Pesticide management of major pests and diseases of tomato
2008
Varca, L. M. | Navasero, M. V. | Peralta, G. A. | Fabro, L. E. | Quintana, B. B., Philippines Univ. Los Banos, College, Laguna (Philippines). National Crop Protection Center
Off-season on-farm field trials showed that monitoring-based intervention using insecticide for tomato fruit worm, Helicoverpa armigera, reduced the frequency of insecticide application by at least 50% compared to the farmers' practice of weekly insecticide spray application. Another Integrated Pest Management scheme using Helicoverpa Nuclear Polyhedrosis Virus (HNPV) as an intervention was found to be an effective alternative to insecticide and may totally eliminate the use of insecticide for the control of tomato fruit worm. This was based on the results of a multi-location trials conducted in Aritao, Nueva Ecija, Liliw, Laguna and La Trinidad, Benguet [Philippines]. Except in the highlands, monitoring-based intervention using lambda-cyhalothrin and HNPV were found comparable to farmer's practice. Lambda-cyhalothrin at the rate of 10-15 mg/16 L Knapsack sprayer (label recommendation) and HNPV at the rate of 10 sup 12 polyhedral inclusion bodies/hectare or its equivalent of 10-15 infected larvae/16 L Knapsack sprayer were applied only when density of fruit worm reached 0.5 larvae/plant. However, the action threshold of 0.5 larvae/plant was found to be applicable only on lowland tomato varieties but not on highland salad tomato varieties. On-farm fungicide evaluation trials at La Trinidad, Benguet showed that both farmers' field and researcher managed plots, tomato plants survived with low to medium incidence and a very low to low disease severity due to subsequent intervention by the farmers and the researchers. The farmers used both mancozeb and chlorothalonil and metalaxyl-M + mancozeb at weekly interval and also after a heavy rainfall for a total of 12 spray applications while the researcher managed plot received a total of 6 spray applications using mancozeb alternately with Metalaxyl-M + mancozeb. Both farmer practice and researcher managed plots produced good yield compared to the untreated control. Timely monitoring and application of fungicides resulted in the reduction of fungicide application against late blight of tomatoes. Supervised pesticide residue trials (SPRT) can be used to predict the dietary exposure of consumers to pesticide residues, evaluate the persistence of the pesticide on the crop, evaluate the acceptability of the CODEX MRL at the national level and can be the basis for proposing a national MRL. SPRT for cyfluthrin, lambda-cyhalothrin and chlorothalonil showed that these pesticides are safe when at the maximum residues obtained. Theoretical maximum daily intake of tomato with highest residues obtained did not exceed the recommended acceptable daily intake of 0.02 mg/kg bw, 0.002 mg/kg bw, and 0.03 mg/kg bw for cyfluthrin, lambda-cyhalothrin and chlorothalonil, respectively. Post-harvest practices such as cooking and washing can reduce the pesticide residues in tomatoes. Washing can reduce cyfluthrin residues by as much as 68% and 71% for chlorothalonil while cooking reduced residues by as much as 47% and 99% for cyfluthrin and chlorothalonil, respectively. Storage temperatures (room temperatures and refrigerated temperatures) did not affect the reduction of cyfluthrin and chlorothalonil. There was no significant difference in residue between the two temperatures were observed.
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