More Than One Cause

We see more than one thing going on for these bean plants. First, the yellow leaves with green veins tell us that there may be a nutrient deficiency problem. Sometimes this comes from the plant not having enough nitrogen and iron, but sometimes it happens because the pH is off. The first thing to do would be to have a pH test done of your soil. You can buy kits to do this or have it done by a local cooperative extension office or other soil testing lab. In the meantime, if you’re not opposed to a general liquid fertilizer use one according to directions. If you want to only use organic fertilizers try fish and seaweed emulsion.

Secondly, there is some leaf spot fungus – the most common cause of this is frequent splashing of the foliage with water. Be sure to water deeply less often (every 5 to 7 days using a soaker hose or sprinkler, not hand watering) instead of a little every day or every other day. Hand watering is never deep enough. Water in the AM so the leaves dry quickly and never spray the foliage with water in between your deep soakings. Pick off the black-sploched leaves and toss out – no fungicide necessary.

Thirdly – look under the leaves for signs of insect activity – the undersides might look dusty, dirty or kind of webby, but all very fine. It looks like there might be some sucking insects at work under the leaves such as lace bug, white fly, aphids or spider mites. You could spray the underside of the foliage with insecticidal soap for this. Do not use dish detergent because that can damage foliage – get an insecticidal soap from your garden center and use according to directions, making sure to spray under the leaves.