Disease: Brown RotPathogen: Monilinia fructicolaHost: Stone fruits, Prunus spp.
In addition to apples, peaches and plums are popular backyard trees for homeowners who wish to grow their own fruit. When peaches and plums are harvested, homeowners may notice blemishes and blotches on their fruits. Brown rot is one of the most important, if not the most important, disease of stone fruits such as peaches, plums, cherries, apricots and almonds worldwide. It is caused by the fungus Monilinia fructicola. Symptoms and signs of brown rot are shown in the figure and include the brown fuzzy growth of the fungus on the fruit surface and the rotting of the fruit beneath it. This rotting can occur on the tree, in storage, and on the kitchen shelf.
The fungus has two spore stages, one forming in the spring on the mummified fruit beneath the trees. This spore stage allows the fungus to establish new infections in flowers in the spring. The second spore stage infects flowers, twigs, and fruit. It is this second stage that is most commonly seen and which causes fruit rot.
The disease is managed in several ways. First, some resistant cultivars are available. Second, fungicides are effective in reducing damage when applied several times at the flowering stages. Third, infection of isolated individual trees can also be reduced by pruning infected twigs and removing mummified fruit hanging in the trees and from beneath the tree.