EFFECT OF SUNFLOWER PLANTING DATE ON INFESTATION AND DAMAGE BY THE SU FLOWER MOTH (LEPIDOPTERA: PYRALIDAEj IN KANSAS'

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1 EFFECT OF SUNFLOWER PLANTING DATE ON INFESTATION AND DAMAGE BY THE SU FLOWER MOTH (LEPIDOPTERA: PYRALIDAEj IN KANSAS' Muhammad Aslam, Gerald E. Wilde, T. L. Harvey' and W. D. Stegmeier' Department of Entomology Kansas State Universily Manhattan, Kansas ABSTRACT Effects of planting date on sunnower moth, HonlOcosoma. eleclelum (Hulst.), infestation at Belleville, Hays, Hesston, Hutchinson, and Manhattan, Kansils were determined during under non-irrigated conditions. Sunflower, Heliallthus WUlUllS L., was planted on three dates (carly, mid-season and latel spaced at approximately 2- to 4-wk intervals from mid-may through mid-july. The number of sunflower moth larvae/head lind percent head damage caused by the larvae were recorded. The number of larvae/head and percent head damage were usually higher and seed yield lower in the early plantings. Planting sunflower in early July result.ed in lower infestation at Hays, Hesston, Hutchinson and Manhattan. At Belleville, infestations by the sunflower moth were minimized by planting sunflower oft.er the second week of June. Sunflower moth infestations may be reduced and the crop produced economically by delayed planting without significant yield loss. Key Words: Sunflower, planting date, sunflower moth. HonlOeosoma elecleljum, Lepidoptera, Pyralidae. J. Agric. Entomol. 8(2): LOI-IOS (April 1991) Higher energy costs and declining water tables have forced Kansas farmers to look for alternative crops. Because sunflower is drought tolerant (McMullen 1985) it has drawn considerable interest as a potential alternative crop in Kansas (DePew 1983). According to Lamond et al. (1985) there is also interest in using sunflower 8S a double crop following wheat. Sunflower acreage in the state increased from 26,000 ha in 1982 to 78,000 ha in A large number of insect pests infest sunflower. Walker (1936) reported 66 insect species on sunflower in Kansas. Insect pests were identified as the most important constraint limiting sunflower production in Kansas in the Sunflower Position Update Conference, 1981 (Anonymous 1981). The sunflower moth, Homoeosoma electellum (Hulst), is the major sunflower pest in Kansas. Various workers (Carlson 1967, 1975), Teetes and Randolph 1968, 1969, 1971, Archer et a1 1983, DePew 1983, 1988) have reported that insecticides can effectively contl'o) this pest. However, multiple applications often are needed for effective management because ovipositing female moths are present in the field (or several weeks and larvae from freshly oviposited eggs enter the seeds a few days after hatching (Cadson 1967, Teetes and Randolph 1968, 1969, 1971). Chemical control is costly and may be ineffective if improperly timed. Consequently, alternative methods are being investigated for effective and economical control of this pest. 1 Received for fjublication 7 June 1990; accepted,) October Port Hay!; Branch E"periment Stalion. Hays, Kansas

2 102 J. Agric. Entomol. Vol. 8, No.2 (1991) An important cultural practice is to plant the crop so that sunflower moth activity does not coincide with sunl10wer bloom. A number of studies have indicated that larval infestations can be reduced by changing planting dates. In Nebraska, lower infestation was reported following a 2 May compared with a 8 June planting (Muma et aj. 1950). According to Teetes and Randolph (1971) sunflower planted on 12 March or after 25 April in Texas had the lowest infestation of sunflower moth among six planting dates extending from 12 March through 15 May. In another Texas study, Mitchell et a!. (1978) reported higher larval infestations in sunflower planted in March and early April than sunflower seeded in late April through May. The 14 April-planted crop in Georgia had less infestation of sunflower moth than sunflower planted on 26 May (Beckham and Tippins 1972). No information has been report.ed on sunflower moth infestat.ions in Kansas in relation