With Sclerotinia being such a significant problem in many oilseed rape crops, it has become even more important to monitor disease risk and decide on the need for, and timing of, a protectant fungicide treatment. This year the Sclerotinia germination monitoring service on the www.totaloilseedcare.co.uk website has been added to by a petal culture test, so that disease risk can be more accurately assessed.
"ADAS and BASF have run this web-based germination monitoring service for six years and it has proved to be a useful management tool to assess disease risk and the need for treatment. It monitors the germination of the pathogen's resting stage, the sclerotia, buried in fields of winter oilseed rape crops at six sites in Cambridgeshire, Yorkshire, Herefordshire, Lincolnshire, Kent and Edinburgh. Germination assessments are made each week for twelve weeks and the service is updated on the www.totaloilseedcare.co.uk website each Friday. Already germination has been seen at ADAS Rosemaund in mid March. Sclerotia germination increases once the soil temperature has reached 10˚C provided the soil surface is moist. The sclerotia then release air-borne spores, which infect oilseed rape petals. Crops are usually at high risk if sclerotia germination is synchronised with early flowering," explains Clare Tucker, Agronomy Manager for BASF.
Last year however proved to be an odd year when Sclerotinia was found at a higher than predicted level. "So in addition to the sclerotia germination test, we are also using a petal culture test. This test is a useful technique for establishing disease pressure from air-borne spores and the data collected is used in conjunction with the sclerotial germination test to more accurately predict the risk of an epidemic," explains Clare.
"Filan (boscalid) is the current standard treatment against Sclerotinia and where there is a history of Sclerotinia problems on the farm, growers should be preparing to apply this protectant at the early to mid-flowering stage" says Clare.
"Filan is the proven Sclerotinia fungicide, performing well in trials and in commercial use over many years. It gives reliable and consistent protection against Sclerotinia, as well as broad-spectrum activity against Alternaria and Botrytis. It has good persistence allowing application at early flowering. Unlike triazole fungicides, it can be tank-mixed with a pyrethroid insecticide for pest control. Filan is recommended at a dose rate of 0.5 kg/ha at early to full flowering before disease symptoms are visible," says Clare.
Compass, which contains iprodione and thiophanate-methyl, has also performed well in independent Sclerotinia trials and offers an alternative to Filan. "Both products are protectants and so you will need to get them on before you get any significant petal fall."
For further comment and information please contact Clare Tucker, BASF on 01458 259220 or 07768 687707 (mobile)
