WATER AGAROSE MEDIUM FOR STUDYING FACTORS AFFECTING GERMINATION OF CONIDIA OF AMPELOMYCES-QUISQUALIS

On water agarose conidial germination of Ampelomyces quisqualis was gr eatly enhanced in the presence of powdery mildew conidia. AU seven spe cies of powdery mildews tested, representing five genera, were effecti ve in increasing germination of the mycoparasite. Aqueous extract of c onidia of Oidium euonymi-japonicae was also stimulatory to the mycopar asite. Germination of conidia of A. quisqualis on water agarose decrea sed as conidial concentration increased. Germination of the mycoparasi te's conidia at a low concentration on wafer agarose was greatly decre ased when they were separated by a polycarbonate membrane from conidia of the same species at a high concentration and incubated. After bein g incubated with conidia of the mycoparasite at a high concentration, water agarose became inhibitory to germination of conidia of the same species at a low concentration, suggesting the presence of a diffusibl e self-inhibitor. Water agarose is essentially free from nutrients whi ch may support growth of contaminants that interfere with the effect o f stimulators or inhibitors.