For varieties that are susceptible to botrytis, a spray containing Rovral or Vanguard is applied at cluster tightening, against veraison and after wet weather during ripening. Black rot will no longer infect the fruit after veraison, but Botrytis bunch rot becomes a problem as the cluster ripens. Both mildew diseases can become severe in the summer if they are established early. Warm humid days with heavy dews will quickly spread the disease through a vineyard. The major insect pests of grapes in SW Michigan are climbing cutworm, grape flea beetle, grape berry moth, phylloxera, rose chafer, Japanese beetle, and grape leafhopper.
Minor pests are grape root borers and European red mite.
Danitol is a pyrethroid that has just been labeled in grapes. It looks like it will be good against all grape insect pests. Insecticides are applied with the bloom sprays to control the first generation of berry moth and rose chafer. This insecticide application is also used again after bloom to control grape berry moth, Japanese beetle and grape leafhopper. Lots of Lannate is used because it is cheap and effective.