Figures 1a and 1b – Angular leaf spot lesions are most characteristic on leaves, and appear as gray or brown irregular spots that may be bordered by a chlorotic halo. Lesions become necrotic and assume the angular shape characteristic of the disease. Black synnemata and conidia are produced in lesions on the lower surface of leaves (and other infected plant parts). Symptoms should not to be confused with Nematode Angular Leaf Spot which does not produce any fungal structures in lesions.
Figure 2 – Dark brown elongate lesions may develop on petioles and stems of infected plants.
Figure 3 – Pod lesions are large, oval to circular, reddish brown spots, usually surrounded by a darker-colored border (Fig 3); in contrast to other types of infection (e.g., common bacterial blight water-soaked lesions).
- Infected seed, infested debris and volunteers from previous seasons
- Rainstorms, high humidity and sprinkler irrigation
- Moderate temperatures with daily highs less than 28°C [82°F]
- Compendium of Bean Diseases, 2nd ed.
Courtesy of H. F. Schwartz & Forestry Images (02/2011)