Sclerotinia rise needs preventative plan

Article taken from the Farmers Guide

With the fall in oilseed rape prices growers are going to have to spend money wisely on their crops in order to protect yield and quality.  Establishment has been varied throughout much of the UK but in general crops have come through the winter well and so growers must focus on canopy management.

Particular attention needs to be paid to disease control in order to maximise yields says Agrovista agronomist Rob Purvis, whose patch in the south east has seen crops establish very well with good potential.

“Sclerotinia is a key disease that in worst case scenarios can reduce yields by 50 per cent,” he says.  “The fruiting bodies of sclerotinia can stay in the soil for years, and tight rotations in past years have exacerbated the problem.  There is no curative control option available for sclerotinia so it must be tackled early.  It’s a very fickle disease, making it very difficult to predict.

“Sclerotinia relies on ascospores release to coincide with petal fall and enough moisture to stick the petals to the stem,” says Mr Purvis.  “A disease that is difficult to predict needs preventative fungicides, but with budgetary pressures as they are, it means growers might be tempted to take a chance and leave crops unprotected.”

The effect of the disease is not noticeable straight away and only appears after flowering with white stems and premature senescence, by which time it is too late and the damage has already been done.

“For this reason I recommend the protectant fungicide Galileo (picoxystrobin) as the start of my sclerotinia two-spray programme because it gives a yield response even in the absence of disease that will more than pay for the fungicide application.  The proven physiological effects of applying Galileo also give better pod security and the integrity of the crop is kept for at least a further seven days.”

Mr Purvis will apply Galileo in April at the yellow bud stage and a second spray using a different mode of action, 2-3 weeks later such as Recital (fluopyram + prothioconazole).  This should see the crop through to harvest.

“The longer the flowering period the more critical a 2-spray programme becomes.  The first Galileo spray is critical to protect yield and the 2nd spray carries on protecting the crop hopefully until the end of flowering.”

The other advantage of using Galileo is that it also adds to the light leaf spot control, which is a disease Mr Purvis has seen increase in prevalence in his area in recent years.

“Light leaf spot used to be only associated with Scotland and the north of England, but is now becoming a major problem further south,” he says.  “Disease levels can be predicted from infection levels in the previous year’s rape crops as well as the summer temperatures.  Levels for 2015 in the south east are predicted to be as high as 95 per cent of crops being infected.  Galileo is a good non-triazole addition to a light leaf spot programme.” 


10 April 2015

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