Effects of fertilization on thrips and downy mildew incidence and on the yield of onion

Abstract

The objective of this research was to evaluate the effect of fertilization with nitrogen, phosphorus and
potassium on thrips (Thrips tabaci) and downy mildew (Peronospora destructor), and on the yield of onion crop. The treatments were controls, half, one, two and four times the recommended amount of N, P2O5 e K2O. In the experiment with nitrogen the turkey manure was included to supply the recommended amount of nutrients. The onion thrips and downy mildew incidence were not influenced by the nutrients; only phosphorus had a positive linear tendency with the development of the insect. The yield increased mainly as a result of the use of phosphorus.