Unfortunately, warm, wet weather conditions that are a necessity to cherry trees bring with it a higher incidence of fungal disease. One such disease, brown rot in cherries, attacks not only cherries but peaches, apricots, nectarines and plums as well. Brown rot cherry symptoms can increase exponentially in as little as 24 hours and decimate a crop. Read on for more cherry brown rot information including treating cherry brown rot.
Cherry Brown Rot Information
Brown rot on cherry trees is caused by the fungus Monilinia fructicola. As mentioned, the fungus spreads rapidly both during ripening and in storage post-harvest. Brown rot in cherries is fostered by warm, wet weather and under ideal conditions can occur within three hours of rainfall or irrigation. The longer the period of wet conditions, the shorter the incubation time, thus symptoms develop more rapidly.
Spores are produced first on early maturing cherries and then spread to late maturing trees and affect both edible and ornamental cultivars. Not only that, but during ripening, fruit is susceptible to insects and fruit cracking, leaving open wounds ideal for spore infection.
Brown rot on a cherry tree may also cause twig blight, which gradually weakens trees and makes them more vulnerable to other fungal infections and to winter injury.
Cherry Brown Rot Symptoms
At onset, the initial symptoms of brown rot in cherry trees are browning and death of blossoms. While blooms that are killed by brown rot stay attached to the branch with a sticky residue, those that are killed due to frost fall to the ground.
Twig blight, most common in apricots, may also afflict a tree with brown rot as the infection progress from the infected bloom to the spur and into the branch, resulting in a canker. These cankers are discolored and often covered with a sticky residue between the diseased and healthy portions of the branch. The cankers may girdle the entire branch as the disease progresses which cause the leaves to wilt and brown.
On fruit, the disease manifests as small, firm, brown lesions. The lesion grows rapidly until the entirety of the fruit is covered. Over time, the fruit dries and shrivels but stays attached to the tree even into the successive year.
All parts of the tree infected with brown rot become covered with tan to gray powdery spores, particularly when conditions are damp and temperatures are above 41 F. (5 C.).
Treating Cherry Brown Rot
Brown rot overwinters in mummified fruit, infected twigs and bark cankers. In the spring, the fungus begins to grow and produce spores that are then spread via rain or wind to blooms. When temps are cooler, the spores take longer to spread, but when temperatures are warmer, infection occurs and spreads rapidly.
Because the fungus lingers in fruit detritus, keeping the area surrounding the trees free from fallen fruit and other debris is of paramount importance. While the disease will not be eradicated, the number of spores produced will be lowered, which makes brown rot easier to control.
Remove not only any fallen fruit or plant debris, but in the spring, also remove any mummy fruit that remains on the tree. Also, remove any branches with cankers or twigs that have died from the disease when pruning in the winter.
If sanitation and pruning have had no effect on the severity of the disease, fungicides may be used. Fungicides must be applied twice, first when blossoms begin to open and then again 2-3 weeks before harvest. Do not apply the fungicide when fruit is still green. Wait until the fruit is ripening. Always read and follow the manufacturer’s instructions for fungicide application.