Brown Rot on Peaches
Searcy, Ark. –
Trees that bear fruit with a hard woody pit, or “stone,” are commonly called “stone fruit” trees. This group includes peaches, plums, apricots, nectarines, almonds, and cherries. Several serious fungal, bacterial, nematode, and viral diseases are common to stone fruits and should be of concern to all growers.
What is Brown Rot?
Brown rot is a highly destructive disease affecting all stone fruits. Caused by the fungus Monilinia fructicola, brown rot results in blossom blight, fruit rot, twig blight, and branch canker. Fruit rot is particularly common as fruit approaches maturity.
Recognizing Brown Rot
The first sign of infection is a small brown spot on the fruit, often starting at a wound caused by insect feeding or egg-laying. The rotted area expands rapidly, eventually developing tan-gray fungal tufts. These appear sooner on plums and cherries than on peaches.
Brown rot on peach fruits. a) noninfected fruit, b) infected fruit. Credit: D. Huff & A. Sarkhosh, UF/IFAS
Brown-rotted fruit usually retains its form, staying attached to the tree even after completely rotting and sometimes falling later. Whether they fall or remain in the tree, affected fruits become firm, black mummies that produce spores in the spring, initiating a new infection cycle.
When the fungus infects flowers or fruit, it can also spread to twigs, causing cankers or twig death. Infected twigs may develop gummosis (oozing sap), especially during rainy weather, and may even support fungal tufts.
Managing Brown Rot
Effective control of brown rot requires a combination of orchard management, proper spraying, and careful harvesting.
1. Sanitation and Orchard Management
Removing mummified fruits from trees and the ground and destroying them is crucial, though not sufficient alone. Proper pruning improves air circulation, promoting rapid drying of foliage and reducing the chance of twig punctures. Thinning crowded fruit also helps prevent infection by reducing contact between fruits. Later in the season, promptly removing damaged or infected fruit is important to prevent further spread to healthy fruit and branches.
2. Following a Fungicide Spray Schedule
Following a recommended fungicide spray schedule is the most effective control method. Commercial growers in Arkansas have several effective fungicide options; they can find recommendations here: Commercial Fungicide Guide. Unfortunately, options for homeowners are more limited: Home Garden Fungicide Guide.
3. Practicing Good Harvesting Techniques
Brown rot often causes more losses during shipping and at market than in the orchard. Wounds on fruit during harvest, even small ones, provide ideal sites for infection, as mature fruit is very susceptible. Following gentle harvesting practices minimizes wounding and the associated risk of rot.
By Sherri Sanders
County Extension Agent - Agriculture
The Cooperative Extension Service
U of A System Division of Agriculture
Media Contact: Sherri Sanders
County Extension Agent - Agriculture
U of A Division of Agriculture
Cooperative Extension Service
2400 Old Searcy Landing Road Searcy AR 72143
(501) 268-5394
ssanders@uada.edu