The continuing weather is encouraging the development of ear diseases and growers who have already invested in their cereal crops at T0, T1 and T2 timings should continue to protect that investment with a robust T3 fungicide treatment this year, says Dr. David Ellerton of Hutchinsons.
Dr. Ellerton reports that Fusarium inoculum is much higher this spring than it has been for a number of years and this, together with a high disease year for foliar diseases including Septoria and rusts, will mean that most crops will benefit from a robust T3 spray. “Application timing is always important. Normally the T3 treatment should go on as close to early flowering as possible. This means that the fungicide is more likely to be effective against Fusarium species which impact on quality and produce harmful mycotoxins, as well as protecting against yield robbing diseases such as Septoria and rusts.”
“The aim of the T3 treatment is to control ear diseases and also to continue protecting the top two leaves against foliar diseases such as Septoria and rusts. The pressure is on this year to make sure that the T3 spray provides this broad-spectrum of activity on a range of foliar and ear diseases and that it is applied in time. The weather hasn’t made fungicide applications that easy. The T3 treatment needs to provide both protectant and eradicant activity and preferably should have a multi-site element, as a disease resistance precaution” says Dr. Ellerton.
A tank mix of the double triazole Veto and the double multi-site Guru will tick all these boxes, according to Dr. David Stormonth, Technical Manager for Interfarm. He explains that Veto contains tebuconazole and triadimenol, two strong triazoles that have different systemic rates and so protect the plant more effectively from disease. “Guru contains two multi-site protectants, mancozeb and chlorothalonil and so offers double the contact protection,” he says.
“The double multi-site fungicide Guru will add to Septoria protection as well as providing robust protection from ear diseases, including Fusarium, Microdochium and sooty moulds, as well as mildew, brown rust and yellow rust. Mixing with a double acting triazole such as Veto will significantly lift the protection against damaging ear diseases.”
Both Davids advise growers to assess their own disease and mycotoxin risk. Wheat for human consumption will need more comprehensive protection against Fusarium species in order to prevent either DON or ZEAR mycotoxin levels from being exceeded, especially if grain is destined for infant food where legal limits are lowest: They are both of the view that this year could see a serious disease risk with the threat already being higher than usual.
“This season we have seen much higher Septoria and yellow rusts levels in wheat than for many years. And it also looks to be potentially a high Fusarium year. The two mycotoxin-producing Fusarium graminearum and F. culmorum flourished in the warm dry early spring and this encouraged inoculum to build on crop debris, whilst the wet April helped F. culmorum to spread by rain-splash onto the crop. More Microdochium has been spotted in crops too, due to the mild winter,” concludes Dr. Stormonth.
