What is Mayhaw Brown Rot?
As mentioned, brown rot of mayhaw is a fungal disease cause by two fungi in the genus Monilinia, usually M. fructicola but less often, M. laxa. A healthy mayhaw with brown rot will undoubtedly survive, but it is still best to control the disease as soon as possible since if left unchecked, losses of up to 50% may occur. The fungi responsible for this disease are spread by the wind or on nearby plants that are also susceptible and infected. The spores may also be spread by insects that are attracted to the rotting fruit. Wounds opened up by insect feeding leave the fruit susceptible to contagion.
Symptoms of Brown Rot of Mayhaw
Luckily, brown rot in mayhaw trees is easy to identify and treat. The initial symptoms of brown rot usually occur as brown spots on spring blossoms. The infected blooms will eventually die off, often leaving behind a gooey film that adheres to twigs and opens them up to other infections and twig dieback. Healthy fruit may be produced from an uninfected tree only to become infected as it matures. Infected fruit becomes covered with brown rotting areas. As the disease progresses, the fruit actually dries up and shrivels creating what is known as “mummies.” Powdery, gray spores appear on both rotting fruit and mummies.
Mayhaw Brown Rot Control
Brown rot occurs during moist, warm spring months and can result in additional losses post-harvest if fruit is injured, bruised or stored at warm temps. It can overwinter in infected twigs and mummified fruit. Once fruit is affected, there is no recourse so, although not a lethal disease, it’s best to control at the first sign of infection. To manage twig infections, prune 4-6 inches (10-15 cm.) below the dead tissue. Then, if possible, burn the infected portions or bury them. Sanitize pruning shears between cuts in either a diluted bleach solution or in alcohol. To avoid infection in the future, remove and destroy any Prunus species on the property and dispose of any rotting or mummified fruit. Again, if possible, burn or deeply bury them. Prune the tree so that it has a vase shape which will allow for greater air and sunlight penetration, as this will then allow the foliage and fruit to dry more rapidly. Again, be sure to sanitize your pruning implements between cuts. Also, thin fruit so it doesn’t touch and allow transfer of the disease. Lastly, if you have had a history of brown rot in your landscape on other fruit trees, be sure to apply either a liquid concentrate or natural copper-based fungicide in the spring prior to any symptoms appearing. Be sure that the fungicide is approved for use on a mayhaw. Read and follow the manufacturer’s instructions regarding frequency and timing of the product.
