Alternative Gramineous Hosts of Leptosphaeria nodorum Including Two New Records for the U. S. A.

Abstract

Abstract Leptosphaeria nodorum was isolated from various wheat sources (seeds, seedling, straw, and volunteers) and from triticale, little wild barley, ryegrass, smooth bromegrass, aegilops, quackgrass, Bermuda grass, and air. The level of seed contamination in wheat cultivars varied from 3–63%. Initial detection of the pathogen from field samples of plant material varied from 5–58%. Four out of the 12 plates exposed to the air showed growth of the pathogen. The presence of spores from aerial sporetrapping decreases to zero by 30 December. The pathogen was undetected from the leaf samples of wheat and triticale from 15 January to 15 February. Spore size and cultural growth differed among the various isolates. Isolates from wheat straw, Bermuda grass, little wild barley, and triticale were fluorescent variable while the other isolates fluoresced under NUV light. Symptoms were induced when wheat cv.‘Callahan 513’ and four other grasses were inoculated with isolates of L. nodorum from various gramineous sources. The infection by the pathogen on ‘Callahan 513’ was greater than the infection of the same isolates in their gramineous weed hosts. Ryegrass and Bermuda grass were demonstrated as additional alternative gramineous hosts of L.nodorum in the United States.