Combate ao ácaro rajado Tetranychus urticae Koch, 1836 em algodão, com defensivos químicos

Com o objetivo de se verificar a ação de vários defensivos agrícolas contra o ácaro rajado do algodão, um campo experimental foi instalado. Os tratamentos e suas quantidades de ingredientes ativos, por hectare, foram: A) testemunha; B) dicofol, 369,6g; C) dicofol, 739,2g; D) propargite, 1.080g; E) silaneofane, 200g; F) bifentrina, 60g; G) abamectina, 7,2g. Resultados ótimos não foram obtidos com nenhum tratamento: todavia, o propargite mostrou resultados relativamente bons após 03, 06 e 12 dias da pulverização e a bifentrina e abamectina somente aos 06 dias. Performance of some pesticides on the control of the two-spotted spider mite on cotton was evaluated by means of a test carried out in Leme, State of São Paulo, Brazil. The following treatments and quantities of active ingredients per hectare were sprayed: A) check; B) dicofol, 369.6g; C) dicofol, 739.2g; D) propargite, 1080g; E) silaneofane, 200g; F) bifenthrin, 60g; G) abamectin, 7.2g. Six evaluations were made on leaves using stereo microscopes: 02 days before spraying and 03, 06, 12, 16 and 21 days after the application. Results obtained with propargite were relatively good 03, 06 and 12 days after spraying, whereas bifenthrin and abamectin were only effective six days after the application.