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Effect of Time of Inoculation with Cladosporium caryigenum on Pecan Scab Development and Nut Quality. T. R. Gottwald, Research plant pathologist, USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, P.O. Box 87, Byron, GA 31008; P. F. Bertrand, extension plant pathologist, University of Georgia, Rural Development Center, P.O. Box 1209, Tifton 31793. Phytopathology 73:714-718. Accepted for publication 6 December 1982. 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, 1983. DOI: 10.1094/Phyto-73-714.

Pecan nut clusters were inoculated with conidia of Cladosporium caryigenum on 10 dates ranging from 15 May to 11 September. Comparison of disease increase models based on a logarithmic curve-fitting regression analysis indicated that the 10 epidemics resulting from inoculations could be classified into three groups: early, mid-, or late-season. The midseason group had the greatest rate of disease increase, which may correspond to greater midseason nut susceptibility. Early season disease initiation decreased nut size, weight, percent oil, moisture, and protein content. Mid-and late-season disease initiation did not adversely affect any of these quality parameters. This indicated that the major effect of pecan scab on nut quality occurred prior to mid-June, the time of the initiation of shell (endocarp) differentiation.

Additional keywords: disease rating scale, Fusicladium effusum.