Mulberry trees are susceptible to infestation from various fungi, which in serious cases can result in the death of a tree. However, often growers can eliminate all traces of a fungus through the use of fungicides or other treatments.
Treating mildew-based fungi on mulberry trees
Mildew-based fungi commonly affect mulberry trees. The most widespread mulberry disease, powdery mildew, is caused by the fungi Phyllactinia corylea and Uncinula geniculata. Powdery mildew presents itself as a white powder-like substance on the lower leaves of the tree and can be treated by spraying trees with a fungicide. Powdery mildew thrives in dark, shady environments, so discourage it from forming by planting trees spaced well apart in areas that receive plenty of sunlight. False mildew, caused by the fungus Mycosphaerella mori, shows up as a cobweb-like coating on the leaves of mulberry trees. To eradicate this disease, spray trees with a fungicide at the first appearance of the fungus. Clear away fallen leaves to prevent reinfection.
Treatments for other mulberry tree fungi
Mulberry leaf spot, in which the leaves turn yellow with dark spots, is caused by the fungus Cercospora moricola. Fruitless mulberry trees are especially susceptible to this disease. Trees may be sprayed with fungicide, though trees will generally survive without treatment. To prevent reinfection, gather and remove all fallen leaves. Popcorn disease, which results from an infection of the fungus Ciboria carunculoides, gets its name from the popcorn-like appearance of infected mulberries. While popcorn disease will decimate the harvest of mulberry trees grown for their fruit, it's harmless on ornamental trees. To treat trees infected with this disease, pick and discard all infected berries, including all fallen fruit. Leaves that appear to be covered with a coating of rust are symptomatic of the aptly named leaf rust disease, caused by the fungi Aecidium mori and Cerotelium fici. This disease causes trees to shed leaves early, but will not otherwise harm the tree. If desired, spray the tree with fungicide, though the disease might also clear up on its own.
A more serious condition is cotton root rot, caused by the fungus Phymatotrichum omnivorum. This disease is characterized by yellow and wilted leaves. By the time this disease becomes visible on the leaves, the fungus has already spread throughout the root system, and the tree will probably die within a year. Avoid contracting this fungus by using fertilizers high in nitrogen. Bring in an arborist to look at mulberry trees infected with cotton root rot, as this disease can spread to the surrounding plants and trees.
Morgan Richter has a Bachelor of Fine Arts degree in screenwriting from the University of Southern California's School of Cinema-Television. Since 1999, she's written reviews and essays on pop culture topics for her personal website, "Preppies of the Apocalypse." Her novel, "Charlotte Dent", was a 2008 Semifinalist in the Amazon Breakthrough Novel Awards.