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The pea and bean weevil adults cause characteristic leaf notching around the leaf margins. The larvae can cause significant damage to the nitrogen-fixing root nodules. 

Damage

Leaf notching around the leaf margins caused by adult pea and bean weevil (Sitona lineatus) does not significantly affect yield. However, when adults are present they lay eggs leading to larvae. The damage to the nitrogen fixing root nodules by the larvae is serious and can reduce yield. Adults migrate in early spring from over-wintering sites (mainly grassy uncultivated edges of fields previously cropped with peas or beans) when temperatures start to warm.

Pheromone traps from Agralan can be used to monitor the pest. The procedure involves placing five traps on the headland of a field where a pea or bean crop has been previously grown. The threshold for crop treatment is an average of 30 weevils per trap per day.

Appearance 

Adult weevils are light grey-brown and are around 4-5mm in length. Their abdomen and thoraz are adorned in stripes. The larvae are white in colour with a brown-yellow head and are around 6mm in length. 

Control Recommendations 

There have been reports of poor performance of the pyrethroid insecticides currently used to control the pest and it is now known that the weevil has evolved resistance to them. The Processors and Growers Research Organisation (PGRO) commissioned research to test for pyrethroid resistance. Dr Steve Foster at Rothamsted Research found that there are populations of adult weevils that are resistant to a representative pyrethroid when it is applied at an equivalent dose to that used in the field. The next step is to establish the mechanism conferring this resistance which is likely to extend to other pyrethroids. In the meantime, growers should be aware that treatment with these compounds against this pest may not be effective. 

Fleece covering crops with the edges buried can provide an alternative control approach but needs to be in place before seedlings emerge and before the pest arrived. Extra fertiliser application may be required because the pest attacks the nitrogen fixing root nodules. Research into an entomopathogenic fungus for controlling the pea and bean weevil has started but there is not yet a commercial product.

Related links

 

Information from Rothamsted's Croprotect webpage supported by BBSRC NERC Sustainable Agriculture Research & Innovation Club

Related Organisations

Content below is from across the PEP community and is not necessarily endorsed by Stewards or by PEP

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Pests

Invertebrate pests cause problems in agriculture when the level of injury they cause reaches a point where the crop yield is significantly reduced.   

Beans

Field beans (vicia faba) are a widely grown break crop across the UK on around 170,000 ha. 

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Peas

Peas (pisum sativum) are grown either for combining dry seed (combining peas) or harvesting fresh as a vegetable or for freezing (vining peas).

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Pest Identification

This area is for identification of pest and beneficial insects and invertebrates.

Management of pea and bean weevils in peas and field beans

Pea and bean weevil (also called pea leaf weevil) is a particular risk to spring-sown peas and beans.

Pulse PEP
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