Monitoring of the occurrence of onion thrips (Thrips tabaci) on onion and their influence on yield
1996
Bocak, L. (Statni Kontrolni a Zkusebni Ustav Zemedelsky, Olomouc (Czech Republic))
The occurrence of onion thrips (Thrips tabaci) was observed on onion plots. Two various methods of assessing population levels of T. tabaci were used. Populations on three plots with different spray regime were evaluated. The first plot was sprayed every 14 days regularly, the second according to the economic threshold estimated to be 5 thrips per plant provisionally the third plot was left without any chemical treatment. Regular applications of lambda-cyhalothrin keep the low infestation during the whole vegetation period. No statistically significant differences were found in the yield depending on the number of thrips. But the yield of protected plots was 12.8 % (regular treatment) or 10.2 % (one treatment) higher when compared with the untreated plot. The field method of assessing thrips population recorded between 45 and 75 % of thrips until the beginning of July, as compared with a more accurate laboratory method.
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