Optimising the crop canopy plus managing disease in the autumn has had a significant impact on the final yield potential of winter oilseed rape crops this harvest. This autumn many growers have decided to drill their oilseed rape early and already some crops have strong actively growing canopies of 4-6 leaves. Using a PGR fungicide such as Sunorg Pro this autumn could be a beneficial option, especially as disease risk is also likely to be high, according to Jon Williams of BASF.

"A lot of oilseed growers achieved the best yields they have ever had this last harvest. These exceptional yields have been put down to good crop establishment together with the development of strong root systems plus complete attention to detail throughout the crop’s life. Well established crops with strong roots seemed to be able to ride out the cold winter and then the severe drought in the spring and still go on to produce top yields. Consequently many growers have decided to drill their rape early, with a view to building on last year’s successful strategy," says Jon.

Small canopies produce best yield

Jon reports that there are many more advanced rape crops that could require growth regulation as well as disease control this autumn. "Research work by ADAS has shown that small canopies produced the best yields and the autumn is where you start manipulating the plants to optimise these canopies. Sunorg Pro (metconazole) offers both good disease protection against Phoma stem canker, with some activity on Light Leaf Spot plus the all important first steps in canopy management."

Phoma warning

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Jon Williams reminds growers to monitor crops for Phoma, looking for the threshold of 5-10% of plants showing at least one lesion, and be prepared to spray within two weeks of the symptoms appearing. "HGCA Phoma trials showed that Sunorg Pro matched most other fungicides in terms of yield response, producing an extra yield of 0.35 t/ha, valued at £130 with rape at £375/tonne. Sunorg Pro offers excellent protectant activity of at least 4 to 6 weeks."

Rooting improved

Jon points out that metconazole is the proven PGR fungicide. "It improves the rooting structure of the oilseed rape as well as regulating plant height, keeping the canopy closer to the ground and helping the crop through the winter. Shorter and thicker lower stems mean better winter hardiness and less chance of stem canker girdling the stem later in the spring. Side branching is also initiated in the autumn and promoting their development encourages more uniform branching and seed-fill. But inevitably there will be some rape crops in some locations that won’t warrant a metconazole treatment. These are crops that are too small, under stress or not actively growing. In this case, start the programme with an alternative fungicide with no growth regulatory effects," says Jon Williams.

Sunorg Pro's double benefit of growth regulation and disease control is just what is needed in those crops which have established well and are advancing in growth stages.