WEEDBEETis big worry
WEEDBEETis big worry
Sugar beet was to have occupied a key area at the Cereals 2001 event near Royston,
Herts. Edward Long provides a summary of some of the key messages growers would
have received, including weed beet, crop protection and variety choice
Sugar beet was to have occupied a key area at the Cereals 2001 event near Royston,
Herts. Edward Long provides a summary of some of the key messages growers would
have received, including weed beet, crop protection and variety choice
EARLIER hopes that weather-induced delays to sugar beet drilling would ease the weed beet threat this season have been dashed by the cold spring. Now growers are being urged to maintain the pressure on the yield-crippling weed.
It had been expected that seedling weed plants would have been killed by pre-sowing cultivations. But with low temperatures few appeared.
"Last season 64% of beet crops were infested and just 8sq m, which is quite common, can halve yields," warns Simon Fisher of British Sugar. "But where the population reaches 50/sq m root yield is slashed to 10t/ha and at higher infestations yield is totally obliterated."
Infestations can shoot up from almost nothing to yield-wrecking levels in just a few years if nothing is done, he warns. A single plant can produce 1500 seeds that remain viable in soil for at least 20 years.
The problem is getting more serious every year. Last years build-up was masked by higher than normal numbers of conventional bolters. But that is unlikely to occur this season, so there is a chance to get on top of the problem, advises BS.
Where weed beet are present repeated tractor hoeing will control those growing between rows. Hand pulling and removing is 100% effective if the infestation is 1000/ha or less. Up to 10 times that number can be handled by weed wiping, with two passes in opposite directions. At greater densities mowing tops off rogue beet to prevent seed shed is a last resort.
Gaucho benefits
Last winters monsoon-like weather was not kind to over-wintering aphids and forecasts issued by IACR Brooms Barn in March indicated they would not be a serious problem in the 2001 crop. "So the use of Gaucho to control just aphids would not have been economic this season," says Brooms Barns Mike May. "However, most growers use it to control other pests, such as millipedes, symphylids and springtails, as well as aphids. These will not have gone away so the treatment was still worthwhile."
Weed beet problems will be worse this year after cold conditions at sowing more than offset the later start, says BSs Simon Fisher.