Disease Prevention

Cherry Brown Rot: A Damaging Disease for Cherry Trees

Cherry brown rot is a common and destructive fungal disease that affects cherry trees, as well as other stone fruits like peaches, plums, apricots, and almonds. Caused by the fungus Monilinia fructicola, brown rot can spread rapidly during warm, wet weather conditions, leading to significant crop losses.

How Does Cherry Brown Rot Spread?

The fungus that causes brown rot overwinters in fallen or mummified fruit, as well as in other infected plant material. In the spring, when temperatures rise and moisture is abundant, the fungus becomes active and produces spores that are carried by wind and rain to developing flowers and young fruit.

The longer the period of wet conditions, the shorter the incubation time for brown rot, and symptoms can develop rapidly. Spores are first produced on early-maturing cherries and then spread to late-maturing trees, affecting both edible and ornamental varieties.

Symptoms of Cherry Brown Rot

The initial symptoms of cherry brown rot are browning and death of blossoms. Infected blossoms may remain attached to the branch with a sticky residue, while those killed by frost typically fall to the ground.

On fruit, the disease manifests as small, firm, brown lesions that rapidly expand until the entire fruit is covered. Over time, the fruit dries and shrivels but remains attached to the tree.

Other symptoms of brown rot include:

• Twig blight, which can weaken trees and make them more vulnerable to other infections and winter injury
• Cankers, which are discolored and sticky lesions that can girdle branches and cause leaves to wilt and brown
• Powdery gray spores on infected plant parts, especially in damp conditions

How to Prevent Cherry Brown Rot

The best way to prevent cherry brown rot is to use resistant cultivars. If you already have a cherry tree, there are several steps you can take to reduce the risk of infection:

• Remove mummies and fallen fruit: Regularly remove any mummified or fallen fruit from around the tree to eliminate potential sources of infection.
• Prune infected plant material: Prune off any branches or twigs that show signs of brown rot, including cankers and dead or dying tissue.
• Create an open canopy: Prune the tree to create an open canopy that allows for good air circulation, which helps to dry out the leaves and reduce the risk of fungal infections.
• Water from under the leaves: Avoid watering the tree from above, as this can splash spores onto the leaves and fruit, increasing the risk of infection.
• Keep the area clean: Remove any debris, such as fallen leaves and weeds, from around the tree to reduce the number of potential hiding places for the fungus.

Treating Cherry Brown Rot

If sanitation and pruning measures have not been effective in controlling brown rot, fungicides may be used. Copper fungicides can provide some benefit, but they may not be sufficient in all cases.

Organic control methods include products containing pyrethrins and sulfur.

Always read and follow the manufacturer’s instructions carefully when using any fungicides.

Conclusion

Cherry brown rot is a serious disease that can significantly impact cherry production. By understanding the disease cycle, symptoms, and prevention and treatment methods, you can help protect your cherry trees and ensure a healthy harvest.