to planting date. This study was undertaken to determine the sunflower moth density and damage to heads of sunflower planted at different dates. MATERIALS AND METHODS The study was conducted under non-irrigated conditions at Belleville, Hays, Hesston, and Manhattan during and at Hutchinson, Kansas during These locations represent the sunflower growing areas in the state. Planting was done on three different dates each year from mid-may to mid-july (Table 1). The planting dates, from early to late, are referred to as the first, second and third planting. At Hays, one oilseed hybrid (Dahlgren 855) was planted in 8-row plots during 1986 and 1988, and in 12-row plots during Rows were 7.2 m long and 90 em wide. Four oilseed hybrids (Texas Triumph 557DW, Cargill 208, Dahlgren 855, and Seedtec 317), which were already being evaluated in Kansas for other agronomic traits, were planted at all locations in except Manhattan in Only two hybrids (Texas Triumph 557D\V and Seedtec 317) were planted at Manhattan in 1986 due to field space limitations. Each hybrid was planted in two 9-m rows, 76 em apart. Plots in the three planting dates were separated by four non-experimental rows. Six border rows were planted on the outer sides of the experimental plots. At Hays, the experiments were conducted in a randomized complete block design with foul' replications. A split plot design with three replications was used at other locations with planting dates as the main plot and hyblids as subplots. Plots were thinned at growth stage V4, i.e., four-lear stage (Schneiter and Miller 1981) to approximately 20 cm plant spacing to obtain 58,000 plants per hu. At all locations except Hays, foul' sunl10wer heads were randomly cut from each plot at growth stage R6-7 (Table i), i.e., when nowering was complete (ray nowers wilting and the back of the head tuming pale yellow) (Schneiter and Miller 198i). Heads were bagged, brought to the laboratory, stored in a cold I'oom at 4.4 C and processed as soon as possible. Heads were quartered, the larvae were counted in one randomly selected quarter and the number of larvae/head calculated. At Hays, Jive heads were randomly cut from the center two rows of each plot at gl'owth stage R6-7. Heads were cut in half, the lalyae counted, and the number of larvaelhead was calculated.

3 ASLAM el al.: Planting Dal.e and Sunflower MOlh 103 Table 1. Sunflower planting dates and date when crop reached R6 7 growth stage in Kansas, Date Year and Location Planting R6-7 stage 1986 Belleville 29 May 13 June 29 August 17 July 17 September Hays 16 May 24 July 12 June 19 August 3 July 8 September' Hesston 2 June 12 August 17 June 1 September 3 July 24 September Manhattan 3 June 14 August 18 June 25 August 18 July 15 September 1987 Belleville 8 June 20 August 26 June 11 September 10 July 17 September Hays 19 May 31 July 13 June 25 August 7 July 22 September Hesston 5 June 12 August 22 June 1 September 13 July 24 September Hutchinson 3 June 17 August 25 June I September 8 July 24 September Manhattan 6 June 19 August 18 June 25 August 2 July 15 September 1988, Belleville 7 June 25 August 21 June 16 September 8 July 29 September Hays 20 May 2 August 24 June 30 August 14 July 29 September Hesston 6 June 24 August 23 June 8 September 7 July 23 September Hutchinson 8 June 23 August 24 June 12 September 8 July 23 September Manhattan 9 June 26 August " not recorded. 24 June 12 September 'i July 20 September

4 104 J. Agric. Entomol. Vol. 8, No.2 (1991) Larvae were not recorded in the first planting at Belleville in 1986 because poor germination did not provide enough heads for sampling, and in the third planting at Manhattan in 1986 because samples were lost when a cold room malfunctioned. Head damage was visually assessed at maturity at all locations except Hays on five random heads in each plot based on the percent of the head covered with webbing and frass. Yield data were not recorded at Hays due to heavy lodging. In 1987 and 1988 yield was obtained by randomly cutting, drying, and threshing five mature heads from each plot. Yield was