Backyard fruit growers are often confronted with diseases that can limit the health and yields of their crops. Although use of resistant cultivars and supplementary fungicide sprays are helpful for disease management, sanitation is also needed. To achieve optimum fruit disease control, sanitary practices are essential. The main effect of sanitation in the orchard or garden is to eliminate or reduce the amount of the pathogen or causal agent of the disease.
Many disease-causing fungi and bacteria survive on twig and branch cankers, mummified fruit, and leaves on the ground. Managing the pathogen is accomplished by cultural practices such as pruning out and destroying diseased and dying twigs and branches, by raking up and destroying fruit mummies and infected fallen leaves, or by removing diseased and dying plants.
In some cases, sanitation involves removing and destroying an alternate host plant which harbors the disease. The classic example is the removal of red cedars and other susceptible junipers from areas near the orchard to stop the dissemination of cedar-apple and cedar-quince rust to apples. Whether eliminating an alternate host or cleaning up a fruit planting, growers who make the effort to learn how pathogens are surviving will be more successful in their disease management efforts.
An added benefit of using pruning for sanitation is that pruning or thinning out diseased stems or branches also allows free air circulation and improved sunlight penetration to reduce the wetness and humidity in the fruit crop. This reduction in the moist conditions needed for infection by fungi and bacteria will reduce the amount of disease that develops.
The dormant season is a good time for sanitation efforts. The following are some selected fruit diseases with specific sanitation procedures useful in disease control.
Apple scab. The fungus overwinters on old leaves on the ground. Destroy all of last year’s leaves by raking them up and destroying them.
Apple fruit diseases. Fruit rot pathogens can be found on dried, shriveled fruits, called mummies. Most of the pathogens are also capable of residing in dead twigs and branches in the tree. Remove fruit mummies from the tree and destroy them and prune out and destroy dead wood and cankers.
Apple and pear fire blight. The bacteria survive in branch and limb cankers in the tree. The dead wood associated with the cankers also harbors fruit rot fungi. Prune out and destroy fire blight cankers.
Peach and plum brown rot. The decay fungus survives in mummified fruit. They should be removed and destroyed.
Peach and plum cankers. The fungi survive in dead and cankered twigs and branches. Prune out and destroy cankers and dead wood.
Plum and cherry black knot. The fungus survives in the swellings. Remove and destroy all knots before bud break. Prune a few inches below the swelling.
Cherry leaf spot. Rake up and destroy last year’s fallen leaves because they harbor the fungus.
Grape black rot. The fungus lives in tiny, dried, shriveled fruit and in cane cankers. Pick off and destroy mummies still hanging on the vine and prune out and destroy diseased canes.
Raspberry and blackberry anthracnose and cane cankers. Canker fungi reside in diseased stems of brambles. Remove and destroy diseased and winter-injured canes.
Strawberry gray mold. The gray mold fungus colonizes and produces spores on dead leaves and petioles. If feasible, hand pick and destroy dead strawberry plant tissue.
If fungicide sprays are needed to supplement these sanitary practices, spray guides are available from the Christian County Extension office.
Got gardening questions? I’ll be hosting a weekly Zoom meeting called “Garden Q&A Live”, Thursdays from 12:00 to 1:00pm. Feel free to pop in and ask gardening questions or discuss what’s going in your garden during the week. For details visit: www.ChristianCountyHorticulture.com
— Kelly Jackson, Christian County Extension Agent
