Regulate to accumulate in winter oilseed rape this autumn
Regulating the crop canopy and managing disease in the autumn has a significant impact on the final yield potential of winter oilseed rape crops. Unlike last year, this year’s crops are showing much more even, uniform establishment where they had sufficient moisture at drilling and now have good canopies of 4-6 leaves which are still actively growing. Using a PGR fungicide such as Caramba from now on will be beneficial, according to Clare Tucker of BASF.
"Last year we had a huge variation of crop stages and many crops were too small to regulate. This year there are more crops right across the UK that are well advanced and will need growth regulation. Wide ranging 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. Caramba (metconazole) offers both good disease protection against Phoma with some activity on Light Leaf Spot plus the all important first steps in canopy management," says Clare.
She points out that rape plants need a strong rooting system so that nutrient uptake is optimized, that plants are well anchored and the risk of lodging in the spring is reduced. "Caramba will improve 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 Canker girdling the stem later in the spring. Side branches of the rape plant are initiated in the autumn and promoting their development encourages more uniform branching and seed-fill in the spring. The last two autumns have seen rather different crop scenarios, whereas many winter rape crops this year will definitely benefit from growth regulation this autumn."
Clare also reminds growers that Phoma disease risk earlier in the season was regarded as low, as it was so dry, and right up to late October very little Phoma has been seen. "Once there has been sufficient rain, more crops will be at risk. It will be helpful to keep monitoring for Phoma and look for the threshold of 5-10% of plants showing at least one lesion."
"HGCA Phoma trials showed that Caramba matched most other fungicides in terms of yield response, producing an extra yield of 0.35 t/ha, valued at £82 with rape at £235/tonne. You only need a yield response of around 0.07 t/ha to pay for the treatment. Caramba offers excellent protectant activity of at least 4 to 6 weeks."
Caramba’s double benefit of growth regulation and disease control will be just what is needed this year in those crops which have established well and are advancing in growth stages, following the recent rains, she explains.
"But there will be some rape crops that won’t warrant a Caramba treatment. These are crops that are too small, or not actively growing. In this case, start the programme with an alternative fungicide with no growth regulatory effects," says Ms Tucker.