calculated in 1986 from three planting dates at Hesston and two planting dates at Manhattan and Belleville. The yield in the 18 June planting at Manhattan and 29 May planting at Belleville was not recorded due to severe bird damage and poor and uneven germination, respectively. The seed yield/ha was calculated based on the plant population obtained after thinning to 58,000 plantslha. Data for hybrids were pooled and analyzed as a randomized complete block design because of inconsistent differences in number of larvae/head between hybrids. Data fol' percent head damage were transfoimed by arcsin before analysis. Data were analyzed using a general linear model in 1986 and analysis of variance procedures in 1987 and 1988 (SAS Institute 1985). Mean separation was accomplished using the least significance difference test. For all tests, results were considered significant at P < RESULTS /986 At Hays, Hesston and Manhattan, the number of larvae/head was significantly higher in the first than second planting (Table 2). The number of larvae/head was not significantly different between the second and third planting at Belleville and Hesston, whereas at Hays, the second planting had a significantly higher number of l8ivae/head than the third planting, Table 2. Mean number of sunflower moth larvae/head, head damage, and yield of sunflower planted on different dates in Kansas, 1986.*' T Head damage Yield Location Planting date Lalvae/head (%) (kg/ha) Belleville 29 May 13 June 8a 38a 3162 a Hays 17 July 1 a 18 b 1349 b 16 May 336 a 12 June 75 b 3 July 2 e Hesston 2 June 331 a 57 a 1449 b 17 June 4b 49 b 2235 a Manhattan 3 July Db 6c 2237 a 3 June 155 a 85a 1930 a 18 June 5b 36 b 18 July Dc 1462 a Means followed by the same leiter in columm within cach loclltion urc nol ~ignificlllltly different (P 2: 0.05, LSD; SAS Institute 1985). t " not recorded.

5 ASLAM et a1.: Planting Date and Suntlower Moth 105 Percent head damage \I,.'as significantly higher in the second than third planting at Belleville, Hesston and Manhattan. At Hesston and Manhattan, the first planting had significant higher head damage than the second planting. The seed yield was significantly higher in the second than third planting at Belleville. At Hesston, the first planting had significantly lower yield than both the second and third plantings. Yield was not significantly different between the later two plantings. At Manhattan, no significant difference in yield was found between the first and third plantings, the only two dates in which yield was recorded The number of larvae/head was significantly higher in the first than the latter two plantings at all locations except Hesston (Table 3). At Hesston, the number of larvae/head was significantly higher in the second than first and third plantings, which were not significantly different. The number of larvae/head was significantly different between the second and third plantings at Belleville and Hays. At Hutchinson and Manhattan, the second planting had significantly higher number of larvae/head than the third planting. Table 3. Mean number of sunnower moth larvaelhead, head damage and yield of sunflower planted on different dates in Kansas, 1987.*' t Location Planting date Larvae/head Belleville Hays Hesston Hutchinson Manhattan t 8 June 26 June 10 July 19 May 13 June 7 July 5 June 22 June 13 July 3 June 25 June 8 July 6 June 18 June 2 July 175 a 6b I b 47 a 3b 40 b 61 a 36 b 28a 19b 7c 49 a 25 b 6c Head damage (%) 93 a lib 3b 70 a 52 b 51 b 79 a 51 b 26 c 82 a 38 b 5c Yield (kgfha) 2074 a 1489 b 1145 b 1314 c 3979 a 2957 b 1335 c 1895 b 2448 a 2585 a 2784 a 2537 a Means followed hy the same leller in columns within each loclltion are not significantly different (P ~ 0.05, LSD; SAS Instilutc 1985)... not recorded. Percent head damage was significantly higher in the first than second plantings at all locations. Percent head damage was significantly higher in the second than third planting at Hutchinson and Manhattan. At Belleville and Hesston, head damage did not differ significantly between the later two planting dates.

