Fungicide application trials conducted by Agrovista over the past two years have shown that big differences in fungicide performance can be achieved by simply changing the application method.
Work on nozzle choice and angling, water volume and spray drift has produced real effects from how products are applied, says technical manager Mark Hemmant, who adds that the trials have similarities to application work carried out on herbicides.
“It’s all about giving practical advice to our customers, so that they can optimise product performance and ultimately yield,” he says.
“The fact that a high percentage of spray days can be lost, due to the weather, means that there’s a great deal of pressure on spray timeliness and application technique.”
Angling nozzles forward by 30° gave an average yield increase of 0.24t/ha, regardless of nozzle type, in high disease pressure situations, he reports.
“But we’ve also had some interesting results from alternating forward-facing nozzles with down-facing ones in its first year, with a mean yield benefit of 0.46t/ha. That work will continue.”
At the T1 timing, using a water volume of 100 litres/ha and nozzles angled alternately to apply Nebula (pyraclostrobin + epoxiconazole + boscalid) gave an extra 0.9t/ha yield. “And the only difference was in the application. It seems as though we’re getting more spray further down the canopy.”
Overall, the lower 100 litres/ha water volume gave a yield benefit of 0.2t/ha, when compared with 200 litres/ha. “It went up as disease pressure increased,” adds Mr Hemmant. “But of course that’s not all. Lower volumes also allow you to cover more ground in a day and get the work completed.”
Air inclusion nozzles proved to be inferior to flat fans, he continues. “But that’s not the whole story with nozzle type. Flat fans limit the number of spray days that you have available, so air inclusion nozzles are better for getting the spraying job done. They’re more practical.”
For this reason, improving the performance of both air inclusion and flat fan nozzles, with the use of adjuvants, has also been investigated by Agrovista.
“There’s no doubt that drift does affect flat fan performance,” he says. “Simply reducing boom height to 50cm from 1m makes a difference to control levels achieved.”
Adding a drift retardant also improved fungicide results, he notes. “But that is undergoing further evaluation. We are not advising that products such as Companion Gold be added to all fungicides at this stage. There are certain product combinations that will cause nozzle blockages.”
A different adjuvant, Transcend, has had the same positive effect with air inclusion nozzles. “As an application aid, it gave consistent benefits of 0.36t/ha.”
That’s useful, says Mr Hemmant, because growers want to be able to use air inclusion nozzles. “They understand that there’s a slight penalty involved. This work shows them that there could be ways of overcoming that.”
For the latest advice, such as which SDHIs to use this season, see our fungicide special