Virus diseases of green beans
Virus diseases of green beans is a problem in the open field. As viruses cannot move by themselves, they need a host or vector to hitch a ride. Two main methods of transportation or distribution are insects and humans. Insects are the most difficult to control and are also the most numerous, however, controlling human movement and hygiene can help reduce the spread of viruses throughout the field. Human control and hygiene should be the first step in disease management since it has very low cost. The problem is controlling insects. You might have a good pest control plan in place, but if the one insect came through your barriers, it can spread the virus in a section of the field. These infected plants then infect other insects feeding on them, so the virus spreads again. For that reason, virus control is so difficult and many seed companies are trying genetic methods for defence.
Bean mosaic virus
The margins and tips of leaves curl downwards. The leaves show typical yellow-green mosaic. Dark green bands along the veins contrast against light green parts of the leaf. Bean mosaic virus is seed borne. The only way to control the virus is to buy seed from reputable seed companies.
Yellow mosaic viruses
Symptoms are bright yellow spots between dark green coloured normal leaf tissue. Most of the leaves infected or malformed. This disease is a major problem and can cause significant crop losses.
The necrosis viruses cause dwarfing of plants. The whole plant becomes necrotic or brown and dries out and dies. It is a serious problem in some areas of production.