Higher doses are likely to be required in GS32 wheat fungicide sprays after the majority of growers failed to apply T0 clean-up sprays because of poor weather, according to agronomists.
Only 5-10% of North Yorks based Robertson Crop Services agronomist Mark Wood’s customer’s crops had been applied with a T0, he estimated earlier this week.
“I would have hoped for much more, particularly on forward crops.
Last year more like 50-60% were treated.”
The reason is mostly weather-related, although workload is another factor, he explained.
“Growers have been drilling and top-dressing, rather than spraying.
It is definitely a T1 market rather than T0 now.”
Unsprayed wheat crops were “mucky”, he said.
“Septoria is pretty bad in the varieties you would expect, such as Consort, and you can find it in Robigus, along with mildew.”
It would probably cost growers some yield, he said.
“You want to keep disease out from the word go, so it will certainly have had an effect, maybe only 2-3%, but with the current economics growers cannot afford any hit.”
East Anglia-based AICC agronomist Ruth East also reported only small numbers of T0 sprays actually being applied, but denied it was a big concern.
“I’ve only had two clients out of 20 who have got their T0 on, but I’m not worried.
“The superficial disease pressure has disappeared, although there is still inoculum in the crop.
Luckily we haven’t had the conditions for the spread of septoria, mildew or yellow rust.
A good, well-timed T1 should take care of it.”
Growers advised by Phoenix Agronomy’s Paul Power had had a little more success in applying T0s.
“I recommended 70-80% to do it, and maybe half has been done.
It is a real mixed bag.”
Those who hadn’t managed to apply a T0 would need to apply a more robust T1 spray, he said.
“I’ll be looking at a bigger dose of triazole, plus chlorothalonil, and maybe some morpholine on potential rust and mildew varieties.”
Mr Wood would also be changing his T1 recommendations where T0s hadn’t been applied.
“I’ll have to use more robust materials with a greater kickback now, rather than the cheaper materials [I was considering].”
But where T0s had been applied crops would be revisited in the next week to assess whether reduced doses and different chemistry could be used, he added.
On those crops the total fungicide bill for T0 and T1 might be slightly less than where only T1s would be applied, he suggested.
Timing would also need to be watched carefully, Mr Power noted.
“Growers haven’t got as much time as if the T0 had been applied.
Ideally I want T1s to go on in the next seven days.”
Scottish Agronomy’s Allen Scobie agreed timing and content would now be more important than usual.
“Everything needs to be a little more robust.
And you need to be sure you don’t miss it.
A T0 would have bought some flexibility if you were waiting around for the weather.”
Growers who hadn’t applied a T0 should err on the side of spraying earlier rather than later, he advised.