Leaf and Stem Blight (Alternaria tenuis)

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Importance- Usually of minor importance, Alternaria leaf blight can be severe on lower shaded leaves in dense plantings. The fungus also can infect unrooted softwood cuttings in nurseries.

Look For: Sooty, irregular-shaped spots and blotches, usually near leaf margins. Black stems and leaves of softwood cuttings.

Conidia

Biology- Alternaria overwinters on infected plant debris. The fungus, in addition to directly infecting leaves, also invades tissues wounded by various insects.

Control: Remove infected leaf debris to reduce inoculum and minimize disease. Apply a fungicide in nursery rooting beds if needed.
Diseased Leaves.	Shaded lower leaves colonized by Alternaria.