Becky Ward, PGRO principal technical officer, comments on winter bean crops, pea and bean weevil, field thrips, and herbicides ...
Winter bean crops
Frost damage has been reported in some crops of winter beans and may predispose the plants to disease infection. Plants should recover as conditions improve and there is no need to apply fungicides at this early crop growth stage. If conditions become wet and chocolate spot becomes apparent, protectant fungicide applications may be needed.
Pea and bean weevil
Pea and bean weevils are becoming active in winter beans and insecticide sprays may be necessary to control egg-laying in the crop. Spring peas and beans are likely to suffer greater damage, particularly as they are emerging. In spring crops, spray at first signs of weevil notching where there is a history of significant damage. In backward or slow growing winter beans, spraying may be necessary if damage levels are high. Consider which products you wish to use later for control of bruchid beetle in beans and avoid using these for weevil control.
Damage from thrips may also become apparent as spring beans and peas emerge. For the best control of thrips, treatment should be applied as soon as seedling emergence has begun and thrips can be found in the folded leaflets.
The weather is forecast to be settled for a while in many areas. Following rain, conditions for drilling are variable depending on soil type, with some problems on heavier soils. Rolling may help to break up dried clods that have been brought to the surface whilst drilling in relatively wet conditions. This will improve soil surface for pre-emergence herbicides but may cause below ground consolidation in wetter areas. Angled nozzles may be useful where seedbeds are ‘lumpy’ following drilling.
Pre-emergence herbicide choices were outlined in the last PGRO Crop Update - but remember to use up Skirmish in peas and beans by the end of the season. Final use date is 31 December 2013.
Where weeds have not been well controlled in winter beans, crops will be at a suitable growth stage for bentazone applications. The now-increasing temperatures will improve bentazone activity, although a degree or two higher would be even better. The latest time of application is 6-7 leaf pairs.