‘Don’t scrimp on T3 sprays’ warning – Farmers Weekly
Wheat growers are being warned not to economise on T3 sprays and risk exposing emerging wheat ears in such a wet high disease pressure year ...
Of all the main fungicides, the T3 treatment is one where growers might look to make savings, but in a season such as this, that could be very risky, says Hutchinsons head of integrated crop management, David Howard.
Main fungicide
T3 (growth stage 63-65) is the main fungicide timing to protect wheat ears against fusarium, between ear emergence and harvest. However, the wet weather this season has led to high levels of rusts and septoria in crops, which remain a threat to yield.
He says the T3 could also hold much greater importance for topping-up foliar disease control, notably septoria and rusts, thereby helping preserve green leaf area further into the summer growing season.
Timing for best control
David advises that T3 sprays should be applied as soon as ear emergence is complete and flowering is under way (GS63-65), but before
florets are visible.
This will give the best control of fusarium in warm, wet conditions and microdochium in the cool and wet.
The unsettled weather of the past three months could lead to variable and protracted ear emergence, making it more difficult for growers to spray at the right time. However, delaying the T3 spray will result in poor dis- ease control. David says: “It is better to be a little early than a little late.”
Factors affecting choice of a T3 fungicide include varietal susceptibility, any diseases present, chemistry used at T2 (growth stage 39) and the weather forecast.
Guide to T3 Fungicides
David Howard suggests these active ingredients to combat diseases:
Fusarium/DON mycotoxins
- Metconazole, prothioconazole or tebuconazole
- AHDB and ADAS trials suggest best results from prothioconazole and tebuconazole
- Phosphites at ear emergence can reduce DON production
Yellow and brown rusts
- Metconazole or tebuconazole (or when two SDHIs have not been used)
- Fluxapyroxad + metconazole
- Benzovindiflupyr + prothioconazole
Michrodochium nivale
- Prothioconazole
Septoria (when two SDHIS have been used)
- Prothioconazole + fluoxastrobin/tebuconazole
Septoria (when two SDHIS have not been used)
- Bixafen + prothioconazole/tebuconazole
- Fluopyram + prothioconazole/tebuconazole
- If not already used – fenpicoxamid+ prothioconazole
Rusts, septoria nodorum, sooty moulds (if two strobilurins have not been applied).
These must be applied with a fungicide with a different action.
- Fluoxastrobin, pyraclostrobin, azoxystrobin
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