Ink Spot, Shot Hole (Ciborinia spp.)

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- Severe disease can reduce the photosynthetic capacity of leaves and cause premature defoliation. The disease is more severe on aspen and aspen hybrids than on the black poplars.

Look For: In early summer Tan to brown discolored areas with concentric white zones on upper leaf surfaces. Entire leaves may turn brown by midsummer. In midsummer Dark brown-black, raised, hard, oval structures (sclerotia) resembling "ink spots" scattered over the leaf surface. In midsummer to late summer "Shot holes" in leaves where sclerotia have fallen out.

Diseased Leaves

Biology- The fungus overwinters in leaf debris on the ground as sclerotia (masses of hyphae). During moist periods in late spring, fruit bodies (apothecia) develop; ascospores are forcibly discharged into the air and are carried to developing leaves. No further infection occurs until the following spring, when the cycle is repeated.

Control: Direct control is usually not necessary. Bury infected leaf debris and sclerotia in late fall or early spring to reduce inoculum levels in the immediate area and minimize new infections.

Sclerotia (Ink Spots)

For Additional Information: Ostry, M. E. 1980. How to identify ink spot of poplars. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 5 p.