|I am fairly sure that my yellow and green beans have mosaic disease. The leaves are mostly yellow and they haven't grown much. Assuming I should take them out, can I sow more of the same seeds in the same spot, and if so, do I need to treat the soil?|
|If your plants do have mosaic, it's a virus and is usually caused by infected seeds. Infected seeds will sprout and grow but the plants will show symptoms of the disease early in the season. Although it comes originally from infected seeds, once the disease is present in your garden, you shouldn't plant your beans in the same garden spot. Be sure you have the correct diagnosis before assuming that's the problem. The bean mosaic diseases cause plants to turn a yellowish green and produce few or no pods as you have described, but the leaves on infected plants are a mottled yellow and are usually irregularly shaped. The only satisfactory control for these diseases is to use mosaic-resistant bean varieties.
Bright yellow or brown spots on the leaves or water-soaked spots on the pods are signs of bacterial bean blight. Bacterial blight is best controlled by planting disease-free seed; avoiding contact with wet bean plants; and removing all bean debris from the garden at the end of the season.
After removing your diseased bean plants from the garden spread a few inches of compost over the soil and work it in. Plant something other than beans in that spot. Rotating crops is always a good idea from an insect and disease standpoint.