It is not possible to distinguish between the viruses based on symptoms alone. Many of these viruses are transmitted by aphids and are also transmitted through seed. For this reason it is unwise to save seeds from year to year. This disease is caused by the fungus Erysiphe polygonii . New growth appears contorted, curled or dwarfed and may turn yellow and drop.
Pods are dwarfed and distorted.
This is mostly a problem on fall beans. Powdery mildew is spread by wind and rain. On Southern peas, sulfur or fixed copper can be used. When the disease is first noticed, sprays or dusts of sulfur are recommended for use on snap and green beans only. Do not use sulfur on young plants.