Insecticides for the Control of B~ollworms, Heliothis spp. on Cotton Circular March 195 1972 000 A,-I AGRICULTURAL EXPERIMENT STATION A UB U RN E. V. Smith, Director U NIV ER S IT Y Auburn, Ala~ba~ma Insecticides for the Control of Bollworms, Heliothis spp. on Cotton F. R. GILLILAND, JR. 1 COTTON BOLLWORM complex, Heliothis spp., is one of the major deterrents to profitable cotton production in Alabama and much of the cotton belt. Frequently, damaging bollworm infestations occur following early season insecticide applications for control of the boll weevil, Anthonomous grandis Boheman. Populations of beneficial arthropods that normally limit bollworm populations are greatly reduced by early season boll weevil control; thus, bollworm populations may rapidly increase to economic levels. Currently, efforts are being made to develop techniques of pest management that will take advantage of the natural enemies of various cotton pests. Until these systems of pest management are perfected, cotton producers must continue to rely on chemical insecticides as a first line of defense against Heliothis spp. From 1967 through 1969, a series of tests was conducted to evaluate insecticides for Heliothis control. The results of these tests are presented herein. 7 HE GENERAL PROCEDURES Tests to evaluate insecticides for control of Heliothis were conducted in two locations from 1967 through 1969. All tests were designed as small replicated field plots in randomized complete blocks. Insecticides were applied with a high clearance, self-propelled sprayer calibrated to deliver 5 gallons of total spray per acre. Generally, applications were made on a 4- to 6-day schedule. Test materials known to be ineffective for controlling boll weevil were supplemented with azinphosmethyl (GuthionR) at a rate of 0.25 pound per acre. 1 Associate Professor, Department of Zoology-Entomology. FIRST PRINTING 4M, MARCH 1972 Several criteria were used to evaluate the effectiveness of the test materials: (1) number of bollworm eggs per 100 plant terminals, (2) percentage of plant terminals containing live bollworm larvae, (3) percentage of bollworm-damaged squares, (4) percentage of bollworm-damaged bolls, and (5) yield data. Yield data were collected from each treatment by mechanically harvesting the center four or eight rows. These samples were weighed and the data converted to pounds of seed cotton per acre. Rainfall at the test site was monitored each year. Rainfall during July, August, and September of 1967, 1968, and 1969 was recorded as 13.49 inches, 11.78 inches, and 15.26 inches, respectively. 1967 EXPERIMENT Methods and Materials This experiment, at the Wiregrass Substation, Headland, Alabama, consisted of 10 insecticidal treatments and an untreated check, each replicated four times in plots 16 rows wide and 100 feet long. Tiers of plots were separated by 200-foot alleys. Eleven applications of materials were made, Table 1. At one point during late August, the regular 4- to 6-day application schedule was extended to 13 days. The long interval between insecticide applications was used to induce a bollworm population increase that would allow a more meaningful evaluation of the test materials. Results and Discussion The bollworm population was relatively small during most of the test; however, the extended application schedule during late August allowed an increase in the bollworm population. All materials did an adequate job of controlling bollworm infestations before the bollworm population was allowed to increase, Table 1. Following the population increase, CIBA 9491, ThuricideR, and the nuclear polyhedrosis virus did not effectively control the infestation. Based on counts of live bollworms, all other materials achieved effective and statistically equal control. Late in the test, bollworm infestations were monitored by examining bolls for damage. Two such examinations were made. Protection afforded by the insecticides was variable. Although all insecticide-treated plots had significantly fewer damaged bolls [3] TABLE 1. DESCRIPTION OF TREATMENTS, SEASONAL BOLLWORM INFESTATIONS, AND YIELD OF SEED COTTON, BOLLWORM CONTROL TEST, HEADLAND, ALABAMA, 1967' Live w Bolworm- Treatment Rates per acre' ter termi dam. boils per 10 row-ft. 4 No. 10.33 a 5.67 a Yield per acre Lb. 1,909 a Lb. No. EPN + methyl parathion----------. 0.5 + 0.25 4.39 a EPN_____________________________________ 1.0 4.41a TDE ---------------- 1.0 _________________ -- 27.llabc 9.11a 26.00 abc 37.33 ed 14.00 ab 36.22 bed 57.00 de 1,931a Am Cy 47470______________________________ 0.5 6.3Oab Azodrin_________________________________ 0.6 7.50 abc Furadan (Nia. 10242)_________________ 0.5 8.12 abc DDT___________________________________ 1.0 8.13 abc CIBA 94916__________________________________ 0.5 9.60 bcd Thuricide (IMC)_______ _---------------- 2 qt. 11.38 cd Viron/H (IMG N.P. Virus)____ 100 LE' 13.38 d Check-____-91e8 ____-6--78____---9 1 Means followed by same letter are not significantly e 4.82 a 1,911 a 64.11 e 6 1,639bcd 1,884 ab 1,607ce 1,819 abc 1,502 def 1,359 ef 1,491 def 1,331 f f 8/31. 