Bill Clark, newly appointed Commercial Technical director at NIAB TAG is warning against any complacency when it comes to yellow rust; with levels of active rust currently increasing dramatically across a wide range of varieties.
"The hard frosts of a few weeks ago have not diminished the progress of yellow rust – and it’s important to remember that if there is active rust in the crop, the crop is at risk. Getting on top of the epidemic as early as possible is key," says Mr Clark.
"Oakley, still very widely grown because of its high yields, is frequently reported as having symptoms – no surprise there - but many other varieties are now also showing symptoms. The varieties most at risk which need checking are Conqueror, Ketchum, KWS Podium, Solstice, KWS Santiago, Torch, Viscount and Warrior.
"The UKCPVS information can give some guidance on prioritising varieties. If you do see symptoms on any variety send off a sample with details of the variety and location to NIAB UKCPVS in Cambridge."
"Active rust means you have to act – don’t wait for your next normal timing – and don’t get hung up on T0, pre T1 and so on. Just get in there as soon as you see active rust. With these very susceptible varieties the disease can quickly get away from you, even high doses at T1 will not always recover a situation gone wrong," he advises.
"Triazoles and strobilurins are the fungicides of choice at the earlier stages. A triazole plus strob will give you both good eradicant and protectant activity."
Peter Hughes from BASF, reminds growers and agronomists of the data from the most recent HGCA trials which confirm Comet 200, containing the most effective rust-active strobilurin pyraclostrobin, protects yield from yellow rust at typically used field-dose rates of around 0.4L/ha.
"At the average field dose of 0.4L/ha, Comet 200 is highly cost effective for saving yield in the presence of yellow rust. In one particular HGCA trial (see below), 0.4L/ha Comet 200 is giving a yield uplift of over 1.5t/ha, worth £225/ha (@ grain price £150/t). For a cost of approximately £10/ha, you get £225/ha back. You won’t see this level of return at all spray timings, but it gives a strong indication of relative performance of Comet 200 against yellow rust."
"With the yellow rust epidemic that is currently spreading around parts of eastern and northern England, make sure you order Comet 200 to use at T1 for use in combination with triazole-based products such as Tracker. Pyraclostrobin in Comet 200 provides a different mode of action, which is crucial to protect the existing and new fungicide tools we have from being exposed to resistance development."
