Recognising the difference between growth and development was important last year, as was the responsiveness of varieties to fungicides, says NIAB TAG technical director Bill Clark.
“In both cases, the two are not the same. Crops that appeared very forward and tall early on were still at their expected growth stages, while some varieties with high resistance ratings proved very responsive to fungicides.”
Accurate spray timing was essential, with T0 and T1 sprays applied in good conditions and helping to keep disease in check.
“We can’t farm with hindsight,” says Mr Clark. “There was a change in the weather just ahead of the flag leaf spray, so it was good that most growers resisted the urge to make drastic reductions early on or had gone too early and stretched spray intervals.”
NIAB trials support the use of fungicide programmes based on better chemistry and tighter spray intervals, costing an extra £52/ha, regardless of conditions, he reveals.
“In 90 comparisons with ten varieties across three sites and three years, it was more profitable to use the more expensive programme on all the varieties in every season. In a bad year, there’s a great deal to lose.”
However, he accepts 2017 was not a bad year. “Our trials just from last year are less conclusive, with cheaper programmes doing well on some southern sites. But there was no justification for omitting sprays.”
Mr Clark’s final lesson from 2017 was that some of the highest levels of brown rust were seen after it came in late, helped by high temperatures.
“The disease became very active in early/ mid-July, just as crops reached maximum dry matter. So applying fungicides to prolong grain filling didn’t have any effect and were just vengeance sprays.”
The season highlighted the number of varieties that can get high levels of brown rust and showed why control needs a different approach to yellow rust, he adds.
“On the whole, ear sprays aimed at Fusarium did a good job on brown rust as well.”
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