Health Protection, Southern Region
HARDWOOD LEAF DISEASES OF MINOR IMPORTANCE
|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.
|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.
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.
Leaf blister on oak.
(Click for detail. JPG 24K).
(Click for detail. JPG 38K)