Proper plant spacing can improve air drainage and rapid leaf drying. Control can also be achieved with the use of fungicide sprays applied as soon as symptoms are visible. Among the compounds registered for use in Connecticut are benomyl and thiophanate-methyl. Consult the label for dosage rates, safety precautions, and indoor use. Foliar nematodes, Aphelenchoides spp.
Patches can appear on the leaf and appear light or dark brown.
The disease is caused by microscopic worms called nematodes that tunnel in the leaf. Affected leaves should be cut off and discarded. Avoid splashing water from leaf to leaf. The nematodes can live as saprophytes in soil or potting mix for a short time so replanting the plant into fresh soil mix at the time the leaves are picked off can increase the control. When basil is grown indoors, irregular or ring-like pale tan spots appear on the upper side of the leaves.