A QUANTITATIVE INOCULATOR CAPABLE OF INOCULATING CEREAL PLANTS AT ALLGROWTH-STAGES WITH RUST UREDINIOSPORES

An inoculator, designed to quantitatively apply a spore/oil mixture on single stems or leaves of cereal plants, was constructed and tested. The tests consisted of counting urediniospores of Puccinia graminis f. sp. tritici applied to a glass slide, or counting uredinia that forme d on seedling leaves and adult plant stems of susceptible or several d ifferent resistant genotypes of Hordeum vulgare, or susceptible Tritic um aestivum. Using 2-mg spores suspended in 1 mt of light mineral oil, urediniospores were applied to glass slides at the rate of 125-224 sp ores/cm(2), with coefficients of variation between 7 and 22. In plant tests, distinctions between resistant and susceptible genotypes could be made using quantitative inoculations, when qualitative differences were not detectable.