Mummy berry is one of the most destructive diseases affecting blueberries in North America. It is caused by the fungus Monilinia vaccinii-corymbosi, which infects both wild and cultivated blueberry plants. The disease is especially common in regions with cool, wet spring weather, where conditions favor fungal growth and spore spread. Growers can suffer major crop losses because the disease damages young shoots, flowers, and fruit, eventually turning healthy berries into hard, shriveled “mummies.”
The disease cycle begins in early spring when overwintered mummy berries lying on the ground produce small fungal structures called apothecia. These cup-shaped structures release spores into the air during wet conditions. Wind carries the spores to newly developing blueberry shoots and leaves, causing a primary infection known as “shoot strike.” Infected shoots suddenly wilt and bend over in a distinctive shape called a “shepherd’s crook.” Leaves may show brown discoloration along the veins before becoming dry and necrotic. As the infection advances, gray fungal spores may appear on leaf stalks and infected tissue.
A second phase of infection occurs during flowering. Spores produced on infected shoots are spread by rain, wind, and pollinating insects such as bees. These spores infect blueberry blossoms, leading to “flower strikes.” Northern highbush blueberry varieties are particularly vulnerable during bloom. Once flowers become infected, the developing berries gradually change color from cream to pink, then shrink and harden into tan or whitish mummified fruit. Inside each mummy is a corky fungal mass that allows the pathogen to survive winter. The mummies fall to the ground, where they remain dormant until the next spring, restarting the disease cycle.
Managing mummy berry requires a combination of cultural and chemical controls. Growers often rake, cultivate, or apply mulch beneath bushes to bury fallen mummies and reduce the number of spores released the following season. Good air circulation and proper pruning can also lower humidity within blueberry plantings. Fungicides remain an important management tool, especially during early shoot growth and flowering. Modern disease management programs recommend rotating fungicides with different active ingredients to reduce the risk of fungicide resistance and maintain long-term effectiveness.
Mummy Berry Disease in Blueberries
