H. Hanna. 1955. Effects of r type and arrangement of spray nozzle on the control‘; the cotton bollworm and boll weevil. Tex. Agr. Exp. Prog. Rept. 1752. 3p. Smith, H. P., C. M. Hohn and R. L. Hanna. 19 Effects of spray nozzle types and arrangements on cot insect control. Tex. Agr. Exp. Sta. Prog. Rept. 1906. Williams, R. K., J. R. Brazzel and D. F. Martin. 19 The effect of certain organic insecticides on the morta and ovinosition of pink bollworm moths. Jour. Econ. E 51(5):567-70. "