Archive:Poplar/Leaf and Stem Blight

From Bugwoodwiki

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.