Pea and Bean Weevil Mitigation
I'm working a new allotment plot this season and, as I normally do, I planted broad beans. I watched the little seedlings grow, but my glee quickly turned to concern when I noticed a curious problem develop. All the young leaves acquired these little notches along their edges. Below, you can see what I mean, like little peck marks, but they seemed too uniform and neat for pigeon damage... I felt puzzled. So, as I do, I commenced some research and RHS quickly offered the answer: pea and bean weevils ( Sitona lineatus). The leaf damage is caused by adult weevils. They overwinter in field margins and then fly in spring seeking out legumes, preferably beans and peas, on which to feed. Once fed, they lay their eggs in the soil around these same plants. Their larvae then feed on the plant's nitrogen fixing root nodules (housing rhizobia ). To quench your curiosity, you can see clusters of rhizobia filled root nodules growing on the broad bean roots below. My natural next question wa