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Discharge of Ascospores of Eutypa armeniacae in New York. R. C. Pearson, Assistant Professor, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456. Plant Dis. 64:171-174. Accepted for publication 10 October 1979. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-171.

Discharge of ascospores of Eutypa armeniacae from perithecia on Concord grape stumps in Geneva, New York, usually began less than 3 hr after rainfall started, continued throughout the rainy period, and ceased after rainfall ended and stromata dried. Water from snowmelt also stimulated ascospore discharge. Ascospores were released during each period of rainfall throughout the year, but the highest counts occurred in winter and spring and the lowest in summer. This finding is significant because winter and early spring are when grapes are pruned in New York. Ascospore counts from grape stumps collected from the field and stored on a laboratory bench showed a seasonal periodicity similar to those from spore trapping in the field.

Keyword(s): epidemiology, Eutypa dieback, Vitis labruscana.