How to Troubleshoot Pole Beans With Yellow Leaves

Examine your plants if they develop yellow leaves. If they have irregular, mottled yellow spots on their leaves, the cause could be one of the bean mosaic viral diseases. The entire plant can turn yellow-green and few seedpods will form. No cure exists: the University of Illinois recommends planting varieties of pole beans that have been developed to resist this type of disease.

Rake all fallen leaves that your bean plants drop on the ground. The leaves provide a good environment for a disease known as bacterial bean blight to form. The symptoms of this disease include brown or yellow spots on the leaves and spots that look like water on the bean pods. Resistant varieties of pole beans are available and the University of Illinois also recommends not touching plants when they are wet.

Rotate your bean crop from place to place every year. If diseases are present in the soil they can spread to the new plants you grow the following summer.

Control the Mexican bean beetle's larva if you notice that your pole beans' leaves are covered with a yellow fuzzy-looking coating. This insect often occurs during early summer and can cause serious damage to bean plants. Hand pick both adults and larvae and drop them into a bucket of soapy water. If you introduce beneficial insects such as ladybugs, lacewings and minute pirate bugs, they will eat a good number of both adult and larval beetles. You may also spray your plants with insecticidal soap, making sure you cover both sides of all leaves.

Feed your pole beans with a high nitrogen fertilizer if older leaves begin to turn yellow and drop to the ground. This symptom can indicate a deficiency of this essential nutrient. If yellowing occurs between the veins of older leaves, a magnesium deficiency could be the cause.