POPULATION DYNAMICS OF VARIOUS SPECIES OF THRIPS ON DIFFERENT HOST CROPS AND THEIR CHEMICAL CONTROL
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Date
2000
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AAU, Anand
Abstract
Studies were carried out on (i) population dynamics of thrips, Scirtothrips dorsalis Hood, Thrips tabaci Lind. and Kdegalurothrips usitatus Bagnall on chilli, cotton and pigeonpea respectively (ii) screening of different genotypes/cultivars of chilli for their resistance to S. dorsalis (iii) bio-efficacy of different recommended synthetic insecticides against different species of thrips infesting chilli, cotton and pigeonpea and (iv) curling intensity in chilli against thrips, S. dorsalis protected with recommended synthetic insecticides during 1998-99 to 1999-2000. The activity of S. dorsalis on chilli was started from 3rd week of October '98 and continued till 2nd week of January '99 during first year while during second year, it was observed during 1st week of September '99 to 1st week of January, 2000. The thrips, S. dorsalis showed negative correlationship with minimum temperature, mean vapour pressure and mean relative humidity. While the activity of T. tabaci was foimd on cotton leaves starting from 2nd week of August during both the years and continued till 1st week of January '99 during first year and 2nd week of November '99 during second year. Windspeed, minimum temperature and mean temperature showed positive correlationship with population buildup of T. tabaci. In case of M. usitatus infesting pigeonpea, the activity started from 1st week of October '98 during first year and 2nd week of October '99 during second year and continued till 1st week of December during both the years. The thrips, M. usitatus had significant negative correlationship with mean temperature. The chilli ACS-92-4 and G-4 found less susceptible to thrips, S. dorsalis, whereas both tlie local chilli cultivars Jwala and S-49 were found to be most susceptible among all the genotypes/cultivars tested. However, both the local chilli cultivars Jwala and S-49 proved to be with higher yield potential. Need based application of triazophos 0.04 per cent, monocrotophos 0.04 per cent and acephate 0.075 per cent on chilli S-49 managed the infestation of S. dorsalis effectively and economically in middle Gujarat agroclimatic condition, while in case of cotton H-6 and pigeonpea GT-100 need based spray of methyl-o-demeton 0.025 per cent was found most effective along with triazophos 0.04 per cent, acephate 0.075 per cent and phosphamidon 0.03 per cent against thrips. The chilli S-49 protected with triazophos 0.04 per cent against thrips, S. dorsalis had the lowest incidence of leaf curl followed by crop protected with acephate 0.075 per cent.
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AGRICULTURAL ENTOMOLOGY, AGRICULTURE, A STUDY