M. Grabowski, UMN Extension Educator
By the end of the gardening season many plants are looking less than their best. At this point leaf spots, blights, fruit rots or other disease problems can easily be found in the yard and garden. An important piece of information about disease biology is that plant pathogens often survive from one season to the next in infected plant debris. As a result, a good garden clean up in the fall can reduce the number of pathogens that survive the winter and cause problems next year. Below are a few clean up strategies that can reduce disease in following growing seasons.
Trees and Shrubs
|Crabapple leaves infected with apple scab|
If leaf spot diseases are present, wait until leaf drop, mow leaves into the soil with a mulching lawn mower to speed up breakdown of infected plant material or rake up and remove all leaves from the site. Inspect branches for cracked or discolored bark that might indicate a branch canker or unusual tumor like growths known as galls. Flag these branches and mark your calendar to prune out diseased branches in February or March.
Perennial Flower Gardens
If leaf spot or blights are present, cut stems at the soil level and remove all infected plant material from the area. This is only necessary for diseased plants. Stems of healthy plants can be left until spring for winter interest and wildlife habitat.
For large gardens, bury all plant debris as soon as possible after harvest to begin the break down process. Do not plant the same family of plants at that same location for 2-4 years. Next year, plants of the same family need to be a minimum of 10 feet away from the location of this year’s diseased crop.
For small gardens, which do not have space to rotate to a new location, remove all infected plant debris including leaves, stems, roots and fruit.
Do not save seed from infected plants.
What to do with Diseased Plant Material
In Minnesota, it is illegal to put yard waste in with your household garbage. The good news is that the majority of plant pathogens will be killed in a compost pile that heats up. Unless you are an avid back yard composter and know your pile heats up, consider bringing diseased plant material to your city or county compost sites. If this is not available in your area, find a commercial composter (http://www.findacomposter.com/) that takes yard waste. Hot composting is the best way to dispose of green plant material like leaves, fruit and green stems.
Woody plant tissue can be chipped and composted, or burned. Check local regulations about burning in your area. Some yard waste drop off sites also accept woody plant material.
Clean up Tools and Equipment
Tools, trellis, stakes or other equipment used with diseased plant material can be cleaned with a 1 to 9 solution of bleach and water.
- Remove all soil and plant debris from tools and trellises.
- Mix 1 cup bleach with 9 cups water.
- Wearing water proof gloves wash all tools and equipment with the bleach solution.
- Rinse with clean water and dry before storing.