Mulberry Tree Pests & Diseases From Humidity

Black mulberries attached to the mulberry tree

The mulberry tree is a common tree in North America, Europe and Asia that is from the genus Morus and has edible fruit that resembles the blackberry. There are three different types of mulberry trees: white mulberry, red mulberry and the black mulberry. The three mulberry tree varieties thrive in warm climates, but are susceptible to a variety of pests and diseases that thrive in the same climate.

Popcorn Disease

Popcorn disease of the mulberry tree makes the fruit produced on the tree swell up, resembling popcorn grains. According to the Oklahoma State University website, the disease is caused by the fungus Ciboria carunculoides. The fungus infects the ovaries of the fruit, thus causing the fungus to attach to the growing fruit later in the season. The fungus thrives in humid climates and is a common disease for the mulberry tree; however, the disease does not cause damage to the tree and is only a serious problem for mulberry fruit harvesters. The fungus infects the fruit for multiple seasons, therefore it is important to remove the infected fruit and burn it before the fruit falls to the ground to reduce further infection.

Cotton Root Rot

Cotton root rot is a serious disease for mulberry trees that cause sudden wilt and death during humid summer months. According to the University of Arizona Department of Plant Pathology website, the soil-borne fungus Phymatotrichopsis omnivora causes cotton root rot. Symptoms include rapid wilt and death of the infected mulberry tree, rotted roots and dead and dying leaves remaining attached to the tree. Cotton rot thrives in humid climates and spreads quickly in the soil; however, cotton rot can survive in cool temperatures, but does not reproduce as quickly.

Sooty Canker Disease

Sooty canker disease is a fungus-borne pathogen that affects mulberry trees in humid climates. Sooty canker disease, caused by the fungus Hendersonula toruloidea, infects tree wounds and cracks in humid climates with temperatures ranging from 91 to 97 degrees F. Symptoms of sooty canker disease include wilted leaves, bark peel, a black mass of spores in infected areas, cankers and dieback in tree branches.

Treating Cotton Root Rot

Cotton root rot is a hard disease to control, as it is hard to spot early symptoms and has no treatment options once infection occurs. According to the University of Arizona College of Agriculture & Life Sciences website, treatment of cotton root rot consists of having an experienced professional identify the disease, and doing a crop rotation of non-susceptible trees. Identification is important because cotton root rot shares many of the same characteristics of other fungal-related root rot diseases.

Treating Sooty Canker Disease

According to the University of Arizona Department of Plant Pathology website, the disease is best controlled by reducing pruning and cleaning pruning tools with 20 percent bleach solution. Tree sunburn is a common way that sooty canker infects trees, therefore, it is important to reduce pruning of branches that provide shade. Prune infected areas, dispose of the pruned branches, and use a fungicide to prevent further infection.

References

• Oklahoma State University: Popcorn Disease of Mulberry
• University of Arizona: Cotton Root Rot
• University of Arizona: Sooty Canker