Pulse Crop Bulletin - 12th July 2012

Becky Ward, PGRO principal technical officer, comments on Bruchid beetle control in beans, and on pests and diseases in peas.

Beans

Bruchid beetle control

Spring bean crops remain susceptible to damage whilst still flowering. Most spring bean crops will have had the first insecticide application to control the pest. Second sprays should be applied 7 to 10 days after the first.

Black bean aphid

Black bean aphid colonies are present in crops and are relatively easy to control using aphicides. Spring beans may still be flowering and the choice of aphicides is limited to those which will not harm pollinating insects. Colonies first develop on headlands but, where a general infestation of 10% of plants are colonised, spraying should be carried out as soon as possible.

Peas

There is potential for extended flowering and late pod set in peas. It is possible that additional applications for pea moth and disease control may be necessary, as well as an additional application of manganese to prevent marsh spot.

Pea moth and aphid

Pea moths continue to be active and new thresholds have now been reached in many areas. For specific information on spray dates for your area call the PGRO pea moth telephone service on 01780 783099.

In combining peas, control is best achieved by a two spray programme, and the second spray should be applied 10 to 14 days after the first. This application may coincide with an aphid spray, and half rate aphicides may be sufficient when combined with full rates of contact acting pyrethroids for moth control.

Pea diseases

Rainfall and high humidity favour leaf and pod spot infection. Treatment at this stage will give protection, and there are a number of approved fungicides. Cyproconazole plus chlorothalonil will help to protect against powdery mildew, which can be a problem in late maturing varieties.

In vining peas, rainfall and warm temperatures increase the risk of sclerotinia. Treatment to protect against botrytis and sclerotinia should be made to susceptible crops as they reach the first pod stage. Check with processors before treating.

Manganese

High rainfall can reduce availability of manganese and encourage extended flowering and pod set. Three applications may be necessary to prevent marsh spot. Ensure 5 kg/ha manganese sulphate or an equivalent dose rate of formulated manganese at each application.