Brown rot is a fungal infection that attacks stone fruit trees including peaches. Brown rot on a fruit tree can lead to severe infection, potential destruction of fruit crops and death of tree parts. Identify symptoms, damage and control methods for brown rot on peach trees for successful growth of vigorous plants and fruit.
Brown Rot Fungus
Brown rot on peach trees is caused by the fungus Monilinia fructicola. Every part of the peach tree is vulnerable to infection. The first signs to look for occur during wet weather; look for areas on flowers, fruit and twigs that display raised powder-like spots or brown-gray spots. These areas are covered with fungal spores responsible for brown rot disease. Infection occurs during the spring season, preferring wet plant surfaces that remain moist for a minimum of five hours, according to Cornell University. The ideal temperature range in conjunction with wetness is 60 to 70 F.
Fruit Rot Symptoms and Damage
Peach fruit affected by brown rot decomposes very quickly. Look for brown spots that become soft; these spots grow in size and the infected area becomes covered in spores that resemble powder. Brown rot attacks fruit in all stages of development. The fully rotted corpse of a peach fruit is referred to as a mummy and generally fails to fall from the tree, according to Cornell University.
Twig and Flower Rot Symptoms and Damage
Peach tree flowers that experience brown rot become completely brown in color. During the rotting process, blossoms wither and die. Whether or not rotten blossoms fall from the tree is important; some flowers drop after death while others remain on the tree and turn into a gum-like substance that releases fungi into twigs that, in turn, become diseased as well. Infected twigs display rotting areas of tissue called cankers. Infected twigs lead to leaf death and ultimately, the death of the twigs, according to Cornell University.
Resistance and Susceptibility
Depending on the peach tree variety, your peach tree may range from resistant to highly susceptible to brown rot. For successful growth and disease avoidance, choose among these resistant varieties: Babygold no. 5, Glohaven and Elberta. Peach tree varieties to avoid include those that are highly susceptible to brown rot and disease in general, and include, but are not limited to, Hale Harrison brilliant, Summercrest, Raritan rose and Maybelle, according to Cornell University.
For control of brown rot on peach trees, always follow sound maintenance by removing and destroying infected tree parts. When using pruning shears, always sanitize between each and every cut as well as from plant to plant as a method of disease transfer prevention. For chemical control, apply two fungicidal treatments. Use the first chemical application when the tree is in bloom from 20 to 40 percent. Apply the second treatment when flower bloom has reached 80 to 100 percent, according to the University of California IPM Online. Use propiconazole, fenbuconazole, thiophanate methyl or other fungicides labeled for control of brown rot on peach trees.