Ramularia pusillaUng. andRamulaspera holci-lanati(Cav.) Lind. in New Zealand

Abstract

Abstract Ramularia pusilla Ung. was recorded on the following grasses in New Zealand:—Agrostis gigantea L., Agrostis stolonifera L., Agrostis tenuis Sibth., Anthoxanthum odoratum L., Bromus catharticus Vahl., Lolium multiflorum Lam., Lolium perenne L., Lolium perenne L. × Lolium multiflorum Lam., Lolium multiflorum Lam. × Festuca gigantea Vill., Lolium perenne L. × Festuca arundinacea Schreb., Festuca rubra L. subsp. commutata Gaud., and Poa annua L. Leaf symptoms were of the eyespot type and the dimensions of conidia in these lesions varied according to the host. Growth of all isolates on agar media was of the staling type but varied greatly in the amount of growth, colour of colony, and in the pigments secreted. Cross-inoculation studies showed that many of the isolates were capable of varying degrees of cross-infection. Isolates from the Agrostis spp. had closely related host ranges, as also did isolates from the Lolium spp. and Lolium × Festuca hybrids. Lesions caused by R. pusilla were found throughout the year on most hosts with peak infection in spring and autumn. Controlled temperature-disease studies showed that the optimum temperature for disease development was 20–24°c, with no disease at 28° and very little at 12°c. The synonymy of Ramularia pusilla is discussed and reasons advanced for considering R. pusilla and Ramulaspera holci-lanati (Cav.) Lind. distinct species.