The fungus originated in Japan and was introduced to the Boston area via infected gypsy moth larvae in 1910. The fungus was never recovered, despite attempts in subsequent years, and so it was thought not to have established. This fungus grows best in warm, humid weather. Carbaryl, malathion, methoxychlor and Bacillus thuringiensis var. Consult the labels for dosage rates and safety precautions.
Mites often infest chestnut leaves, causing a rusty brown appearance.
Mites can be controlled by spraying with insecticidal soap or ultrafine horticultural oil, which are among the compounds registered for use against this pest in Connecticut. The predatory mite, Neoseiulus fallacis , is most commonly found feeding where there are mite infestations. Special care should be taken with soap or oil to obtain thorough spray coverage, because they only work on contact. Consult the label for dosage rates and safety precautions. Avoid applying carbaryl or pyrethroids, which tend to be much more toxic to the predators than to the pest spider mites.