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UK SITTING ON A SEPTORIA TIME BOMB
Date added: 12/03/07 |
UK crop producers are sitting on a Septoria time bomb meaning efficacy of T0 sprays in the next few weeks will be absolutely critical to controlling the disease this year, says ProCam technical director Dr. David Ellerton.
Speaking at the company’s Spring Conference in Newmarket on Wednesday 7th March, Dr. Ellerton said the mild winter, combined with reducing fungicide efficacy and the increasing emergence of resistant variants of the disease, are likely to cause crop producers major problems this year.
ProCam 4cast figures from last year show the difference between application of one fungicide spray and a five-spray programme to be worth as much as 4.1 tonnes/ha – from 6.0 tonnes/ha to 10.1 tonnes/ha.
Furthermore, spray intervals of greater than 4 weeks take a further 0.31 tonnes/ha of the yield when compared with intervals of less than 4 weeks.
“Last year, the wet Spring and early Summer made many people extend spray windows to 5-6 weeks as opposed to the optimum 3-4 weeks with significant impact to yields. This year the consequences of doing that could be far worse.”
Particularly worrying was the lower performance of triazoles where 10 years ago a _ dose would achieve 90% control it now gives just a 50% control. 4cast information shows that at the same time as this drop in efficacy, many growers have cut back dose rates from 80% to approximately 50% of a full dose giving even further cause for concern. When used as a curative spray, it’s control reduces even further.
“Producers have got to get on early this year and make sure they are using the product at an appropriate dose rate as a protectant and not a curative if they want to stand any chance of controlling Septoria. They must use the dose to do the job and vary it depending on individual disease risk.”
Work on Tebuconazole over the last two years is also flagging up concerns that all triazoles will face growing resistance in the future. Even at double doses, in some cases Tebuconazole has provided very little protection and the reason is the growing prevalence of I381V mutated variants of the disease which have practically quadrupled in the last 5 years.
“Research has shown that Tebuconazole actually encourages the proliferation of this mutant variety so control is even harder the second time around.
Although it does still work in combination with other products, there is now real concern that all triazoles may go the same way,” Dr. Ellerton said.
As far as Strobs. are concerned, they are still cost-effective at current prices and must be targeted effectively on early drilled, high potential sites, crops under stress or for specific diseases such as rusts, ear diseases or take all.
“This is not a year to take risks with Septoria control,” he concluded.
“There is literally a time- bomb of disease out there and arable farmers must be extra vigilant to make sure they get on early, with the right product at the right dose rate using as many modes of action as possible and not let spray intervals run away with themselves.” |
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