Black bean aphid pressure is still high in bean crops, althoughmany field beans will be past the stage where yield impact is likely, notes,PGRO principal technical officer, Becky Ward. Where pods are stillfilling in field beans or broad beans, aphicides should be applied when 10% of plantsare infested.
She also notes that sclerotinia infection in vining peas has beenrelatively high in 2015 and the risk will remain high in areas where warm,humid conditions are experienced.
Late crops of vining peas and dwarf French beans continue to be susceptible toinfection. sclerotinia sclerotiorum affects a wide range of cropsincluding vegetables, potatoes, linseed, oilseed rape and sunflowers as well asspring beans and peas (winter beans are affected by sclerotinia trifoliorum).
Individual or groups of plants may beinfected in discrete areas in the field. This is usually noticed in early tomid-summer when weather has been wet and warm. Stems become covered in whitemycelium and may collapse as the infection develops. Infected stems and podsmay contain black resting bodies, sclerotia, which are returned to the soilwhere they can remain for several years.
As well as yield loss, pea and beanproduce may be contaminated with sclerotia, which are difficult to remove infactory processes.
Sclerotia in the soil produce smallapothecia, which release spores into the air. These adhere to stems or flowerpetals and infect the plant tissue. A rotation of 4 or 5 years without a hostcrop helps to reduce disease risk and, where disease is expected, apreventative fungicide should be applied during flowering.