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Ecology and Epidemiology

Sporulation by Cronartium quercuum f. sp. fusiforme on Loblolly and Slash Pine. E. G. Kuhlman, Principal plant pathologist, USDA Forest Service, Southeastern Forest Experiment Station, Forestry Sciences Laboratory, P.O. Box 12254, Research Triangle Park, NC 27709; Phytopathology 71:345-347. Accepted for publication 8 August 1980. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/Phyto-71-345.

Aecial sporulation by Cronartium quercuum f. sp. fusiforme occurred on an average of 76% of the galls in a slash pine plantation in South Carolina and on 65 and 44% in two loblolly pine plantations in North Carolina in four successive springs. Spermatial occurrence during three successive falls averaged 58% for the three plantations. Aecia appeared 10–13 days earlier on the South Carolina slash pine than on the North Carolina loblolly pine, whereas spermatial appearance was 12–14 days earlier on loblolly pine. Recurrent sporulation for five to seven of seven seasons was least frequent in the northernmost plantation. Most galls produced both aecia and spermatia, but some produced only one or the other during the 4-yr study. The average aecial appearance was 6–26 days before emergence of susceptible oak leaves. The major cause of gall death was natural pruning of shaded branches. Branch galls made up 73% of the dead gall population, but only 27% of the total gall population.