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HARDWOOD LEAF DISEASES OF MINOR IMPORTANCE
| Disease Agent | Injury | Control |
|---|---|---|
| Powdery mildew, caused by Microsphaera spp., Phyllactinia spp. and others. These fungi overwinter on dead leaves. Spores are windblown to healthy leaves. | A white, powdery mold occurs on leaves and buds. Leaves may be distorted, stunted and fall prematurely. | 2, 3 |
| Leaf blister, caused by Taphrina spp. This fungus overwinters on bud scales. When buds expand, infection of new leaves occurs. Spores produced on leaves are disseminated by wind. | Yellowish-green to purple blisters appear on leaves. Blistered leaves remain on the tree. | 1, 2, 3 |
| Leaf spots, caused by various fungi. Fungi overwinter in leaf tissue; spores are disseminated by wind and rain. | Small round to angular spots, variable in size and color appear on leaves. Defoliation may occur in extreme cases. | 1, 2, 3 |
| Nutrient deficiencies. These physiological conditions are soil related. Soil condition, such as pH, may make nutrients unavailable to plants, or the soil may be exhausted of some nutrients. | Leaf tissue turns yellow to brown; often this happens first along the veins. Some leaf fall may occur. Dieback may occur later if uncorrected. | 4 |
Controls for Urban Trees
- Rake and destroy
fallen, infected leaves.
- Maintain high
vigor through cultural practices.
- Control with chemical
fungicide.
- Control with appropriate fertilizer.
There are EPA registered chemicals for the control of these leaf diseases. Consult a specialist if the damage appears to be unusually severe and chemical control is needed.
USDA Forest Service - Forest Health Protection, Southern
Region
Last Modified: Friday, 11 January 2013 at 12:58:35 EST