Factors affecting spore germination and initial growth of Pseudocercosporella herpotrichoides on wheat

Abstract

Wheat coleoptiles inoculated with Pseudocercosporella herpotrichoides spores were much more susceptible to colonization and infection than first leaf laminas. It is unlikely that susceptibility was due to a lack of chlorophyll, since fungal colonization of plants grown at low light intensity to induce chlorosis was similar to that of plants grown under normal lighting. Similar numbers of spores were found on first, second and third leaves of seedling plants of wheat exposed to natural inoculum from crop debris on a field site. Spore germination on agar was insensitive to light, but very sensitive to changes in water potential; at — 27 bars 95 % of the spores germinated but at potentials below — 41 bars only 63 % germinated. Germination on agar was not affected by changes in spore concentration over a range of 1.5 × 10 3 to 5.2 × 10 6 spores ml −1 .