From OSU Extension Office
To produce top-grade tree fruits, professional growers follow a complete spraying routine like the 13-step schedule shown below. Home Gardeners may be willing to settle for less than perfection, but even they will probably need to apply at least the basic sprays to get an edible crop. Because the times at which flowers and fruits form vary from year to year, spraying is scheduled not by the calendar but by key stages of blossom development. These stages, and the type of spray to use at each one, are indicated for various types of fruit trees in the chart below; at the bottom of the chart are the insects and diseases controlled by the sprays, with the span of time each is apt to be in evidence.