Bean Leafroll Virus

Bean plants can be surprisingly prolific, and the fresh, crisp beans are a treat. Except sometimes things go wrong. Sometimes, bean plants turn yellow. It is normal to see lower, older leaves turn yellow and fall off. When entire plants start turning yellow, there's a problem.

Green beans (flockine) Pixabay

Bean leafroll virus (BLRV) goes by many other names: chickpea stunt virus, pea leafroll virus, legume yellows virus, and pea yellow top virus are just a few. Bean leafroll is a luteovirus infection spread by aphids. And this luteovirus attacks more than just peas and beans.

Once found only in peas and beans, bean leafroll has spread to include alfalfa, chickpeas, lentils, soybeans, and many other legumes. It can also occur in clover and vetch.

Chickpea plant infected with bean leafroll virus (Howard F. Schwartz, CSU, Bugwood.org) CC BY 3.0 US

Bean leafroll virus symptoms

Plants infected with bean leafroll turn yellow, and the leaves curl. This chlorosis occurs between the leaf veins. Stunting is common. These symptoms are similar to beet western yellows virus (BWYV) and nutrient stress. Symptoms can vary between species. In addition to these symptoms, these species-specific symptoms may occur:

• Fava beans—top yellowing, upward leaf curling
• Lentils—smaller leaves
• Peas—yellowing of leaf tips, downward leaf rolling

There can be a 50% to 90% reduction in pod production due to bean leafroll. In some cases, symptoms may appear and then fade away, creating a problem since the plant is still infected, and any aphids that feed on it can then spread the disease to neighboring legumes.

Bean leafroll virus management

The best way to reduce the chance of bean leafroll from occurring in your garden is to control aphids —easier said than done, I know. While you can dislodge aphids with a strong spray from your garden hose, not all plants take kindly to that treatment. Neem oil and insecticidal soaps are organic methods of aphid control.

Removing other host plants, such as burr medic and subterranean clover, can help reduce the spread of this disease. Since aphids and aphid eggs are brought into your landscape on other plants, putting new plants into quarantine is always a good idea.

There is no treatment for the bean leafroll virus. Remove infected plants and throw them in the garbage. Watch for resistant varieties being made available. They will have BLRV somewhere on the label. Finally, you can break this disease cycle by rotating your legumes with cereal crops, such as barley, corn, millet, or oats.