Northern Ireland has been issued with its first potato blight warning for 2016 by the Agri-Food and Biosciences Institute (AFBI) and CAFRE, Greenmount Campus.

Full infection periods were recorded between June 7 and 12 at sites across Northern Ireland, AFBI has confirmed.

Growers in the North are advised to protect all crops with approved fungicides and application timing and coverage are critical, the Department of Agriculture, Environment and Rural Affairs (DAERA) advises.

No matter how good the product, it says that nothing makes up for a late start, stretched intervals or areas left unprotected.

Once blight has got a foot-hold in the crop, it’s almost impossible to eradicate it. Angled nozzles with a medium spray quality give better canopy cover at all stages of growth, it recommends.

DAERA advises growers to start protecting the crop from blight whenever the first blight warning is issued or when plants meet within drills (whichever is earlier).

Key tips on spraying for blight

One basic principle must be applied to all applications; sufficient dose, in sufficient concentration and sufficiently even on the target, according to DAERA.

It advises that spraying for potato blight can be a compromise between treating the entire crop on time and achieving optimum crop cover.

It recommends that timing is more important than fungicide product choice or perfect coverage.

During marginal weather the use of air-induction nozzles may help to keep to the correct interval, however, good coverage is essential - particularly to prevent tuber blight.

Extending intervals between applications during high blight risk should be avoided, DAERA says. One day early is better than one day late, although it says that this is restricted by some product labels.

During the phase of rapid growth, good coverage of the growing point is essential:

  • Treat all parts of a potato crop.
  • Missed areas will become infected and create a high disease pressure.
  • Avoid planting parts of fields where spraying is difficult (e.g. around telegraph poles).