6 106 J. Agric. Enlomol. Vol. 8, No.2 (1991) Significantly higher yield was recorded in the first, second and third plantings at Belleville, Hesston and Hutchinson, respectively. Higher yield in the early planting in spite of higher number of larvae/head at Belleville may be due to the fact that very heavy infestations had destroyed and caused the heads to fall on the ground. The sampling fol' yield was done from the heads left in the field, i.e., with less infestation. The first planting resulted in the lowest yield at Hesston and Hutchinson. No significant difference in yield was found among planting dates at Manhattan Significantly more larvae/head were found in the first as compared to the later plantings at all locations except Hesston (Table 4). The number of larvae/head was not significantly different in the second and third plantings at Belleville, Hays, and Manhattan. At Hutchinson the second planting had significantly more larvae/head than the third planting. At Hesston, the number of l8ivaelhead was significantly higher in the second planting than in the first or third plantings. Significantly more lalvaelhead occurred in the first than third planting. Table 4. Mean number of sunflower moth lalvae/head, head damage and yield of sunflower planted on different dates in Kansas, 1988.*' t Location Planting date LalVae/head Belleville Hays Hesston Hutchinson Manhattan 7 June 21 June 8 July 20 M.y 24 June 14 July 6 June 23 June 7 July 8 June 23 June 8 July 9 June 24 June 7 July 78. 2b b 89. 2c b I c 32 a 3b Head damage (%) 93. l 1 b b 1 b b 1 c b I c Yield (kg/h.) 1741 b b b 2142 a Meuns followed hy the same letter in columns within each loclltion are not significantly different (P ~ 0.05, LSD; SAS Institute 1985). t " not recorded. Percent head damage was significantly higher in the ru'st than second or third plantings at Belleville, Hutchinson and Manhattan. Significantly more head damage occurred in the second than third planting at Hutchinson and Manhattan. At Belleville, head damage was not significantly different between the second and third planting dates. At Hesston, the third planting had significantly less head

7 ASLAM et al.: Planting Date and SunHower Moth 107 damage than the first and second plantings, which did not differ significantly. No significant difference in yield \\'as noted among planting dates at Manhattan. DISCUSSION The number of larvaelhead and percent head damage were higher in the early or first planting at all locations in all years except at Hesston during 1987 and 1988, where larvae/head were significantly higher in the second than first or third planting dates. The reason for the higher percent head damage in the early plant.ing at Hesston, where larval numbers were lower than in the second planting, may be due to the presence of the Rhyzopus hend rot disease which has a strong association with the sunflower moth (Rogers et al. 1978). Moth larvae are known to predispose heads to disease infection (Klisiewicz 1979). The presence of the disease makes the head unsuitable as a host and some larvae left the head before larval sampling. Heads affected by Rhizopus were recorded only in L988. At Hesston, 52% of the heads were damaged by Rhizopus in the first planting as compared to 16 and 4% in the second and third plantings, respectively. The decline in number of larvaelhead in the mid to late June plantings suggests that flowering in t.he second or third planting (which occurs late August to early September) coincides with reduced moth activity. Similar results have been reported by Teetes and Randolph (1969, 19(1). In their Texas studies, late planted sunflower had significantly fewer sunflower moth larvaelhead than early plantings. 05eto et at (1989) also reported that seed damage by banded sunflower moth. Cochylis hospes Walsingham, may be reduced by delayed planting. At Belleville, planting from mid-june to mid July resulted in reduced sunflower moth infestations and head damage, and higher yield in two of the three years. At Hesston, planting after the lirst week of June resulted in lower infestation and higher yield in all three years. At Hutchinson, July planting resulted in lower infestations and head damage and higher yield. At Manhattan, infestations were reduced but yield was not affected by late planting. Based on the number of larvaelhead and head damage it can be concluded that sunflower moth infestations may be reduced by delayed planting. These results indicate that mid-june to early July plaming of sunflower in Kansas, as compared t.o normal mid-may to early June planting, will I'esult in lower moth infestation with no significant loss in seed yield. This practice will result in economical production of sunflower in the state by reducing 01' eliminating insecticide application costs. If it is widely adapted, moth phenology changes should be followed to see if lheir emergence and flight also changes in accordance with the planting date. ACI(NOWLEDGMENT We arc t.hankful to C. Swullow. M. Claassen. R. Honey nnd W. Herr for their help in conducting this study. This puper is a contribution No J from Kansas Agricultural gxperimcn\. Stat.ion.

