Spider mite is beet concern
Spider mite is beet concern
A RED coloured spider mite has been revelling in the late summer heat-wave, raising concerns that infestations could hit sugar beet crops.
Serious damage has already been recorded in a Suffolk trial. Researchers are now keen to discover the extent of trouble in commercial crops.
The tiny, two-spotted spider mite, Tetranychus urticae, turns red in the autumn, so is easily confused with its red cousin which affects horticultural crops. Continental research suggests yield losses of 20-30%.
The pest was first confirmed on beet in Norfolk, Suffolk and Cambs in 1995. In both 1995 and 1996 it caused severe damage in trials at IACR Brooms Barn where artificially introduced infestations have again caused severe trouble this year.
The pinhead sized mite feeds on leaves, damage initially showing as pale yellowing between green veins, leaves then turning gold. Unlike virus yellows mite damaged leaves are not brittle.
"We need to know what is happening in the main beet growing areas," says IACR Brooms Barn-based entomologist Alan Dewar. "The pest causes major damage to crops in Turkey, Greece and Chile, and in recent years there have been severe outbreaks in France and Belgium. With the trend to warmer summers in Britain it could become a more serious threat to UK sugar production."
Damage occurs when populations reach 2000-3000 mites/leaf.
• Concerned growers should contact IACR Brooms Barn (01284-812200).
REDSPIDERMITE
• Thrives in hot summers.
• Yield losses up to 30%.
• Turns red in autumn.
• Overwinters on weeds.