Avaliação da eficiência dos fungicidas fludioxonil + metalaxyl-m no tratamento de sementes de sorgo

Abstract

This work was carried out in order to evaluate the efficiency of several fungicides applied as seed dressing in the control of sorghum seedborne fungi and the protection against soilborne fungi. Sorghum seeds of cultivar BR 506 were treated with the following fungicides (doses in g a.i./100 kg of seeds): fludioxonil + metalaxyl-M (2.5 + 1.0), fludioxonil + metalaxyl-M (3.75 + 1.5), colorless fludioxonil + metalaxyl-M (2.5 + 1.0), colorless fludioxonil + metalaxyl-M (3.75 + 1.5) and thiram (140.0). Seeds without fungicide treatment constituted the check. The following characteristics were evaluated: seed health (deepfreezing method), seedling emergence in sterile soil (green house), seedling emergence in sorghum monocropped soil (green house) and cold test in sorghum monocropped soil (laboratory and green house). The analyses of the results (Tukey at 5%) showed that: 1- the fungicide thiram was effective in the control of Fusarium subglutinans associated to the sorghum seeds, but ineffective against Aspergillus spp.; 2- fungicides fludioxonil + metalaxyl-M, colorless fludioxonil + metalaxyl-M and thiram were effectively in the controlled Penicillim spp., Alternaria tenuis, Phoma sorghina, Curvularia lunata and Drechslera turcica; 3- all fungicides had a positive effect on seedling emergence due to the protection against pathogenic fungi associated to sorghum seeds, and 4- all the fungicide treatments increased the seedling emergence in sorghum monocropped soil due to protection of seeds against soilborne fungi.