Selection of the proper disease resistant variety and the use of good cultural practices may eliminate the need for early season fungicide sprays. All trees should be pruned normally and receive a thorough dormant oil spray during the late winter or early spring. Plum curculio attacks the apples before the fruit are large enough to bag. Additionally, codling moth can lay eggs on the fruit prior to bagging. So before bagging, gardeners should apply an insecticide, such as Imidan, for control of plum curculio and codling moth at the petal fall stage and again two weeks later.
Petal fall is when all of the petals have fallen off of the blossoms.
Organic growers may select Rotenone to control plum curculio. These would be the last pesticide applications of the year. This will help to produce large fruit and encourage return bloom next year. The fruit can be thinned at the same time that the apples are bagged. This should be about three weeks after petal fall.