Removing diseased plant material this fall will help prevent disease problems next spring. Many disease-causing organisms can survive the winter in infected plant debris. Plowing or tilling under crop debris can also help prevent overwintering.
There are many common leaf diseases that good sanitation practices will help control. Leaf spot of iris, leaf blotch of peony, black spot on rose, blights on tomato, and scab on apple are just a few examples. If leaf spot problems were evident this year, it is a good idea to remove the plant debris now.
Also, prune out dead or diseased branches from shrubs or trees. Remember to prune at least 6-12 inches below the diseased area to make sure all of the diseased tissue is removed.
A common question asked by gardeners is whether diseased plants can be safely composted. The answer is most often, no. If your compost pile reaches temperatures in the range of 90 to 140 F, most of the disease organisms should be killed. (A temperature probe can be used to monitor compost pile temperatures.) If you are not sure if your compost pile is reaching these high temperatures, it is a good idea to discard the material by properly bagging it or by burning if this is allowed in your area.
This article originally appeared in the October 14, 1994 issue, p. 146.