BLIGHT INCIDENCE has been above last year so far this season, with the southwest worst affected, according to the British Potato Council.

But the disease has proved extremely localised in East Anglia and North Lincolnshire, depending on whether spray programmes have been interrupted by isolated heavy showers, said the BPC’s Rob Clayton.

“Two weeks ago we saw a lot of Smith Periods and we are now starting to see the consequence of these on the [blight monitoring] maps.”

East Anglia agronomist John Keer agreed. Parts of North Norfolk in particular had suffered from heavy showers disrupting blight spraying, while Suffolk, Cambridgeshire and Lincolnshire had generally been drier, he said.

The recent fine spell of weather will have allowed many growers affected by heavy showers to catch up with spray programmes, but it is important to stay on guard, Mr Clayton warned.

“This season could go either way, depending on the weather. Plenty of blight inoculum is still lurking in crops and even if it has been subdued by recent dry weather, spores could be washed into the soil later, causing tuber blight.”

Where spraying has been interrupted it may be useful to use a fungicide with strong kick-back activity, he noted.

Growers can keep track of the latest regional blight reports at the BPC’s blight monitoring website, www.potato.org.uk/blight.