Don’t compromise late-season fungicides, growers warned, after increased disease risk
Winter wheat growers are being urged not to compromise T3 ear fungicide sprays and timings after rain events in May, even if not long since applying the previous T2 spray.
According to Syngenta cereal disease control specialist, Andrew Curtis, disease pressure has increased following the significant rain events that most growers had in mid-May.
Safeguard this year’s crop potential by maintaining correctly-timed T3 fungicides, urges Syngenta disease control specialist, Andrew Curtis, even if not long since applying the previous T2 spray
The use of appropriate T2 fungicides should have protected the flag leaf and leaf two, he says, but other issues need to be considered at T3 to maximise this year’s crop potential.
“Infection of ears with Fusarium, which is driven by wet weather during flowering, is obviously a key consideration at T3,” says Mr Curtis. “However, other ear diseases – such as sooty moulds and Cladosporium – as well as late-season foliar diseases, and the risks that these pose to grain quality, plus to green leaf area and yield, also need to be taken into account. Every extra day of green leaf area retention after flowering has been shown to increase yield by 0.15 t/ha.
“With Fusarium control, achieving the correct spray timing of early to mid-flowering with a Fusarium-active triazole fungicide is the key factor. Even if T2 flag leaf sprays were applied late, it is still important not to compromise the Fusarium spray timing,” he adds.
“Which particular Fusarium-active triazole is used can be based on the foliar diseases present. However, triazoles won’t control all diseases at T3, so to compliment Fusarium activity, the addition of the strobilurin Amistar Opti has been proven to improve disease control – including late rusts, Cladosporium and glume blotch,” he points out.
Commenting further on the importance of maintaining late-season green leaf area, Mr Curtis says the flag leaf contributes over 40% to yield, with the ear contributing over 20%. He says the proven greening effect of adding a strobilurin can help retain green leaf area even in the absence of disease.
“It is a long time until harvest. If you don’t achieve adequate T3 protection, or omit a T3 fungicide altogether, you are expecting a lot from a T2 spray, which is typically applied during May.
“Adding Amistar Opti to a Fusarium-active triazole at T3 has increased yield by 0.3 t/ha in trials.”