Brown Rot Fungal Disease

Brown rot is a common fungal disease that affects stone fruits like peaches, plums, apricots, and cherries. It can be devastating to a fruit crop and can destroy most or all of the fruit on a tree in a relatively short period of time. Brown rot can infect the flowers, fruit, twigs, and branches. The symptoms can appear as blossom and twig blight, cankers on twigs and branches, and fruit rot.

To most home fruit growers, the progressive browning of the fruit is the most obvious symptom of this fungal disease and the most devastating. The rotting of the fruit on the tree can progress quite rapidly especially during cool, wet weather conditions.

Management of Brown Rot  

• Sanitation around the trees is one of the most important ways to try to reduce the incidence of this disease. Fungal spores overwinter in the mummified fruits that hang on the tree and fall on the ground. Spores can also infect the fruit from cankers on branches and infested foliage on the ground.
  
  • Remove all fruit mummies that are left hanging on the trees in the fall.
  • Carefully rake up all mummies and other plant debris from under the trees in the fall.  
  • In the early spring, prune out dead branches and twigs and branches with cankers.   
  • Thin the trees in the early spring to increase air circulation and allow more sunlight into the interior of the trees. This will reduce humidity and allow faster drying of foliage which can help prevent the development of the disease. This also allows better coverage of fungicides.  

• Treatment with fungicides is often necessary to prevent brown rot especially if the disease has infected your trees in the past. To be most effective, it is important to begin spraying for brown rot before infection occurs.   
  • Effective fungicides include copper fungicide, Captan, Immunox (not Immunox Plus), and sulfur fungicide. Many combination fruit tree sprays include both a fungicide and insecticide.
  • Begin a spray program when the flower buds begin to show color in the spring and continue spraying throughout the season according to the label directions.  
  • Alternate fungicides to increase effectiveness against other fungal diseases and to avoid pesticide resistance.
  • Always read and follow the label directions. When spraying fruit trees be sure the fungicide is listed for use on fruits and vegetables.