PGRO Crop Update (04.04.14)

Insect pests

Emergence of pea and bean weevils from over-wintering sites continues to be high and continuous due to the warm, dry weather. High levels of damage are being recorded in winter bean crops, and newly emerging spring bean and pea crops are at high risk.

Small seedlings are showing significant notching around the edges of leaves. Although crops should grow away from the foliar damage whilst weather stays mild, the adult weevils will lay eggs which are washed into the soil, hatching to allow larvae to feed on root nodules.

Sprays should be applied as soon as leaf-notching is seen. There are a number of pyrethroid products available for use in peas and beans for weevil control, and consideration should be given to products that will be used later in the season for bruchid beetle control, paying particular attention to maximum annual dose rates and number of applications allowed.

Field thrips infestations are also being reported and products used for weevil control will give good control of thrips.

Diseases - Field beans

Early-drilled crops of winter beans (end September to early October) are developing high levels of downy mildew. Although this disease can be found on both autumn and spring-drilled crops, autumn-sown crops do not usually develop severe symptoms and seldom require treatment, the disease being more damaging in spring beans.

However, conditions for downy mildew development have been favourable with cool humid weather prevailing, and early-drilled autumn crops may be more susceptible. If conditions become warm and dry following early infection, disease development stops and the plants are able to produce new healthy growth.

In cases where 25% or more plants are infected in winter or spring beans, sprays including the active ingredient metalaxyl-M will give good control of downy mildew. This level of infection is usually found at early flower stage but can be earlier when conditions are favourable.

Note that Folio Gold has been revoked for use in field beans. SL567A (metalaxyl-M) has Extension of Authorisation for Minor Use (EAMU) in field beans for downy mildew control and should be mixed with a partner fungicide. Wakil-XL (EAMU in field beans) seed treatment will control primary downy mildew infection.