'Application ''Based on nine counts: 8/25, 8/30. counts. Based on two weekly 8/18. 'Missed application on dates: 6/29, 7/6, 7/11, 7/17, 7/21, 7/26, 8/4. 8/%.8/14. 8/18, different at 0.05 level. 'LE - larval equivalents. than the untreated check, plots sprayed with several of the materials, particularly the two pathogenic formulations, were heavily damaged. Based on the infestation data, most of the materials did an adequate job of controlling young, early-instar bollworms feeding in the terminal of cotton plants. However, the ineffectiveness of some test materials (Thuricide, CIBA 9491, and the nuclear polyhedrosis virus) in controlling the more mature bollworms that normally infest bolls was reflected in the yield data. Thus, plots treated with these materials did not yield a statistically greater amount of seed cotton than the untreated check. 1968 EXPERIMENT Methods and Materials During 1968, 13 insecticidal materials were tested for their effectiveness in controlling the bollworm on cotton. This test, conducted at the Wiregrass Substation, Headland, Alabama, compared insecticides currently recommended for bollworm control as well as several other materials. Each treatment was replicated fou- times with individual plots 16 rows wide and 100 feet long. Tiers of plots were separated by 25-foot alleys. Applications of an insecticide (Guthion) for boll weevil con[4] trol were begun in all plots on June 20 and continued on a 4- to 6-day schedule until the test began. In order to achieve a large population of bollworms in the test area, the first application of test materials was not made until July 22. After the test was initiated, Guthion was included in the spray formulation of test materials known to be ineffective for controlling the boll weevil. Results and Discussion An examination made prior to the test indicated an average infestation of 70 bollworm larvae and 40 bollworm eggs per 100 plant terminals in the plots. Subsequent examinations of terminals during the remainder of the season indicated that all materials suppressed further bollworm population buildup. However, the large initial population was destructive to the cotton crop as indicated by the numbers of bollworm-damaged squares and bolls and yield records, Table 2. There were no significant differences in the seasonal average counts of live bollworms in plant terminals in treated plots, an indication that all test insecticides performed equally well against the early instar larvae that normally infest cotton plant terminals. However, these same materials were not equal in their protection of cotton squares and bolls, and significant differences in effectiveness were evident. Methyl parathion and seven other treatments resulted in the least amount of bollworm damage to squares. However, all test materials except Gardona (SD 8447) had fewer bollworm-damaged squares than the untreated check. All plots sustained a considerable amount of boll damage. All test materials provided some boll protection; all materials except Dursban, Gardona, and CIBA 9491 gave statistically equal boll protection. Yield records indicated the severe bollworm pressure encountered in this test. Even plots treated with materials that provided the greatest measure of square and boll protection yielded a relatively small amount of seed cotton. All insecticide-treated plots except those treated with Viron/H and Dursban yielded significantly more seed cotton than the untreated check. 1969 EXPERIMENT Methods and Materials This experiment was initiated at the Wiregrass Substation, Headland, Alabama; however, during the early growing season, [5] TABLE 2. DESCRIPTION OF TREATMENTS, SEASONAL BOLLWORM INFESTATION AND YIELD OF SEED COTTON, BOLLWOBM CONTROL TEST, HEADLAND, ALABAMA, 19681 Rates per acre' Live worms per 100 terminals' Boliworm- Treatment dam. sqs Boliwormdam i Lb. EPN +methyl parathion------- 0.5 + 0.5 Amer. Cyanamid 47470________ 0.75 No. 24.3 a 24.7 a Pct. 16.0 ab b Pct. 32.5 a 34.2 abc 40.7 be 34.3 abe 34.1 abe Lb. 907 ab 708 cd 19.0 abed 25.2 de 29.7 ef 35.3 abe 1,038 a 736 be Viron/H (IMC N.P. virus)-- -. 60 LE' 1.0 Zolone (RP 11974) Methyl parathion Guthion 2 qt. 24.7 a Thuricide (IMC)-------------------1.0 24.9 a DDT Gardona (SD 8447) 0.75 23.7 a 1.0 18.0 abed 38.2 abe 991 ------------------------------------a Supracide (CS 13005).__________ Phosvel (VCS-506) --------- 23.3 bcde 33.0 ab 24.8 a 26.2 ----------------------------a 26.5 a 15.3 ab 12.5 a a 675 cd 889 ab 1,027 a methyl parathion_____________________________ 0.25 ± 1.0 25.5 a 7 7 1.0 CIBA 9491_____________________________2 . a 27.0 a 0.5 Dursban_______________________________ 1 + ---------------1.0 26.2 a 14.5 35.7f 1.0 26.2 a 23.2 bcde 17.0 abe 32.5 ab 31.3 a 933 a 1,052 a 1,056 a 30.0 a 20.3 abed 24.5 ede ____ 57.Ob Check___________________________________ " Based on six weekly counts. on three weekly counts. 'Based on five weekly counts. LE = larval equivalents. 42.Oc 40.2 be 61.Od 981a 679 cd 533d Means followed by same letter are not significantly different at 0.05 level. 