Spore Release and Infection Periods of Botryosphaeria dothidea on Blueberry in North Carolina. T. C. Creswell, Graduate Research Assistant, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. R. D. Milholland, Professor, Department of Plant Pathology, North Carolina State University, Raleigh, 27695-7616. Plant Dis. 72:342-346. Accepted for publication 5 November 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0342.

Infections of blueberry plants wounded and exposed to natural inoculum of Botryosphaeria dothidea for one 2-wk period of the growing season were most numerous during May and June. Disease occurrence on these plants was positively correlated to log of spore count, minimum temperature, and mean temperature. The mean interval between inoculation and symptom appearance varied between 1 and 14 wk, but a majority of plants became symptomatic after 4–6 wk. Incubation times were shorter for inoculations in May than in March, April, or June. Infections occurred during most of the year, and the average incubation time was about 4–6 wk. Pruning wounds provided the greatest number of infection sites for B. dothidea. Conidia were present in rainwater during most of the year but were barely detectable for several weeks from December to February. The log of total numbers of conidia collected in rainwater was positively correlated to rainfall amount, temperature, and relative humidity during the current week. Spore counts were often more strongly correlated to temperature and relative humidity values from the previous week than to values from the current week.