Application methods and dosages of thiamethoxam in thrips control on tomato plants

Abstract

Thrips is one of the most important vector species of the tomato spotted wilt tospovirus (TSWV) in Brazil. Two different pesticide application methods, drench x spray, using thiamethoxam were compared with commonly used insecticides for thrips control in tomato plants, Debora Plus. The experimental design consisted of a complete randomized block design with seven treatments and four replicates. Dosages of 150 and 200 g of a.i. per ha were used in just one drench application and 50 g of a.i. ha-1 sprayed, at weekly intervals, 48 days after sowing. The control efficacy of thiamethoxam was compared to diafenthiuron (400 g of a.i. ha-1), profenofos + cypermethrin (320+32 g of a.i. ha-1, respectively) and methamidophos (60 g of a.i. per hectolitre of water) in spray application. Cumulative number of plants with tospoviruses and the F. schultzei population from ten flowers per plot were registered. The mean cumulative number of plants with tospoviruses among treatments was not significantly different. No significant difference between thiamethoxam application methods and dosages on F. schultzei control, 24 days after application, were observed for thrips population. One drench application of higher dosages of thiamethoxam proved to be more environmentally advantageous than the pesticide applied at dosages of 50 g of a.i. ha-1 at weekly intervals. The vector control efficacy of thiamethoxam varied from 93 to 95%, independently of the application method and dosages. Diafenthiuron and profenofos + cypermethrin showed less efficacy (78 and 88%, respectively) but greater than those with methamidophos (71%). The products and dosages tested did not cause phytotoxicity in tomato leaves.

USE OF THIAMETHOXAM, ASSOCIATED WITH INSECT POPULATIONS IN PAPAYA (Carica Papaya Linnaeus) CULTIVATION

“…For the control of thrips (Frankliniella schultzei Trybom) in tomato crops, in Sao Paulo, Brazil, a dose of 150 to 200 g i.a. ha -1 of thiamethoxam was evaluated, applied in a drench form, with efficiency higher than 93% and a residual effect of 24 days [25]. The Diabrotica bivitulla and Diabrotica speciosa in Brazil are one of the main vectors of the Papaya Lethal Yellowing Virus (PLYV) [23].…”