Abstract
Flea beetles are the most destructive insect pests of cotton in Northwestern part of Ethiopia. Damage is the most severe when seedlings are attacked and may necessitate extensive resowing. A field experiment was carried out in Metema districtfrom June to December in 2007 cropping season to estimate yield losses due to cotton flea beetle and to determine the efficacy of seed dressing and foliar insecticides against Podagrica puncticollis. The treatments were arranged by using RCBD with three replications. Seeds were treated with seed dressing insecticides (Cruiser 350 FS and Apron Star 42 WS) 5 days before sowing and foliar insecticide treatments (Sevin 85% WP and Endosulfan 35% EC) were applied 5 and 10 days after seedling emergence. No significant differences were observed among treatments in the number of flea beetles per plant before spraying with foliar insecticides. However, significant differences (P < 0.05) were observed among treatments in infestation of flea beetles before and after spray with foliar insecticides, indicated by the number of flea beetles after spray with foliar insecticides and the number of holes per damaged leaf. Plots sown with seeds treated with Cruiser, plots sown with seeds treated with Cruiser plus foliar spray with Sevin or Endosulfan 5 days after seedling emergence and 2 times spray of Sevin or Endosulfan 5 and 10 days after seedling emergence gave the least number of flea beetles per plant (1), infestation and showed less symptom of flea beetle damage with the least number of holes per damaged leaf (15) as compared to the other treatments which gave similar results to untreated check (22 flea beetles and 55.2 holes). Significant differences (P < 0.05) were observed among treatments in some agronomic characteristics of cotton. Plots sown with seeds dressed with Cruiser combined with foliar spray with Sevin or Endosulfan 5 days after seedling emergence showed significant differences and gave more number of leaves per plant (81), maximum plant height (95.2 cm), no reduction of plant stand per plot and more seed cotton yield (0.49 kg) of all the other treatments, whereas, seeds dressed with Apron Star solely and seeds dressed with Apron Star plus foliar spray with Sevin or Endosulfan 5 days after seedling emergence gave the least results and no differences were observed as compared to untreated check in some agronomic features of cotton (38 leaves, 58.1 cm and 0.1 kg). A seed cotton yield loss of 75.51% was recorded in untreated plots as compared to seeds treated with Cruiser plus foliar spray with Sevin 5 days after seedling emergence. Using Cruiser as a sole seed dressing insecticide and supplementing those seeds treated with Cruiser by foliar spraying with Sevin 5 days after seedling emergence provided the most reasonable management approach for cotton flea beetle.
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