Timely T2 sprays will be critical this season following disruption to T0 and T1 spraying in many areas, says Hertfordshire-based agronomists, ProCam.
In some areas T0’s have been missed completely and made up by robust rates at T1, while others may miss T1, hoping to make it up at T2, said the firm’s Steve Wolff.
“If you’ve managed to make T0 and T1 sprays you must stick to a four spray programme, but if your early sprays have been compromised you must make an appropriate T2 spray ensuring it is no more than four weeks after the last spray was applied.”
The firm’s 4cast data shows that every time a spray is missed from a model four spray programme, there is a yield loss of 0.3t/ha.
The maximum four week timing is critical to prevent key diseases such as septoria (in wheat), rhynchosporium (barley) and phoma canker/ sclerotinia/ alternaria (oilseed rape) from getting established, he added.
“Once septoria gets established, there is little you can do to stop it. Leave it [control] longer [than four weeks] and you’ll be applying much higher rates of triazoles than necessary. Interval is definitely more critical this year than the precise stage of growth.”
To keep track of what’s going on in the field, direct from a team of agronomists around the country, see FWi’s Crop Watch – updated every Tuesday.