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Keep on top of Sclerotinia in oilseed rape
Date added: 16/04/10 |
Researchers at Rothamsted Research report that sclerotia of the damaging oilseed rape disease Sclerotinia have just started to germinate and the BASF/ADAS Sclerotinia Monitoring tool indicates the same.
With most fungicides for Sclerotinia in winter oilseed rape being protectant, an early start and a planned programme covering the critical infection phases will be important to keep this disease out, says Dr. Dave Ellerton of ProCam UK Ltd.
Sclerotinia erodes yields by causing premature senescence, reducing seed weight and causing early seed loss, he explains.
“A comprehensive two-spray fungicide programme to protect the crop from this damaging disease makes economic sense in most years and this year will be no exception.
“But timing is key to success. In thicker crops the programme should start at yellow bud stage with a PGR fungicide such as metconazole (Juventus). This helps to reduce lodging, evens up the canopy, synchronises flowering, improves branching and protects against early infection of the flowers by Sclerotinia spores.”
Dr. Ellerton points out that oilseed rape crops are now rocketing away and many crops are at mid-stem extension stage and the most advanced at early flowering.
“Now is the time to apply Juventus on these more advanced or thicker crops. This fungicide does a very good job as a PGR and offers a good start to Sclerotinia control during early flowering. If a PGR isn’t needed, then wait until a specific Sclerotinia is required.
“This first spray should then be followed three weeks later by a more robust fungicide treatment with specific activity on Sclerotinia such as Filan (boscalid) or Galileo (picoxystrobin).
“What you are trying to do is to keep the canopy green and to protect the crop from disease for as long as possible at the start of the yield building phase,” he says.
The BASF/ADAS Sclerotinia Monitoring tool on www.totaloilseedcare.co.uk website is a valuable planning tool, Dr Ellerton says.
“The site indicates when sclerotia germinate and form apothecia or mushrooms which in turn release spores that attack the crop. It is useful to see when the disease pressure is likely to be raised. Last year the first sclerotia started to germinate in late March but this year we have had to wait for the warmer soil conditions of around 10°C.”
Although Sclerotinia wasn’t at such a high level last year, the previous two years 2008 and 2007, had very high levels and this means that the risk will be high on most farms, particularly those growing rape in tight rotations, Dr. Ellerton warns.
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