Charles Gardner Shaw

Peronosclerospora species and other downy mildews of the Gramineae.

SUMMARYThe subgenus Peronosclerospora of Sclerospora is raised to generic rank and described, The following species are transferred from Sclerospora into Peronosclerospora: S. dichanthiicola, S. ma...

Spread, intensification, and upward advance of dwarf mistletoe in thinned, young stands of western hemlock in Southeast Alaska

Examinations of 206 young western hemlock trees growing beneath residual trees infected with hemlock dwarf mistletoe (Arceuthobium tsugense) in two thinned stands were made from 1981 to 1987 to evaluate disease spread and intensification. The percentage of trees infected increased over this period, as did the number of infections on 79% of the trees that were infected in 1981. However, few of the infected trees had three or more infections and only eight trees had 10 or more infections by 1987. The probability of a tree being infected was significantly greater if the tree was in the understory before logging rather than having become established in the understory after logging. There was no significant orientation by distance or direction of infected trees from the infected residual trees (.)

A New Genus of the Meliolaceae on the Roots of Solanum Species

A superficial blackening of the fibrous root system of potatoes, Solanum tuberosum L., has been observed annually since 1944 (1, 3) in a series of crop rotation plots at the Irrigation Experiment Station, Prosser, Washington. Although conspicuous on the fibrous roots, the mycelium has never been observed on the tubers or on above-ground parts of potato plants. It has been reported previously (1, 3) that this discoloration is due to a dense reticulum of dark brown hyphae of a fungus that is apparently an undescribed member of the Meliolaceae. Since most of the known species of this family occur on the leaves of tropical plants, the occurrence of a black mildew (5) on roots in a temperate region prompted detailed study of its morphology and taxonomic relationships.

Root disease threat minimal in young stands of western hemlock and Sitka spruce in southeastern Alaska

(...) Heterobasidion annosum survived less than 5 yr in naturally infected stumps of either species. The high rainfall and associated high water content of stumps and low temperatures common to the region appear to limit colonization by H. a. In contrast, stump colonization by Resinicium bicolor and presumably saprophytic Armillaria spp. was common, but mortality in adjacent trees was rare (...)

Notes on the Genus Ceriospora in India

In November 1975, an ascomycete on the leaves of cardamum, Elettaria cardamomum (L.) Maton (Zingiberaceae), was collected at Cherambane, Coorg district, where the average rainfall is ca. 5,000 mm per yr. This fungus belongs to the genus Ceriospora Niessl (Pyrenomycetes, Sphaeriales, Amphisphaeriaceae), erected by Niessl in 1876. Ceriospora dubyi Niessl, on Humulus lupulus L. Cannabinaceae), is the type species. Ainsworth (1971) incorrectly limited the distribution of the genus to temperate regions; three species have been described on different genera of Palmae from South Europe and North Africa, South India, and Australia (Miiller and von Arx, 1962). Four species have been reported from India: Ceriospora arecae Menon, found on the leaflets of Areca catechu L. (Palmae) affected by yellow leaf disease (Menon, 1959; Muller and von Arx, 1962); C. lantanae Tilak & Kale on Lantana camara L. (Verbenaceae) (Tilak and Kale, 1967); C. prinsepiae Ramachandra Rao on dead stems of Prinsepia utilis Royle (Rosaceae) (Ramachandra Rao, 1971); and C. acaciae Kale & Kale, on dead stems of Acacia leucophloea Willd. (Leguminosae) (Kale and Kale, 1972). The measurements given by Muller and von Arx (1962) for C. arecae are much larger than those in Menons (1959) original description (perithecia 100-140 ,m in diam, versus 46-70 width x 52-70 um height; asci 72-80 x 12-14 tm versus 30-58 x 4.6-6 pm; and ascospores 23-28 x 5-6 Mam versus 12-24 x 3-4 um). Menon does not mention whether asci are bitunicate or unitunicate. Miiller and von Arx (1962) retain this species in Ceriospora, indicating that they consider the asci unitunicate.