Leaf Spot and Foot Rot of Kentucky Bluegrass Caused by Helminthosporium Vagans ' '

In an abstract ^ published in 1922 the writer reported the widespread occurrence on Kentucky bluegrass {Poa pratensis L.) of a leaf spot caused by a species of Helminthosporium. Often, especially in moist situations, the lesions had been found on the leaf sheaths at the base of the plants as well as on the blades, giving rise to a condition comparable to foot rot of wheat. A brief account of the parasite, containing a discussion of its distribution and its pathological effects in addition to its description under the name Helminthosporium vagans Drechs., was included the following year in a paper'* dealing with various forms parasitic on grasses. Except for a report by Gardner ^ stating that leaf spot of June grass due to H. îngans was prevalent at La Fayette, Ind., during May, 1923, the hterature seems to offer no information concerning the disease in which the parasite involved was referred to by the binomial mentioned. However, Monteith ^ reported that the leaf-spot disease of bluegrass had been destructive in fairways of golf courses in New Jersey and Pennsylvania during the early part of June, 1924. Although in the text the causal fungus was not cited by name, its identity was indicated in the statement that it was ''closely related to those causing stripe, net blotch, spot blotch, and similar serious diseases of various grain crops." In a second paper '^ by the same writer extensive browning of bluegrass caused by the same leaf spot was noted as having occurred during May of the following year on some golf courses in the vicinity of Washington, D. C, and on the plots at the Arlington Expofiment Farm, Rosslyn, Va. While the illustrations of severely affected leaves accompanying the text of the latter account appear altogether characteristic of those attributable to H. vagans, it may not be amiss to add that specimens of the diseased grass that formed the basis of Monteith's two reports had been submitted to the present writer for examination and the cause of the trouble had been determined as the parasite under consideration by microscopic inspection of the conidiophores and conidia present on the better developed lesions. At the time the description of Helminthosporium vagans was drawn up^ the writer's observations were limited to the development of the fungus on Kentucky bluegrass growing in fields or in lawns cut only