Pyrenophora teres. [Descriptions of Fungi and Bacteria].
Abstract A description is provided for Pyrenophora teres. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Primarily barley, but also occurs sporadically on wheat, oats and many other Gramineae. DISEASE: Causes net blotch of barley. Primary infection occurs from seed-borne inoculum and produces lesions on the first leaves, which are at first pale but develop into dark spots or streaks later. Secondary infection on older leaves produces pale brown blotches, in which is a network of dark brown lines; these may later coalesce to form irregular leaf stripes. Lesions also occur on the floral bracts. On other hosts the reticulate pattern of the lesions is usually absent. GEOGRAPHICAL DISTRIBUTION: Worldwide; occurs in most barley-producing countries (CMI Map 364, ed. 2, 1968). TRANSMISSION: The disease can be seed-borne as mycelium or conidia, but can also over-winter on crop debris. Perithecia are common on old barley stubble in the spring and ascosporic inoculum can produce much infection (49, 116). Secondary infection by air-borne conidia occurs throughout the growing season.