Mould on beans – A solution to common bean plant diseases

Do you have mold on your bean plants? Some common bean plant diseases can lead to the development of white mould on bean plants. Do not despair. Read on to find out what to do about mouldy bean plants.

Help, there’s white mould on my bean plants!

The grey or white mould on the beans is an indicator of a fungal or bacterial infection . Dusty or hairy mold (usually only found on lima beans) is caused by fungal spores that germinate on dry foliage when humidity is high. Particularly common in late summer and fall, these late blight diseases do not usually kill the plants, but they do stress them, which can result in reduced yields.
To reduce the possibility of dusty or woolly mould , avoid water stress , prune infected leaves and pods and keep the garden free of plant litter. Also make sure to rotate the bean crop annually.
Mildew on the foliage, stems or pods of beans, accompanied by successive rots, is an indicator of mycelium , another fungus that is abundant in hot weather. This fungus, however, enjoys the accompaniment of water-soaked leaves. To avoid this fungal disease, rotate crops again and clean up plant remains, keep the surrounding area free of weeds and increase the space between bean plants to increase air circulation .
Another common disease of bean plants is bacterial wilt , which coagulates the circulatory system of the plant. This disease is spread by the cucumber beetle under moist conditions. Signs of bacterial wilt are leaf drop at first, followed by wilting of the entire plant. The presence of the disease can be specifically diagnosed by cutting a stem near the crown and observing the sap; it will be milky, sticky and slimy. Once the plant is infected, there is no way to stop the disease. Remove and destroy infected plants as soon as you recognize symptoms.
Finally, Sclerotinia sclerotiorum may be the culprit in mouldy bean plants. White mould usually begins when the plants wilt after flowering. Lesions develop rapidly on infected leaves, stems, branches and pods, which are eventually covered with white fungal growth. White mould is prolific under conditions of high humidity, accompanied by moist foliage and plant soil, usually at the end of the growing season.
As for the previous diseases, remove any infected part of the plant or the whole plant if it appears to be severely infected . Water moderately, just enough to avoid stress to the plant, but allow the soil to dry out between waterings. Space the bean rows further apart to allow air circulation, rotate crops, and as always keep the rows free of weeds and debris.
Applications to fungi can help control white mold on beans. Follow the manufacturer’s instructions for timing, rate and method of application.