20 May 1998
Sugar-beet recovery from hail, frost and beetle

Question

MANY sugar-beet crops havent had the best start in life, having had to cope with hail, frost and flea beetles. What can be done to help poor-looking seedlings recover?

Response

Dr Alan Dewar, IACR – Brooms Barn

Answer

HAVING been absent in beet for several years, flea beetles this year are fairly widespread across the country.

Imidacloprid seems to be offering some defence, but even Gaucho-treated crops are suffering some damage, with late-drilled crops at greatest risk.

Hail in some areas may have helped to remove cotyledons, while frost has scorched leaf tips or weakened seedlings by damagaing shoots below ground. The important thing is not to hit these vulnerable crops with too hot a herbicide.

Its probably not worth spraying Gaucho-treated fields because the beetles may well have been controlled already. The damage has been done and cant be repaired.

An additional spray of gamma-HCH would kill many beneficial insects, while something safer such as a pyrethroid wont be very persistent once plants start motoring.

It might well be worthwhile to spray untreated fields, bearing in mind these same considerations. Some warm, dry weather will allow the plants to grow away from these incipient conditions.