By Frank M. Watson
UGA Extension
Good sanitation in the garden this fall will reduce disease problems next spring. Many disease-causing organisms can survive the winter in diseased plant debris. Reducing or eliminating these potential overwintering sites for pathogenic fungi, bacteria, nematodes and viruses will cut down on the occurrence of disease problems the following season.
If a compost pile reaches temperatures in the range of 110 to 160 degrees Fahrenheit, most disease-causing organisms should be killed. If you are not sure if your compost pile reaches these high temperatures, it is best to discard diseased material.
Many common foliar diseases can be partially controlled through good sanitation. Iris leaf spot, black spot on rose, tomato early blight, Cercospora leaf spot of ligustrum, and apple and crabapple scab are just a few examples. If leaf spot problems were a garden problem this year, remove and throw away plant debris and fallen leaves this fall.
Removing crop debris from the garden prevents the overwintering of vegetable pathogens and insect pests. Many pathogens can survive the winter in plant debris, culled fruit or plant stubble left in the garden. Removing or plowing under crop stubble helps to destroy overwintering populations of pathogens.
Equipment such as trowels and shovels that have been used in diseased areas of gardens and landscapes should be cleaned thoroughly before being used again.
Also, prune out dead or diseased branches from shrubs or trees. Remember to prune at least 6 inches below the diseased area to make sure all diseased tissue is removed. Disinfect pruners in rubbing alcohol or a 10 percent bleach solution between cuts, and oil pruners when finished to prevent rust. Severe or renewal-type pruning should be postponed until February or March.
A common question asked by home gardeners is whether pathogens on diseased plants can be destroyed through composting. The answer most often is “no.” If a compost pile reaches temperatures in the range of 110 to 160 degrees Fahrenheit, however, most of the disease-causing organisms should be killed.
A temperature probe can be used to monitor compost pile temperatures. If you are not sure if your compost pile reaches these high temperatures, it is best to discard diseased material by bagging and throwing it away or by burning if allowed. Simply maintaining a debris pile in the back of the yard will not effectively destroy plant pathogens.