Disease Spotlight Sooty mold
is the common name given to several genera of fungi that grow on honeydew secretions deposited on the plant by plant-sucking insects. Examples of insects that secrete honeydew include aphids, whiteflies, leafhoppers, mealy bugs, soft scales and psyllids. Although sooty molds do not cause an infection, they reduce the overall vigor and health of the plant by decreasing the amount of sunlight that penetrates the plant. They also reduce the curb appeal of the trees. Symptoms:
Grey to black mold and the presence of sap-sucking insects on all parts of the plant, including the fruit, stems, leaves and twigs. Ants may also be present as they use the honeydew as a food source. Heavily infested plants may be stunted, and leaves may prematurely senesce (age), die and drop. Management:
Management of sooty mold begins with managing the sap-sucking insect that is producing the honeydew. Information on managing sap-sucking insects on citrus can be found in the LSU AgCenter Insect Management Guide
. Depending on the type of insect, beneficial insects that feed on sap-suckers can be released. Ant management is also important for sooty mold management. Horticultural oils, neem oil or insecticidal soap can also be applied to suppress the problem insects. In severe sooty mold cases, use a strong stream of water or soap and water to wash off some of the sooty mold prior to applying insecticides or oils. Please send me an email if there is a fruit or nut tree disease you would like me to spotlight.