Thrips tabaci management in organic onion using diatomaceous earth

Abstract

The objective of this work was to evaluate of the effect of diatomaceous earth on incidence of thrips, the yield and mean bulb weight in onion on organic system. The research was carried out during August to December of 2004 and 2006. In 2004, the treatments were sprays of diatomaceous earth 1%, 2%, 3% and untreated check. In 2006, the treatments were diatomaceous earth sprays at 1% and 2%, and the powder distribution in the planting furrow in dosis of 40 kg/ha by 30 days after transplanting (DAT) and 45 DAT; 60 kg/ha by 30 and 45 DAT; 20 kg/ha by 30 and 45 DAT; 30 kg/ha by 30 and 45 DAT and untreated check. The randomized block design was used with four replicates. The diatomaceous earth did not consistently reduce the thrips densities, nor did not influence the yield and mean bulb weight. The correlation between insect densities and yield and mean bulb weight was not significant, thus suggesting the possibility of growing onion on organic system without use of the natural insecticides on the thrips management.