🐛✗ Tested and false“U-shaped notches chewed around the leaf edges mean the pea or bean plant is losing a serious chunk of its yield.”
The notching looks alarming because it spreads across almost every leaf, but the actual leaf area lost is generally small even on heavily marked foliage, and established plants tolerate the feeding well. The exception is a small seedling, where the same amount of chewing costs proportionally more and can genuinely check its growth.
Our read Extent of visible notching is a poor guide to harm once a plant is past the seedling stage. Growth stage, not notch count, is the thing worth checking.
What to do: On an established plant, leave notched foliage alone. On a seedling, check how much of each leaf is affected and keep it watered so it grows through the vulnerable stage quickly.
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- RHSLeaf area lost is generally small and established pea and broad bean plants can tolerate the feeding, with only small seedlings at risk of a growth check.
“If you spot weevil notching on peas or broad beans, you should reach for an insecticide to protect the crop.”
No chemical control is given for this pest in a garden setting; guidance goes straight to fleece, watering and simply tolerating the damage on established plants instead. That reflects a domestic-scale pest that established plants shrug off, so spraying is treating a cosmetic symptom that was never going to cost the crop anything.
What to do: Skip the spray. Cover seedlings with fleece or cloches during their vulnerable stage and keep them watered; leave established plants to carry on regardless of how notched the leaves look.
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- RHSNo chemical control is recommended; management is usually unnecessary since plants can generally tolerate the damage.
“The visible leaf notching is where this pest actually does its damage, so that is what to watch for.”
Garden and field guidance point at two different culprits. The RHS frames the adult notching as the visible but largely cosmetic damage, with garden-scale plants coping fine either way. AHDB's guidance for commercial pea and field bean growers instead identifies larval feeding on the root nodules underground, invisible from the surface, as the main driver of any real yield loss, with the notching itself serving mainly as an early warning sign that adults and their eggs are present.
Our read The disagreement is really about scale, not a genuine contradiction. AHDB is describing crop-loss economics on field-scale sowings; RHS is describing what a garden or allotment plant experiences, where that same larval feeding usually doesn't add up to a growth problem. Both can be right for their own context.
What to do: In a garden bed, judge the plant by its growth, not the leaf notching. If seedlings are struggling despite watering, the underground root-nodule feeding is a more likely explanation than the notches themselves.
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- RHSLarvae feed on nitrogen-fixing root nodules but do not usually affect plant growth in gardens and allotments.
- AHDBLarval feeding on root nodules is the main cause of yield loss, while adult feeding causes the visible notching around leaf margins.
“Once pea and bean plants are past the seedling stage, this pest can be ignored completely.”
This is one of the few pest claims that holds up cleanly at garden scale. Established pea and broad bean plants tolerate the adult feeding, and the larvae feeding on root nodules underground do not usually affect plant growth in gardens and allotments either. The seedling stage is the one point genuinely worth a closer look; past it, there is nothing further to monitor for.
What to do: Watch closely only while plants are small. Once they are established and growing away, there is no need to keep checking leaves for notching.
In Scotland: A slower Scottish spring stretches the seedling stage out over more weeks, so it is worth confirming plants have actually reached that established, tolerant size before writing this pest off, rather than assuming it from the calendar date alone.
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- RHSEstablished pea and broad bean plants can tolerate the feeding, and larvae feeding on root nodules do not usually affect plant growth in gardens and allotments.
