VIEW ARTICLE

Ecology and Epidemiology

Effects of Winter and Spring Pruning and Postinoculation Cold Weather on Infection of Grapevine by Eutypa armeniacae. A. T. Trese, Former graduate research assistant, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824, Present address: Department of Plant Pathology, University of Florida, Gainesville 32611; D. C. Ramsdell(2), and C. L. Burton(3). (2)(3)Professor of plant pathology, and USDA, ARS, research plant pathologist, respectively, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Phytopathology 72:438-440. Accepted for publication 27 July 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-438.

Field experiments involving pruning mature Vitis labrusca ‘Concord’ grapevines and inoculation of the pruning stubs with Eutypa armeniacae were conducted near Lawton, MI. Eight pruning and inoculation dates were tested in 1978 and 1979. Temperature and rainfall were monitored for 2 wk following pruning and inoculation. When 1-, 2-, or 3-yr-old wood was pruned and inoculated the same day, age had no significant effect on susceptibility. Mean percentages of infection (all dates of inoculation included) for 1-, 2-, and 3-yr-old pruned wood were 13.3, 14.3, and 15.2%, respectively. Uninoculated control vines, which were pruned at the same time as the inoculated vines, had a small amount of infection (0.5–2.0%). Control vines probably were infected by windblown ascospores from diseased vineyards 0.8 km away. Pruning 22 February and 30 March 1979 resulted in significantly (P= 0.05) greater percent infection (42 and 20%, respectively) than the six other dates (9 March 1978 through 20 December 1978), which ranged from 2 to 11% infection. In general, the greater the percentage of the 2-wk period following pruning and inoculating that the temperature was 5 C or lower the less was the resultant percentage of infection.