SEARCH FOR BIOLOGICAL-CONTROL OF BARLEY N ET BLOTCH BY THE PREVENTIVEUSE OF A WEAKLY AGGRESSIVE STRAIN OF DRECHSLERA-TERES

The preventive use of a weakly aggressive strain against D. teres. the causal agent of barley net blotch, showed that the application of the mycelial suspension or of crude filtrate on the leaf lamina subsequen tly induced decreased attack by agressive strain, is reflected by the decreased number of infection sites and by the decreased size of necro ses. Barley lamina mesophyll in the presence of the toxic filtrat of t he hypoagressive strain, which was followed by inoculation with an agg ressive strain, was little allowed with respect to that of the control plants.