Dosis óptima para Prostephanus truncatus, residualidad y fitotoxicidad de Clorpirifos metil y Deltametrina en maíz almacenado

Abstract

Optimal dose for Prostephanus truncatus, residuality and phytotoxicity of metil chlorpyrifos and deltametrine in stored maize. An important cause of loss of stored seed is the insect attack, concretely of the Prostephanus truncatus. (coleoptera: Bostrichidas) Horn. The damage this insect causes is reflected in the low germinating power of seed, reason why the optimal dose, the residual action, fitotoxicity and effective ness, of chlorpyrifos metil and deltametrine were evaluated, single and mixed insecticides with the fungi cide, to determine his efficiency against P. truncatus in maize seed stored by a period of 210 days. In order to apply these products to the seed (Panther variety), the technique of residual film was used. The seed was infested with P. truncatus, in seven monthly periods. The phytotoxicity effects were determined during a storage period of 240 days, and tests of quality (germination and vigor, under conditions of accelerated aging) per periods of 60 days were made in four dates of sampling. Three repetitions for infestation of P. truncatus and for testing the phytotoxicity of seed were made, respectively, under these circumstances: with chlorpyrifos metil at concentrations of 12 up to 96 ppm, had a mortality rate from 50 to 98 % during a period of three to four months of storage. Deltametrine caused 100 % of weevil mortality in all the storage periods. Sinergism in the mixtures of products was not observed. None of the products caused phytotoxic ity to the seed and, therefore, it did not affect germination during the periods of storage; the lost of germi nation power obtained was caused by storage periods.