How Can I Minimize Plant Disease Problems Next Year?

The growing season is over and most of us are taking a break from gardening. However, there are a few key actions you can take now to minimize disease problems in your garden next year:

• Practice good sanitation. Remove all infected plant debris from the garden now, before the ground is covered in snow or the debris disintegrates. Prune back perennials, such as peonies, to remove any infected leaf material. Infected debris can be burned (in the country) or disposed of with community yard waste (in the city). Since most home compost piles do not heat up to the proper temperature to kill pathogens, it's best not to put diseased debris there.
• Prune oak trees now (late fall) or early in the spring. During the growing season, particularly April through June, nitidulid beetles are active and can carry the oak wilt fungus to fresh pruning wounds. Pruning oaks only during the dormant season is the best way to prevent oak wilt, a lethal disease of oaks.
• Take notes on where annual plants (such as tomatoes or peppers) were located in your garden this year, so you can plan to rotate crops next year. Many plant pathogens overwinter in crop debris on top of and in the soil. Most pathogens only attack one or a few closely related plants. Planting next year's tomatoes in a spot that did not have tomatoes this year can help to avoid exposure to the overwintering inoculum.
• Choose disease-resistant varieties when ordering seeds for next year. Starting with resistant plants can help to avoid some diseases altogether, or at least minimize disease problems.

Pruning back diseased peonies helps prevent disease next year.