Honeysuckle leaf blight, caused by the fungus Insolibasidium deformans, is a common foliar disease of honeysuckle in Minnesota. This disease can infect most species and varieties of honeysuckle. The fungus survives winter in fallen leaves infected the previous year. In the spring, spores are rain splashed or wind blown to newly formed honeysuckle leaves. There they start new infections.

The first symptoms of honeysuckle leaf blight are crinkling and rolling of newly formed leaves. Within a few days the interveinal tissue turns yellow and brown. Brown lesions surrounded by yellow halos may be visible on some leaves. Infected leaves eventually turn brown and curl. Severely infected leaves drop prematurely. A white bloom of spores, produced during cool, humid weather, may develop on both leaf surfaces, but is generally heavier on the lower surface. These spores cause new infections on young leaves as they emerge. The disease will continue throughout the growing season if conducive weather is present.

Honeysuckle is seldom seriously injured in the home landscape. Cultural practices usually provide adequate control of the disease. Prune severely infected foliage during the growing season. Rake and remove fallen leaves in the fall. Prune dead or dying stems and selectively prune plants to increase air circulation. Water plants at the base early in the day to avoid prolonged wetting of the foliage. Under favorable conditions, cool temperatures (59º-64ºF) and high humidity, severe defoliation of the plant may occur. In severe cases, a spring application of mancozeb may be helpful.

P427H
Revised 12/99
Chad Behrendt, Crystal Floyd