CB2201 - CROP UPDATE 1 - 21st April 2022

Pea and Bean Weevil
Pea and bean weevils were recorded in traps in East Anglia and the East Midlands in late March and early April during warm weather. A monitoring system is available that detects adults as they migrate in early spring, consisting of five cone traps containing pheromone lures. It can be used to aid decision making in the following ways:

• Identifies seasons when weevil numbers are low and crops do not require treatment;
• Identifies time of peak activity and best timing of applications;
• Reduces the need for prophylactic spraying;
• May allow the selection of drilling time to avoid peak weevil activity;

Traps are sited on a grass margin or headland of a field that was cropped with peas or beans in the previous year and should be checked three times each week. A threshold is reached when an average of more than 30 weevils is recorded per trap on any one occasion. When a threshold is reached any crops that have just emerged or are likely to emerge within 10 days are likely to be at risk. Insecticides should be applied at first signs of crop damage, seen as u-shaped notching on leaf edges, especially where there is a history of severe damage. A second spray may be required if crops are growing slowly. If a threshold is not reached or occurs more than 10 days before crop emergence, insecticides are not required. Winter beans seldom require treatment as they are well established before attack occurs.
Traps are available from Koppert UK https://www.koppert.co.uk/pea-and-bean-weevil-trap/

Pea Moth
Pea moth traps should be ordered in time for the coming season. Pea moth activity can start at the beginning to middle of May and pea moth is one of the most damaging pea pests in the UK. The caterpillars (larvae) feed on peas within the pod causing damage to quality. Spraying should be related to the development of the insect rather than to the stage of growth of the crop. Therefore, insecticides should be applied while the larvae are exposed, from the time of hatching to the time of entering the pods. The timing of application is critical for optimum control. Since pea moth can be a localised problem, overall spraying of peas over a wide area on any one date is not advisable as local conditions influence the behaviour of the pest. A system of accurately timing the application of insecticides is commercially available in the form of pheromone traps and a spray prediction tool. The traps attract male moths when placed in peas, and by monitoring the catches in the trap, growers can decide whether there is a need to spray, and time any necessary applications efficiently.

Pea moth monitoring systems are available from the following suppliers:

Koppert UK Ltd. www.koppert.co.uk
Dragonfli Ltd. Tel: 01376 563322.
www.dragonfli.co.uk

Andermatt UK. Tel: 07939 395059.
Email: contact@andermattuk.com
www.andermattuk.com?

Traps are received in sets of one or two, depending on the supplier. One set is required for each block of peas, for example, a farm having all the pea fields within a restricted area need only purchase one set of traps, but in fields of 50 ha or more two sets are required. Traps must be placed in the pea crop by the middle of May and examined at two-day intervals. The number of moths caught by each of them is noted on each occasion.

The threshold for combining peas, which determines whether treatment is necessary, is ten or more moths caught in a trap on two consecutive occasions. Timing of sprays must be related to egg development, and this is affected by temperature. A spray date can be obtained from the PGRO website - https://www.pgro.org/pea-moth/ based on a computer prediction, 3 - 4 days after reaching a threshold. On the predicted spray date, crops which are at the first pod set stage, or which have flowered should be sprayed, but later crops should only be sprayed when they reach first pod set. Crops with flat pods are susceptible to damage. A second application should be applied 10-14 days later.

In vining peas, where the acceptable level of damage is much lower, the threshold for combining peas is not suitable and therefore the traps should only be used as a guide as to the presence of moths. In areas where damage has been a problem in the past, crops which are at the first pod set stage should be treated with a single application. Take care to observe the minimum interval between application and harvest.