DYNAMICS OF MAJOR PESTS OF SOYBEAN UNDER DIFFERENT DATES OF SOWING.
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Date
2017-08-11
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Dr.PanjabraoDeshmukhKrishiVidyapeeth, Akola.
Abstract
The present investigation entitled “Dynamicsofmajorpests of soybean under different dates of sowing’’ was carried out on Experimental Farm of Agricultural Entomology, Post Graduate Institute, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola (MS), India, during Kharif, 2016 to study the effect of different time of sowing on major pests, natural enemies, growth and yield of soybean under protected and unprotected regimes.
The result revealed that infestation of girdle beetle, stem fly and counts of semilooper, tobacco leaf eating caterpillar and sucking pests (leafhopper & whitefly adults) and lady bird beetle (adults and grubs ) revealed significant differences among the protected regime (A1) and unprotected regime (A2) and different dates of sowing (B). The minimum infestation of stem fly was registered in the crop sown at 12th July and it was at par with 22nd July and 2nd August. While,the infestation of semilooper and girdle beetle was minimum at crop sown during 22nd July (B4) followed by 2nd August (B5) and 12th July (B3). The infestation of tobacco leaf eating caterpillar was reported to be minimum in the crop sown at 22nd June (B1) followed by 2nd July (B2). However minimum infestation of leafhopper and whitefly adults was recorded in the crop sown at 12th July (B3) and it was at par with 22nd July(B4), 2nd August (B5) and 22nd June (B1). The population of lady bird beetle was highest in the crop sown on 2nd July (B2) followed by 22nd June (B1).
Among the various interactions (AXB), minimum infestation of girdle beetle (3.45 per cent) was noted in the interaction i.e crop sown at 22nd July with protected regime (A1B4) andstem fly (2.70 per cent) was noted in the interaction i.e crop sown at 12th July with protected regime (A1B3)..Minimum infestation of semilooper (0.45 larvae/mrl) was recorded in the interaction i.e. crop sown at 02nd August with protected regime (A1B5) andtobacco leaf eating (1.02 larvae/ mrl). was recorded in the interaction i.e. crop sown at 22nd June with protected regime (A1B1) .Minimum infestation of leafhopper (0.56 no./leaf) and whitefly (0.56) was recorded in the interaction i.e crop sown at 02nd August with protected regime (A1B5).The chemical insecticides used in this study revealed deleterious effect on lady birdbeetle population.
The data on various growth parameters (height, number of branches, leaves and leaf area) pertaining to different dates of sowing (B) revealed significant differences among each other at various phonological stages (flower initiation ,pod initiation and pod development). However, maximum height of plant, number of branches, leaves and leaf area was registered in the crop sown at 12th July (B3) followed by 2nd July (B2) and 22nd June (B1).
The number of pods , grains, weight of grains and yield was significantly higher in protected regime than unprotected regime.The higher pods (65), number of grains (146.88), weight of grains (13.25 g) and yield (23.81 qt/ha) was recorded in the crop sown at 2nd July (B2) followed by 22nd June (B1).Among the interactions (AXB) highest number of pods (65), highest number of grains (146.88), highest weight of grains and highest yieldwas recorded in the crop sown during 02nd July with protected regime (A1B2) followed by 22nd June with unprotected regime (A2B2) and at par with 12th July with protected regime (A1B3).
Description
A field experiment on Factorial Randomized Block Design was conducted with protected and unprotected regims (A), different dates of sowing (B) and its interactions. The sowing of crop was done at 10 days interval starting from 22nd June to 2nd August, 2016. The sowing of soybean (Var.JS. 335) was performed as per treatments and replicated 4 times. The observations on defoliators (semilooper and tobacco leaf eating caterpillar) stem tunnelar (girdle beetle and stem fly) sucking pests (leafhoppers , whitefly adults) and natural enemies (lady bird beetle), were recorded at weekly interval as per standard methodology. Whenever the pest attained economic threshold level in any of the replications, foliar application of recommended chemical insecticides were undertaken in protected regime (A1) and no chemical insecticides where used in unprotected regime (A2). The effect on growth parameters ( number of leaves, leaf area, number of branches and height of plant) was also noted at different phonological stages of crop ( flower initiation, pod initiation and pod development stage). Similarly grain yield and yield parameters ( number of pods, number of grains and weight of grains) were also recorded after attaining physiological maturity of crop the crop.
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Citation
BALORE, BHIMASHANKAR PANDURANG.(2017). Dynamics of major pests of soybean under different dates of sowing.Department Of Entomology, Dr.PanjabraoDeshmukhKrishiVidyapeeth, Akola. M.Sc. 2017. Print. xii,79p.(Unpublished).