Abstract

SHURTLEFF, MALCOLM C. 1989. Diagnosing shrub diseases. Grounds Maintenance 24(7): 18, 22, 26.

Correct diagnosis is the first and most important step in the treatment of any disease. Base your disease control programs for shrubs on a thorough knowledge of the diseases that are likely to appear in your area, the plants that are susceptible to attack and an early and accurate diagnosis of the problem. You must start control measures before or at the early onset of the disease, but preferably before symptoms appear. First examine the leaves, and then progress to the young shoots, branches and main stem(s). Finally, check the crown and roots. Leaves are the best indicators of shrub health. By inspecting them, you can tell whether the plant is vigorous or declining. Wilting is due to a temporary or permanent deficiency of water in the leaves, shoots or fruit. Girdling cankers are usually oval or elongated with discolored wood beneath the bark. Galls in twigs, branches, main stem or crown may be caused by a number of factors, including insects, bacteria and fungi. Severely cold weather or sharply fluctuating winter temperatures may kill individual twigs, branches or entire shurbs. Root problems are usually difficult to diagnose. Many times the culprit is two or more factors working together.

• © 1990, International Society of Arboriculture. All rights reserved.