A bank holiday weekend of rain and thundery showers topped up what had already been the wettest May since 1983. Spray days in May were precious few, putting many growers behind, and potato agronomists are now warning of knock-on implications for blight programmes.
Although potato plantings have been completed by the same time as last year many were delayed to the second half. "Many cereal programmes are behind and there are still a lot of potato herbicide applications to go on," reports Agrovista's Mark Palmer. "There's a lot of catching up to do so it's going to be a tricky season for blight programmes.
"A lot of spuds are already through, and May's high rainfall means they're now set to grow very fast, as should the later plantings when they emerge. Add to this the backlog of sprayer work in general and systemic protection of rapid haulm growth will be even more critical than usual. It's not going to be a season for relying on contacts and translaminars."
With four outbreaks on outgrade piles already confirmed by the BPC in Kent, Lincolnshire and Suffolk, Dr Palmer urges growers to plan for robust protection from the start. "Growers will need to be using highly mobile systemics, like Consento or Tattoo, to give rapid new growth the necessary protection. Being propamocarb based they offer multi-site activity and will control all blight strains, including A2 and phenylamide resistant.
"Consento delivers a very strong combination of actives. Fenamidone contributes foliar activity and along with propamocarb builds in early tuber protection. In trials we've seen a significant relationship between early use of propamocarb-based systemics and control of tuber blight.
Despite less than ideal soil conditions at the start of May Scottish growers mostly had planted wrapped up by the end of the month. "Current showery and windy conditions are not ideal for herbicide applications to potatoes or cereals though," says CSC's Mark Ballingall. "The priority for blight programmes, when they get underway in June, will be to control outgrade piles and any infector shoot issues so we'll be recommending growers to start with a T0 application of Tanos."
Having also witnessed the relationship between rapid haulm growth protection and tuber blight control Mr Ballingall supports the use of systemics. "Generally we'll be starting the rapid haulm stage with Tairel then switching to Consento followed by a further application of Consento or Merlin where necessary – both benefit from propamocarb's early activity against tuber blight."
CSC's spray interval advice this season will be guided by Forecast Xtra's five-day blight pressure forecasting. "Under low pressure we've extended intervals from seven to 11 or 12 days with confidence," he reports. "Justification of blight programmes with decision support systems will become more and more essential to comply with retailer protocols."
