A septoria warning has been issued to UK growers as high levels of latent disease has been found in plant samples.
Septoria pressure in wheat crops is expected to build in the coming weeks as warmer temperatures are set to follow early May rainfall.
Laboratory analysis of plant samples has shown high levels of latent septoria, which indicates disease pressure could be greater than expected following a cold dry April.
Corteva Agriscience warns that the conditions could be favourable for septoria to spread through crops ahead of key flag-leaf fungicide applications which take place from mid-May.
Sally Egerton, technical manager 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.”
Microgenetics’ rapid test for septoria, SwiftDetect, indicates the level of infection using a traffic light system and log genome equivalents.
This helps farmers to understand their position before making a decision on the appropriate product and rate for a T2 fungicide spray.
Microgenetics said it had not been surprised by the number of positive samples sent in from fields across England and Wales, highlighting the importance of testing.
Chris Steele, the firm's product manager, said they had detected latent septoria in over 400 samples sent to their 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," he said.
“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,” Mr Steele said.
Corteva Agriscience has advised growers to use a robust product which will deliver lasting protection during a key growth stage of the crop.
Univoq fungicide, containing Inatreq active, was approved for sale and use in the UK last month and offers protectant control on all septoria strains.
The product is the first new target site for septoria control registered in the UK for 15 years.
