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Phenology of Comandra Blister Rust in Arkansas. W. E. Dolezal, Graduate assistant, Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701; F. H. Tainter, associate professor, Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701. Phytopathology 69:41-44. Accepted for publication 17 July 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-41.

The Comandra blister rust fungus, Cronartium comandrae is a macrocyclic, heteroecious rust fungus that is an obligate parasite of some hard pines (Pinus spp.) and the genus Comandra (Santalaceae). In Arkansas, rupture of aecial peridia of C. comandrae on pine was associated with the passage of a cold frontal system. Aecia cast spores for approximately 1 wk in mid-April. Uredia were first visible on comandra 8 days after the initial release of aeciospores. Early infections were restricted to lower portions of the comandra plants. As surrounding vegetation grew in height, new infections developed higher on the comandra. The passage of another cold frontal system in midMay favored the uredial repeating stage and was followed by a notable increase of uredia in late May on upper portions of the plants. Telia first appeared on 11 May, with the increase inincidenceparalleling that of uredia, but telia reached maximum development after a 7-day lag. Maximum germination of teliospores followed the passage of another cold front on 2324 June. After 24 June telial production declined. July was hot and dry and the comandra population defoliated completely during this time. Pycnia were evident on the pine host by late August and actively continued to exude pycniospores through mid-November.