T2 fungicides must be carefully timed this season as rainfall since T1 applications is likely to have increased septoria pressure in some parts of the UK.
Early drilled crops in the west of the country are particularly vulnerable, although there is quite a large variation in disease pressure across the country.
Rebecca Joynt, crop pathologist at ADAS says: “There is noticeable East/West divide where there was a big difference in rainfall in April. The ADAS site at Rosemaund in Herefordshire received 60mm of rain in April, 13mm above the 30-year average. In contrast, the ADAS site at Boxworth in Cambridge received 9mm of rainfall, compared to a 44mm average for April.”
However, growers in the East should still be vigilant because rainfall over the last week will have increased disease pressure across the whole country.
The warm weather over Easter accelerated crop growth, although this has been checked by the cooler temperatures since then meaning crops are generally where they should be for this time of year, according to Ms Joynt.
ADAS’ Crop Action reports suggest that the flag leaf is emerging in most crops in the South, with varieties like Extase more forward, up to half a leaf ahead of others.
Ms Joynt says: “It is about making sure T2 applications are well timed to protect the flag leaf. For wheat, the T2 fungicide application is the most important for yield formation.
A strategy focussed on the SDHIs in combination with leading triazoles should provide robust disease control in high pressure situations.”
The use of multi-site actives at this time is also likely to improve disease control of septoria and yield and will ensure a level of control is maintained in resistant populations, she adds.