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Signs: White to gray powdery growth on the leaf surface. Symptoms shown on clematis leaves would be similar to those shown on this lilac leaf. Photo by Chad Behrendt |
Powdery mildew is a common fungal disease on clematis. |
Signs: White to gray powdery growth on the leaf surface. Symptoms shown on clematis leaves would be similar to those shown on this lilac leaf. Photo by Chad Behrendt |
| Causal organism: | Erysiphe polygoni |
| Over wintering: | In plant material and debris |
| Months of infection: | Growing Season |
| Method of dispersal: | Wind |
| Infection point: | Leaves |
| Control: | Sanitation (remove any fallen leaves) and properly water, fertilize, and mulch plants. Prune out dead or dying stems. Increase airflow and light penetration when possible to reduce humidity levels. Fungicides are not usually necessary. |
| Labelled fungicides: (First Application) |
Sulfur or thiophanate-methyl (Cleary's 3336) (at first sign of infection) |
| Comments: | Powdery mildew is most severe in early spring and late fall, and when environmental conditions consist of warm days and cool nights. |
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