SEASONAL OCCURRENCE OF MAJOR INSECT PESTS AND MANAGEMENT OF COB BORER, Helicoverpa armigera (Hubner) ON MAIZE
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Date
2016
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Indira Gandhi Krishi Vishwavidyalaya, Raipur
Abstract
The present study entitled “Seasonal occurrence of major insect pests and management of cob borer, Helicoverpa armigera (Hubner) on maize” was conducted during kharif 2015-16 at the Research cum Instructional Farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.). Regarding the seasonal occurrence of insect pests on kharif maize, seven insect species viz., maize cob borer, Helicoverpa armigera (Hubner), pink stem borer, Sesamia inferens (Walker), tobacco caterpillar, Spodoptera litura, hairy caterpillar, Euproctis spp, maize aphid, Rhopalosiphum maidis (Fitch), leaf hopper, Pyrilla perpusilla, green stink bugs, Nezara viridula, and three natural enemies viz., rove beetle, lady bird beetle and spider were observed on maize during kharif season.
Seasonal occurrence of maize insect pests revealed that the cob borer, pink stem borer and tobacco caterpillar appeared during first week of August while maize aphid, leaf hopper, hairy caterpillar and green stink bug appeared during 36th SMW (9 to 15 Sep.), 37th SMW (16 to 22 Sep.), 38th SMW (23 to 29 Sep.) and 40th SMW (7 to12 Oct.) with varied level of population respectively. The peak activity of cob borer, hairy caterpillar, maize aphid and green stink bug observed on 40th SMW of October while the peak activity of pink stem borer, leaf hopper and tobacco caterpillar observed during 37th SMW and 39th SMW of September month, respectively. The results of the correlation studies of weather parameters and maize insect pests revealed that the larval population of cob borer, leaf injury by pink stem borer, green stink bug, leaf hopper, tobacco caterpillar, maize aphid and hairy caterpillar showed non-significant positive and negative correlation with weather parameters. The pink stem borer dead heart per cent damage showed significant negative correlation with wind velocity only. Cob borer (% cob damage) showed significant positive correlation with maximum temperature, sun shine hours and significant negative correlation with evening relative humidity, respectively. The occurrence of natural enemies in the maize field was observed during kharif 2015-16. The spider, coccinellid and rove beetle population appeared during August to September month and reached peak on September to October month during kharif season. The population of spider showed significant positive correlation with minimum temperature, morning relative humidity and evening relative humidity.
The 22 maize hybrids were screened against maize cob borer, Helicoverpa armigera under field condition the minimum mean per cent cob damage (16.67%) per plant was observed in the genotype PAC-751. The minimum mean percent length of cob infestation (16.70%) was observed in genotype NK-30. The minimum mean percent kernel damage (4.39%) was observed in genotype Pro Agro and the grain yield (q ha- 1) was significantly higher in PAC-751 (34.41 q ha-1), whereas the maximum mean per cent cob damage, mean percent length of cob infestation, percent kernel damage and lower grain yield (q ha-1) was observed in genotypes DKC-9141, D-4244 and Kohinoor Delax with varied level.
In the studies of relative efficacy of different botanicals against cob borer, Helicoverpa armigera. The minimum cob borer was recorded in plots treated with Neem oil (0.30), NSKE (0.30), Karanj oil (0.30) followed by Karanj seed powder (0.40), and Chilli garlic solution (0.43). The least effective treatment with the maximum cob borer larvae recorded with Chilli solution (0.67/cob) however, it was significantly superior over untreated control cob borer larvae (1.27) per cob.
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