Aphid samples confirm presence of virus
More than 100 flying aphids were detected in the first week of sampling this sea- son, says the British Beet Re- search Organisation. Maps showing week- ly aphid flight pressure are published by the BBRO from mid-April to July. They show where flying aphids (
M.per- sicae ) are being detected. In week one, researchers iden- tified 104 flying aphids from received samples.
The spray threshold is one green wingless aphid per four plants “
We don’t want secondary spread of virus within the crop
of virus within the crop, especial- ly at early growth stages when vi- rus yellows’ impact on yield is at its greatest.”
Resistance management is im- portant too, adds Dr Stevens. “The emergency authorisation states that Biscaya should be used in alternation with insecticides of a different mode of action. Ideal- ly we would want no insecticide applications but we may need three.” To comply with the emergen-
cy authorisation and IRAC re- sistance management guidelines,
Biscaya should be used first. If further applications are needed, Dr Stevens says growers should follow with Teppeki (flonicamid) then switch back to Biscaya. In addition to yellow wa-
ter-pan catches, the BBRO inter- active map will show the results of BBRO testing for the yellowing viruses carried by these aphids. The map is at
www.bbro.co.uk/ on-farm/aphid-survey-map/
The maps highlight where growers should remain extra vigilant to reduce the risk of virus yellows. In the early re- sults, the presence of mild yel- lowing virus was detected in samples from Milton, Cam- bridgeshire; and Bawtry, Don- caster.
Samples are updated on
Monday and Thursday each week. Aphid pressure is mapped weekly and cumu- latively as the season pro- gresses. Growers should in- spect growing crops regularly and use aphicide sprays when threshold populations are de- tected.
Recommended list includes first herbicide-tolerant variety
The BBRO Recommended List for 2020 includes the first of a new generation of varieties tolerant to ALS herbicides. Smart Janninka KWS has been developed for use in the for use in the Conviso Smart system developed by agrochemical giant Bayer and plant breeder KWS to reduce the number of sprays need- ed to keep crops weed-free. Smart KWS seed is a hybrid variety developed by KWS car- rying specific tolerance to the ALS-inhibitor based herbicide Conviso One – a broadleaf- and grass weed herbicide developed by Bayer based on active ingredi- ents from the ALS-inhibitor class. KWS and Bayer have described the Conviso Smart system as “the door opener for a new weed control
with the Smart KWS seed have been approved and are expected to be available for the 2020 sowings. Bayer says its broad range her- bicide delivers high performance even in situations with hard-to- fight weeds.
When to sow Smart Janninka
will be a decision best taken by growers in consultation with their advisers. But KWS says growers can be confident that yields will be close to that of some established varieties where it is considered suitable.
strategy” in sugar beet. KWS says its herbicide tolerant beet varie- ties provides growers with more flexible options. Classically bred, Smart Jan-
ninka has a naturally occurring change in an enzyme involved in
the biosynthesis of essential ami- no acids. The Conviso One herbi- cide cannot bind to this enzyme which means the sugar beet plant continues to grow while weeds around are killed.
Conviso One herbicides for use
“When grown using the dedi- cated herbicide, Smart Janninka KWS yields close to that of some established varieties on the Rec- ommended List,” says Ben Bish- op, KWS sugar beet country man- ager for the UK.”
JUNE 2019 • ANGLIA FARMER 63
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