'Application dates: 7/22, 7/26, 7/31, 8/5, 8/6, 8/12, 8/16, 8/21, 8/22. 'Based inclement weather and mechanical difficulties with the spray apparatus were encountered and the test was transferred to the Agricultural Engineering Research Unit near Marvyn, Alabama. Ten insecticidal treatments were included in this test. A lack of cotton at the test site prevented the inclusion of an untreated check and standard treatment in the test. However, a related test conducted adjacent to this experiment supplied an untreated check and standard treatment for comparative purposes. Thus, test data were not analyzed statistically. All plots were 16 rows wide and 100 feet long; each treatment was replicated four times. Seven applications of the test insecticides were made at 4- to 6-day intervals beginning on August 4. Prior to initiation of the 1.0 pound per acre was applied test, Gutbion + DDT @ 0.25 three times at 5- to 6-day intervals for control of all cotton insects. All plots were treated similarly during the pre-test period; the last pre-test application of insecticide was made one week prior to the start of the test. During the test Guthion @ 0.25 pound per acre was included in all the spray formulations known to be ineffective for controlling the boll weevil. + [6] TABLE 3. DESCRIPTION OF TREATMENTS, SEASONAL AVERAGE BOLLWORM INFESTATIONS, AND YIELD OF SEED COTTON, BOLLWORM CONTROL TEST, MARVYN, ALABAMA, 19691 Live TetetRates peratacre Bolldm qam Pct. 17.5 14.5 Bollom om il per 100 periace' 3 worm om il dam. Pct. -9.2 9.0 per acre Fundal-Galecron-------------------------Guthion + DDT'-----------------------_ Lb. 1.0 0.25 + 1.0 No. 7.2 8.8 Lb. 1,992 2,097 Stauffer N-2596 -------------------------- 2,498 1.0 11.6 21.8 12.6 Bay 98820 ---------------------------------0.75 12.2 21.3 17.0 2,633 Phosvel (VCS-506) --------------------1.0 12.4 18.5 17.8 2,415 JMC Virus (VH 690) 40 LE' 14.4 28.0 18.0 2,449 CIBA 9491----------------------------------1.0 15.4 26.3 14.8 1,811 CIBA 2307 ---------------------------------1.0 16.4 29.8 19.4 2,557 IMC Virus (VH 691)-----------------40 LE' 16.6 15.5 12.4 2,356 LMC Virus (VH 69C) 40 LE' 25.8 25.5 16.4 2,118 -----------------------------------------------40 LE' 28.2 28.3 IMC Virus (VH 69M) Check2------------------------------------1 13.8 2,078 38.3 46.8 37.7 1,206 Data not analyzed statistically because two treatments were not in same field dates: nearby related test. 8/13, 8/19, 8/22, 8/27, 9/3. as other treatments. with ''ATreatments shared 8/4, 8/8, pplication equivalents. LE = larval Based on five weekly counts. ° Based on four weekly counts. Results and Discussion Boliworms were abundant during this test. Random samples of Heliothis spp. collected from the test plots dm-ing August indicated that almost half of the population consisted of H. virescens (Fab.), the tobacco budworm. This occurrence was ab- normal; in past years, the Heliothis population. during August was almost entirely the common bollworm, H. zea. Counts of live bollworms in plant terminals indicated that Fundal-Galecron was the most effective material tested, Table 3. Most of the other experimental materials were adequate on controlling early-instar bollworms in the plant terminals; however, none of the other test materials was equal to the standard (Guthion ± DDT). Counts' of bollworm-damaged squares and holls indicated a similar pattern of effectiveness. Yield data generally followed the trends established by the bollworm infestation data. However, yields from the FundalGalecron plots were not as high as expected from the infestation data. All insecticide-treated plots produced good yields despite heavy bollworm pressure throughout the test. [7] OF ALABAMA'S LAND-GRANT UNIVERSITY With allagricultural rcscarclh unit in every major soil area, Auburn tjli\ crsit\ serves the needs of field crop, live' stock, forestry, and Ihor t ictut0ridproducers . in, each region in Ala- bamia. Ev erv citicen ot o the State has a stake in this re('search proIgramnla silce anv advantage ess andi miore i X froml f economical %vavs of p)rollcing and handling farm piroducts directly benefit, the conesilling plI1ic. ® i ej i - Research Unit Identification i. 2. 3 4. 5. 6. 7. 8. 9. 10. 11. 12 13. 14. 15. 16. 17. 18. 19. 20. 21 Tennessee Volley Substation, Belle Mina. Sand Mountain Substation, Crossville. North Alabama Horticulture Substation, Cullman Upper Coastal Plain Substation, Winfield. Forestry Unit, Fayette County. Thorsby Foundation Seed Stocks Farm, Thorsby Chilton Area Horticulture Substation, Clanton Forestry Unit, Coosa County. Piedmont Substation, Camp Hill. Plant Breeding Unit, Tallassee. Forestry Unit, Autauga County Pruttville Experiment Field, Prattvill. Black Belt Substation, Marion Junction Tuskegee Experiment Field, Tuskegee Lower Coastal Plain Substation, Camden Forestry Unit, Barbour County. Monroeville Experiment Field, Monroeville Wiregrass Substation, Headland. Brewton Experiment Field, Brewton. Ornamental Horticulture Field Station, Spring Hill Gulf Coast Substation, Fairhope