EFFECT OF FUNGICIDES AGAINST RUST DISEASES OF WHEAT IN DEPENDENCE ON THE APPLICATION TECHNIQUE .1. MODEL EXPERIMENTS

In model experiments on winter wheat, defined quantities of Bayleton, Desmel and Corbel were applied locally at different sites of plants du ring the 3-leaf-stage respectively after spike-emergence-period. The b est effect against yellow rust and brown rust (Puccinia striiformis an d P. recondita f. sp. tritici, resp.) was achieved even with reduced d osages by application of the fungicides into the axil of the leaf to b e protected. Treatments of the leaf tip resulted successfully only wit h the recommended rate. The uptake of these fungicides was not influen ced by the droplet size (100-mu-m, 180-mu-m, 250-mu-m). At reduced dos ages, the surface tension of the spray volume interferred with disease control. At a dosage of 5-mu-g a.i., the tested fungicides demonstrat ed a considerable efficacy by vapor activity.