15 August 1997

Blight relief

DRY weather has come to the rescue of blight-hit potato crops – in the east at least. But vigilance remains the watchword, warns ADAS.

"The disease pressure has been intense," admits East Anglian-based consultant Paul Dover. "Virtually all growers are now on seven-day programmes."

The recent dry spell combined with spray mixtures of full rate cymoxanil + mancozeb (Curzate) or fluazinam (Shirlan) with half rate tin is keeping blight in check remarkably well, he reports. "But blight programmes this year will cost an arm and a leg." Patch desiccation to contain disease foci spotted during treatments has been quite widespread, he says.

With the pressure to spray frequently it is worth remembering that Fazor (maleic hydrazide) for controlling sprouting and preventing infected volunteers next year has no tank-mix recommendation with blight treatments.

, adds Mr Dover. "Applications must be separate and you need good cover. It also needs 24 hours of dry weather post-application. It is very sensitive to wash-off."

This years conditions will prove a good test of manufacturer claims that fluazinam can reduce the risk of tuber blight, comments Devon-based ADAS pathologist David Lockley.