Venturia shoot blight has been observed throughout northern Wisconsin this summer. Venturia shoot blight is one of the most common fungal diseases of aspen and is favored by cool, wet spring weather.
The pathogen rapidly kills expanding terminal and lateral shoots, causing shoots to wither and droop. It also causes leaf necrosis, appearing as black circles of varying sizes, necrotic curling at the margins, or complete leaf death. The disease is most damaging to seedling and sapling aspen, where it can reduce height growth and cause temporary stem crooking as lateral shoots are released and compete for apical dominance. Disease control is unnecessary in a forest setting.
Written by Paul Cigan, forest health specialist, Hayward (Paul.Cigan@Wisconsin.gov), 715-416-4920.