Farmers urged to spray rape crop against fungus

Apr 29 2008 by Sam Wood, The Journal

NORTH EAST farmers are being advised to apply a fungicide early to their rape this year to prevent sclerotinia, agronomy experts have said.

ProCam Group Technical Director Dr David Ellerton said that many rape crops could be at risk and it was important to act before the fungus became established.

“Because of the cold conditions there has been little germination of sclerotinia to date. But if temperatures start to rocket in the next few weeks, germination and petal fall could both start.”

This year is completely different to last year when it comes to sclerotinia, he said. “Last year 34% of the oilseed rape crop was infected with sclerotinia and the timing and severity of the attack took us by surprise.

“This year we are not under the same sort of pressure, as far as we know. But the level of inoculum in the soil will be much higher because of last year and if germination of the sclerotinia coincides with early flowering, we could be in for another problem year.

“It could be this is a year to consider going in earlier when the first flowers are forming in order to protect the stem from infection. If we wait and the weather turns, we may miss the boat”, Dr Ellerton said.

Another important reason to get in early is that all sclerotinia fungicides are protectant in their activity.

High risk crops should be sprayed at early flowering to make sure petals and stems are well protected before infection can occur, he says. Dr Ellerton considers Filan (boscalid) to be the one of the best products for Sclerotinia.

He said: “It is a strong protectant and also offers a physiological boost that many crops will need this year.

“In BASF trials Filan gave an extra yield response of 1.8 t/ha last year, with a calculated margin over input costs of over £400/tonne. But, unfortunately, it may be in short supply.”

A mixture of half-rate Filan with two-thirds rate Charisma (famoxadone plus flusilazole) gave very good results last year, he said.

“Compass (iprodione and thiophanate-methyl) gave very good results on Sclerotinia last year and will be another useful alternative.

“It is a good broad-spectrum fungicide controlling sclerotinia, alternaria and botrytis.”

Amistar (azoxystrobin) can also perform well and it too offers a physiological boost though its greening effects. Proline (prothioconazole) is also an effective product performing well in HGCA trials last season, he said.

Senior agronomist for the ProCam Group, Nick Myers reports that the 4cast agronomy database shows that investing in flowering sprays has resulted in improved yields and margins for a number of years.

He said: “ProCam forecast data shows a strong correlation between yield and fungicide inputs, particularly flowering sprays.

“In 2000-2004 oilseed rape crops which received no fungicide yielded 2.1 tonnes/hectare.

“Crops that received a three-spray fungicide programme – autumn, stem extension and flowering – yielded 3.7 t/ha, a yield benefit of 1.6 t/ha, valued at £576/ha with rape at £360/tonne.”