EFFECTS OF INOCULATION OF BARLEY INFLORESCENCES WITH DRECHSLERA-TERESUPON THE LOCATION OF SEED-BORNE INOCULUM AND ITS TRANSMISSION TO SEEDLINGS AS MODIFIED BY TEMPERATURE AND SOIL-MOISTURE

An investigation of the location of Drechslera rer es on barley (cv. T hibaut) seeds showed that, when artificial contamination was carried o ut at the lime of flowering, all parts of the caryopsis, including the embryo, were infected by the two forms (f. teres and f. maculata) of the pathogen. An assessment was made of the possible role of abiotic f actors, including the effects of temperature and soil moisture, on the expression of the primary symptoms caused by the two forms of the pat hogen. The most severe damage was observed in dry soils (pF 3-4) at te mperatures of c. 12 degrees C. On young barley seedlings, the seed-bor ne inoculum caused coleoptile symptoms in the case of the form maculat a, whereas the form teres induced mostly foliar symptoms. Foliar necro ses may result from systemic invasion by the pathogen located in the s eed.