Oilseed rape crops treated with flusilazole this autumn for phoma infections may be better placed to take up nutrients earlier and more effectively next spring, and have greater drought tolerance, according to results from eastern European DuPont trials.

The trials, carried out in the Czech Republic last autumn, found flusilazole treatment increased tap root mass on average by over 15% compared with untreated plots, while stem base diameter was nearly 10% greater.

“Having a better root system means the crop will survive winter better and be in a better position to take up nutrients and water more effectively, and earlier, in the spring,” says the firm’s Colin Allott.

Other research suggests oilseed rape crops require tap roots at least 40cm long to help them get through periods of spring drought, adds his colleague Adrian Sissons.

“If anything affects tap root development, either positively or negatively, it will have an effect on yields.”

Across the eight Czech trials yields increased by 6% following flusilazole treatment.

Other oilseed rape fungicides applied in the trials had similar effects, admits Mr Allott.

“Both Caramba and Folicur also increased tap root weight and stem base diameter, although not by as much as Sanction.

And neither is as active against disease.”

The positive effects of flusilazole treatment are well known commercially, notes Suffolk Crop Protection agronomist Nigel Jennings.

“Several of my growers have noticed how flusilazole-treated crops within a week perk up.”

He’s not surprised that could be due to a positive effect on tap root development.

“A good tap root is absolutely crucial for successful crops.

You must get the underground part of the plant right.”

Flusilazole will again form a key part of his fungicide strategy for this season.

“The rooting effect could make it worth treating with, even in the absence of phoma.”

Phoma, however, could be about to explode, he suspects.

“It has been delayed because of the dry, but now we’ve had some rain we are starting to see some lesions.

If it stays mild and wet it could build up very quickly.”

Most of his crops are drilled during the more traditional establishment period of late August or early September, he says.

“That means they have normally made as much height as I want them to by the end of October.

I don’t want them to get any taller, but I also don’t need to shorten them either.”

The exception might be some very forward crops drilled earlier in August, he says.

“If you’ve got a crop already as high as the top of your welly boots, and still growing, that might be the place for Caramba [growth regulatory effects].

Luckily I don’t have any crops that far forward.”

mike.abram@rbi.co.uk