How to Treat Blueberry Mummy Berry
Caused by the fungal pathogen Monilinia vaccinilicorymbosi, blueberry mummy berry is a relatively common but serious affliction of blueberry shrubs. In small plantings of blueberries, the disease may be manageable. However, in large commercial fields, blueberry mummy berry can be devastating to the whole crop. The symptoms generally appear early in the season as an overall browning around major leaf veins. As the disease progresses foliage, new shoots, buds, and blossoms may wilt, turn brown, and drop. New shoots may also curve back toward the plant like a hook. In spring, these symptoms can be mistaken for frost damage. When an infected blueberry shrub produces fruit, it may seem normal at first, but if immature fruit is cut open, it usually will have spongy, white, fungal flesh inside. As infected fruit ripens on the shrub, they will suddenly turn pink or gray and shrivel up into mummified blueberries. Eventually, the mummified blueberries will drop to the ground, where, if left, they will produce thousands of spores that will be carried on wind and rain the following spring to infect new plants.
What to Do for Mummy Berry of Blueberries
Proper sanitation is always key to controlling fungal outbreaks in the garden. If you have a blueberry bush with mummified fruit, be sure to prune infected branches back, pick up all debris around the plant, and destroy it with fire if possible. Sanitize pruners between plants to reduce the risk of spreading the disease to uninfected plant tissues. Throughout the growing season, inspect blueberry plants for symptoms of mummy berry to stay on top of pruning and sanitation. Mummified blueberries are small, black, and difficult to see, and a few may get missed. The fungus depends on this and overwinters in the fruit. In spring, warmer temperatures, rain, and increased sun trigger the fungi to produce spores. Heavy mulching in early spring or using a winter cover crop have been shown to inhibit spread of blueberry mummy berry by blocking out sun and preventing splash back. Preventative lime sulphur dormancy sprays or early spring soil sprays of urea are also effective treatments of blueberry mummy berry.
