The sporulation-inhibitive effects of sulfadiazine on wheat leaf rust

Abstract

The effects of sulfadiazine on the infection of wheat seedlings by leaf rust, Puccinia triticina, were examined.The development of uredosori on seedlings of the highly susceptible wheat varieties is remarkably inhibited by soil application of sulfadiazine-Na salt aq. at the rate of 40mg per 100sq. cm within 2 days after inoculation. With delay in application of the sulfadrug, rust-inhibitive effect decreased rapidly. Phytotoxic secondary effects, i. e. stunting of the plants and chlorosis of the leaves, were fairy marked at the effectual dosage. The effect of application before inoculation is well maintained for at least 9 days.When wheat seedlings are sprayed to “run off” with the preparation up to a concentration of 1000ppm plus 1 per cent Tween-20 as a wetting agent, the development of sori is inhibited for some periods, but later on resumed gradually, the effect is very poor compared with that of soil application.The rust-inhibitive effects of sulfadiazine are conteracted by the supply of p-amino benzoic acid.