A combination of single and multisite chemistry will keep crops protected for longer, says Adama technical manager David Griffiths.
“The T2 fungicide timing is the most critical treatment for the protection of wheat crops as its application at GS37-39 provides the ideal opportunity to ensure the main light-capturing leaves – leaf 2 and the newly emerged flag leaf – remain clean and free of the dominant yield-robbing diseases, septoria tritici and rusts,” David explains.
Even though weather conditions have been relatively favourable in recent weeks, he says there is still plenty of both diseases present in crops. “Any disease spores sitting in the lower canopy could easily be transmitted onto the upper two leaves during heavy rainfall events, so a robust fungicide treatment is a must to keep both leaves as clean and green for as long as possible.”
The inclusion of an azole and/or an SDHI/Qil fungicide will provide a certain amount of curative activity, he acknowledges but because they only work against one biochemical pathway within their target pathogen, these single-site chemistries are more prone to sensitivity shifts or mutations, which make septoria populations resistant and therefore harder to control.
“A T2 treatment based solely on single-site actives won’t therefore be enough to keep crops protected as they progress towards maturity. For that reason, a multi-site fungicide such as Arizona (500g/l folpet) should be included to provide greater longevity of protection,” he says.
He adds that it is the only fungicide that has been proven to extend the effective lifetime of single-site fungicides by delaying and reducing their susceptibility to resistance. “Adding Arizona to the tank mix can also help to enhance the efficacy of single-site chemistries, resulting in better yields at harvest.
Seven years of independent trials showing that its inclusion boosts yield by an average of 0.14t/ha across dry and wet seasons,” David concludes.
