Nematode, Foliar

Foliar nematodes cause angular leaf blights bounded by the leaf's major veins, progressing from pale green to yellow and finally brown. New growth becomes curled, stunted, and twisted. Symptoms typically peak in mid to late summer and can be severe enough to defoliate parts of the plant. Secondary infections by Botrytis often compound the damage, creating additional gray mold on the damaged leaf tissue. The problem is most acute on oakleaf hydrangea and other susceptible ornamentals in the region.

These nematodes require a film of water to move across plant surfaces and enter through stomata or wounds, spreading rapidly when plants are spaced closely or overhead-irrigated. The life cycle completes in just two weeks under favorable conditions. Eliminate overhead watering entirely, and space plants to ensure good air circulation and rapid drying after any moisture. Remove and destroy infected leaves and plants promptly, as nematodes overwinter in buds and plant debris. Clean tools when moving between plants to avoid spreading the problem.