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Fruit Tree Care: Organic Disease Control

It is possible to have an organic fruit tree orchard. Read about some of the most common fungal issues and how to practice organic disease control.

First and foremost, always plant top-quality, healthy nursery stock, and you'll be doing yourself a favor to also seek varieties that are naturally disease-resistant. You can most certainly avoid having to use synthetic chemical products and stick to either all-natural solutions or products that are certified organic. Preventing and controlling fungal diseases on your fruit trees is every bit as critical as feeding and watering, especially in locations that experience a cool, wet spring. It's always preferable to "prevent" than it is to "treat", and most fungicides are intended to be used before there’s a problem. Routine applications of effective products can save you time and money, as can diligently keeping a clean planting site by removing diseased fruit, branches, and fallen debris. Regardless of what you might find elsewhere, always read and follow all labels on the actual product you're using for application instructions and warnings prior to use. The following is intended to be used as a basic visual guide. Since many disease issues can look similar to one another, and proper identification is key to controlling any issue, we recommend that you contact your local county cooperative extension and provide photos (or samples at the request of the extension service) to assist in the identification, and eventually the treatment, process.

8 Common Fruit Tree Issues & Organic Disease Control

For reference in conjunction with cultural practices like routine care and maintenance of the trees and planting site. Sooty Blotch/Flyspeck Sooty Blotch on Apple Fruit Affects: apple trees, pear trees Description: Grayish-black soot-like splotches and/or tiny black specks. Sooty blotch usually shows up in late summer or fall, and is encouraged by normal temperature ranges combined with high humidity. Blotch and flyspeck are not rots; they appear only on the fruit’s surface. Treatment: Mix one ounce of bleach with one gallon of water and apply by soaking a rag in the solution and wiping the fruit. (Note: this may shorten the keeping ability of the fruit.) Alternatively, you can scrub the surface of the fruit using just water and a little elbow grease. It may not get the skin perfectly spotless, but it cleans off most of the sooty blotch and flyspeck chemical-free!

Bitter Rot

Bitter Rot on Cherry Fruit Affects: apple trees, pear trees, cherry trees Description: Not at all uncommon during hot, humid weather. Concentric rings of spores form on the fruit, leading to a foul-smelling rot. The V-shaped sunken spots usually penetrate to the fruit’s core. Treatment: Bonide® Copper Fungicide or a sulfur-based spray. Remove diseased fruit from branches and prune off any cankers found in tree limbs. Contact local county horticultural extension for further advice.

Black Rot

Black Rot on Apple Fruit Affects: apple trees, pear trees Description:  Black rot is a particular problem in the Southeastern states. Leaves will display a target-like leaf spot; as the season progresses, dark rot will become visible on the fruit bottom in rings, which eventually turn the fruit completely black. Treatment: Bonide® Copper Fungicide. Prune out dead wood and remove fallen debris under trees. Contact local county horticultural extension for further advice.


Apple Scab on Apple Fruit Affects: apple trees, peach trees Description:  Black, scab-like spots on both fruit and foliage. Cool, wet weather provide prime conditions for scab. If you spot scab, it must be treated throughout the season to prevent crop failure. Choosing a scab-resistant variety is the best prevention. Treatment: Bonide® Citrus, Fruit & Nut Orchard Spray, Serenade® Garden Disease Control (for Apple, Cherry, and Walnut trees) or sulfur spray. Rake and destroy fallen leaves to reduce the amount of disease that will carry over to the next year. Contact local county horticultural extension for further advice.

Brown Rot

Brown Rot on Stone Fruits Affects: apricot trees, cherry trees, peach trees, plum trees, nectarine trees Description: Brown rot infects stone fruit blossoms, stems and fruit. During summers with higher-than-average rainfall, young fruit that is damaged by insect chewing will develop this condition. Treatment: Bonide® Citrus, Fruit & Nut Orchard Spray or copper spray. Remove and/or prune infected tissues and areas on trees. Remove and discard any mummified fruit. Contact local county horticultural extension for further advice.


Gummosis on Cherry Tree Affects: peach trees, nectarine trees, plum trees Description: Gummosis causes lesions or "sores" with a thick, oozing orange gelatin-like resin on the trunk, limbs and/or twigs. Young branches may be killed if the condition is allowed to advance. Treatment: Prune away dead wood and water during dry spells to reduce stress on the tree. Contact local county horticultural extension for further advice.

Peach Leaf Curl

Peach Leaf Curl on Peach Leaves Affects: peach trees, nectarine trees Description: Peach leaf curl presents itself in cool weather, affecting the leaves and shoots of new leaves. Look for red spots about two weeks after leaves emerge, then white spores will appear. Leaves will yellow and fall off, and new leaves will emerge. This does not mean the tree is now healthy. For successful control, apply fungicide in early spring before bud swell and/or starting in the late fall after leaves have dropped. Applying fungicide after symptoms appear in leaves will not be effective. Treatment: Bonide® Copper Fungicide. Contact local county horticultural extension for further advice.

Cherry Leaf Spot

Leaf Spot on Cherry Leaves Affects: cherry trees Description: Sometimes called "shot hole". Yellow, irregular-shaped spots appear near the top of fruit with a light gray mold on the lower leaf surface. The disease will survive winter and reappear, so remove all leaves in the fall. The University of Nebraska recommends a fungicide treatment at petal fall, shuck fall and again two weeks later. Treatment: Bonide® Copper Fungicide or Serenade® Garden Disease Control (for Apple, Cherry, and Walnut trees). Contact local county horticultural extension for further advice.

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