8 108 J. Agric. Ent.offiol. Vol. 8. No.2 (1991) REFERENCES CITED Anonymous Minutes of the meeting. Sunflower Position Update Conference, 26 Feb. 1981, Manhattan, Kansas, 6 pp. Archer, T. L., C. S. Manthe, C. R. Rogers, and E. D. Bynum, Jr Evaluation of several insecticides for the control of the sunflower moth. Southw. Entomol. 8: Beckham, C. M., and H. H. Tippins servations on sunflower insects. J. Econ. Entomol. 65: Carlson, E. C Control of sunflower mot.h lalvae and their damage to sunflower seed. J. Econ. Entomol. 60: Pesticides for controlling sunflower moth larvae. Calif. Agric. 29: DePew, L. J Sunflower moth (Lepidoptera: Pyrnlidac): oviposit.ion and chemical control of larvae on sunflower. J. Eeoll. Entomol. 76; Suppression of sunflower moth (Lepidoptera: Pyralidae) on sunflower with selected insecticides. J. Kans. Entomol. Soc. 61: Kligiewicz,,1. tv! Relation of infestation with sunflower moth,!iomoeofioma electellum, larvae to the incidence of Rhizopus rot in sunflower seed heads. Can. J. Plant Sci. 59: Lamond, R. E., L. C. Bonczkowski, D. L. Figurski and J. P. Shoyer Doublecropping with sunflowers. Cooperative Extension Service, Kansas State University Agricultural Fact Sheet AF 127, Manhattan, 3 pp. McMullen, M. P Sunflower production and pest management. North Dakota Agricultural Experiment Station Bulletin 25 (Revised), Fargo, 76 pp. Mitchell, T. L., E. D. Bynum, C. R. Ward, G. L. Teetes, C. A. Scheffer, and R. D. Brigham Sunflower pest population levels in relation (0 date of planting on the Texas high plains. Southw. Entomol. 3: Muma, M. H., R. N. Lyness, C. E. Claassen, and A. Hoffman Control tests on sunflower insects in Nebraska. J. Econ. Entomol. 43: Oseto, C. Y., L. D. Charlet, and J. D. Busacea Effect of planting date on damage caused by the banded sunflower moth (Lepidoptera: CochyJidae) in the northern Great Plains. J. Eeon. Entomo!. 82: Rogers, C. K, T. E. Thompson, and D. E. Zimmer Rhizopus head rot of sunflower: etiology and severity in the southern plains. Plant Dis. Rep. 62: SAS Institute SAS user's guide: statistics, version 5 ed. SAS Institute, Cary, North Carolina, 956 pp. Schneiter, A. A., and F. J. Miller Description of sunflower growth stages. Crop Sci. 21: Teetes, G. L., and N. M. Randolph Chemical control of the sunflower moth on sunflowers. J. Econ. Entomol. 61: Chemical and cultural control of the sunflower moth in Texas. J. Rcon. Entomol. 62: Effects of pesticides and dates of planting sunflowers on the sunflower moth. J. Reon. Entomo!. 64: Walker, F. H., Jr sen:ations on sunflower insects in Kansas. J. Kans. Entomol. Soc. 9: