Septoria pressure in UK wheat crops is expected to build in the coming weeks, as warmer weather follows early May rainfall. Laboratory analysis of hundreds of plant samples has highlighted significant levels of latent Septoria, indicating that disease pressure could be greater than expected following a cold, dry April.
The Met Office expects a return to more typical May temperatures in the next fortnight and Corteva Agriscience is warning that these conditions could be favourable for Septoria to spread through crops ahead of key flag leaf fungicide applications.
Sally Egerton, UK and Ireland technical manager for Corteva, said: “In general cereal crops have looked reasonably clean and free from disease which led to T0 fungicides either being skipped, or rates being cut back.
“T1 fungicides are going on following very little rain so, again, programmes will have been adjusted according to the perceived level of disease prevalence.
“Now we are seeing reports of high levels of latent Septoria infection which will spread with further rain events and the warmer temperature expected in the next 10-12 days.”
SwiftDetect, Microgenetics’ rapid testing service for Corteva, indicates the infection level using a traffic light system and logs genome equivalents, helping farmers to understand their position before making a decision on the appropriate product and rate for T2 fungicide applications.
Microgenetics said it has not been surprised by the number of positive samples sent from across England and Wales, highlighting the importance of testing.
Chris Steele, product manager for SwiftDetect, said: “We have detected latent Septoria in over 400 samples which have been sent to our laboratory since T1 applications took place.
“Many of the positive samples come from varieties which do not have a strong disease profile, and where growers might expect to find Septoria present, even if it was not visible.
“But we have also had positive samples from varieties which have excellent Septoria ratings, which demonstrates the importance of testing before deciding on product choice and dose rate.
“Once temperatures get to 15 degrees and above, Septoria can really get going.”
Corteva is now advising growers to use a robust product to deliver lasting protection during the key growth stages of the crop. Univoq fungicide, containing Inatreq, was approved for use last month and is said to offer control on all Septoria strains.
Ms Egerton said: “Univoq has the flexibility growers require to adjust their programmes according to their disease risk. We are advising 1.25 litres per hectare in most situations, but that rate can be adjusted up to 1.5l/ha in high-pressure situations, or down to 1.1l/ha.
“Growers will get long-lasting, robust protection from the Inatreq molecule which will also treat any latent infection in the crop.
“Applied at the T2 timing, Univoq will maintain green leaf area and allowing the crop to build yield long after application.”
For more information go to www.corteva.com