Disease occurs prevalently in the central- northern part of the state but is most severe in the extreme northern part of the state. Losses due to this disease result from loss of fruiting wood as vines die back further each year. The benzimidazole fungicide benomyl has been used for 25 years for control but does not survive long enough to afford economic control. F. lateritium does an excellent job of preventing infection by Eutypa lata when treatment of wounds with spores of the fungus are applied 7-14 days prior to infection by E. lata. C. herbarum has not resulted in the same degree of control.
Botrytis bunch rot of grape is a serious problem in many premium wine grape production areas.
Historical treatment for this disease has been the application of fungicides, often with little success particularly in years when disease was unusually severe. In 1984, we demonstrated that removal of leaves from the fruit zone resulted in better disease control than three fungicide applications. Though this practice is labor intensive and can be expensive, it has shown over the years to be the best treatment for this disease and results in increased quality factors in fruit including higher malic acid and TA, decreased K, increased brix, increased color and better wine quality. Other cultural techniques such as shoot positioned canopies, hedging and trellis types offer some degree of protection against Botrytis cinerea. Chemical control can be achieved through use of copper products such as Top-Cop or COCS dust for susceptible varieties such as Riesling and Chardonnay.