Phytophthora capsici & Pythium species
Figure 1 - Phytophthora blight symptoms first appear aslarge water-soaked lesions on the leaves. Leaves die and fall off the plant. Brown stem lesions and white powdery areas on stems are characteristic. Pods show white mycelial growth.
Figure 2 - Pods infected with P. capsici shrivel and become dry and leathery.
Figure 3 - Pythium species may infect planted seeds prior to germination, germinating seedlings, young plants, or older plants during flowering and pod stages. Symptoms appear as water-soaked areas on the hypocotyls and main root system which may extend above ground.
Figure 4 - The water soaked area eventually dries out, becomes somewhat sunken, tan to brown in color, and plants then wilt and die.
Figure 5 - Pods in contact with soil may become infected by Pythium, exhibiting water-soaking and fluffy white fungal growth (cottony leak).
- Infested soil, equipment and irrigation water
- Wet, compacted soils
- Susceptible bean varieties
- Previous cropping history of squash, pumpkins, cucumbers, melons or peppers; disposal of culled cucurbits in a clean field
- Frequent high rainfall and warm temperatures greater than 25oC (77oF) favor postemergence wilts and pod rots; and Pythium damping off is generally favored by lower temperatures.
- http://www.apsnet.org/ - Compendium of Bean Diseases, 2nd Ed.
Courtesy of H.R. Dillard, S. L. Rideout and H. F. Schwartz (Colorado State University) (03/2011)