Fungous diseases of ryegrasses in New Zealand

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Abstract
A further seven fungous diesases of Lolium spp. occurring in New Zealand are described. Of these, Phytophthora sp., Ustilago striiformis (Westend.) Niessl, Urocystis agropyri (Preuss) Schroet., and Ligniera pilorum Fron & Gaillat are recorded in this country for the first time. A Phytophthora sp. causing leaf lesions and floral proliferation is widespread but of minor importance on ryegrass. Sporangiospores are abundant but oospores have not been found. Ustilago striiformis causing Stripe Smut on ryegrasses is relatively common but infected leaves are not readily apparent in a sward. Urocystis agropyri occurs on ryegrass but is not common. Ligniera pilorum was found attacking the roots of ryegrasses in several parts of New Zealand and in one newly sown field appeared to be causing the death of many seedlings. Corticium fuciforme (Berk.) Wakef. is relatively common in pastures during autumn but is seldom of economic importance, possibly because of the high nitrogen status of soils at this time of the year. Blind-seed disease incited by Gloeotinia temulenta (Prill. & Delacr.) Wilson, Noble, & Gray may in years of severe infection reduce seed germination by up to 50%. Lolium multiflorum Lam. and “Grasslands Manawa” ryegrass are less severely affected. In most years the disease is of minor importance. The effect of environment on the fungus and methods of controlling Blind-seed disease are discussed. Ergot caused by Claviceps purpurea (Fr.) Tul. is common in pastures, especially in the wetter parts of the country. Seed cleaning dresses out most of the sclerotia, and so this disease is not regarded as being as serious as Blind-seed disease.

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