Sclerotinia symptoms can mask other trouble
Sclerotinia symptoms can mask other trouble
SCLEROTINIA is another disease which may have compromised seed health this year.
Although increasingly common it is not usually of any consequence in potatoes. But its symptoms can mask other troubles.
Rissing in importance due to a build-up of oilseed rape in rotations which include seed potatoes, sclerotinia initially turns leaves yellow, but then goes on to cause mottling, which can mask virus symptoms.
Usually Sclerotinia affected potatoes occur in patches, but in the most severe cases this year one or more stems on most plants were affected.
There is no evidence to suggest the level of virus in seed, whether obscured by Sclerotinia or not, is any better or worse than normal this season, notes Mr Dover.
"As usual, growers with once-grown home-saved seed should have it checked for virus," he stresses. "Already some crops have been rejected for seed, so the problem is with us." *
Know your enemy to avoid confusion
Make sure you know your enemy, advises ADASs Denis Buckley. The wet June makes soil- and seed-borne pink rot potentially a big problem. The disease is often confused with tuber blight, he says.
"We are already seeing misdiagnosis but in well ventilated stores pink rot will mummify." There is also plenty of blight about on stems which is being missed by growers, he warns.
Store refrigeration offers a better chance of containing low levels of soft rots developing on the back of blight. "But it is no guarantee."
"Just because you have not seen foliage blight do not assume there is no tuber blight present, especially in Pentland Dell and other varieties which have low tuber blight resistance," advises colleague Paul Dover.