Vigilance still required as cold weather slows both sugar beet growth and aphid migration

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Despite the unseasonably cold weather continuing across much of the UK, sugar beet growers must continue to monitor aphid migration closely to best protect crops until they reach the critical 12-leaf growth stage says independent agronomist Matt Hardy of Farmacy PLC.

Mr Hardy, who annually advises on 400ha of sugar beet across Norfolk and north Suffolk, confirms that the persistent Spring cold spell has been both a blessing and a curse for many sugar beet farmers.

“Colder weather has definitely delayed aphid migration into crops but it has also simultaneously slowed up growth rates with many crops not yet at 12 true leaves. Although the recent emergency authorisation of acetamiprid is positive news, programmes must start with flonicamid, available as Teppeki in the UK, followed up with acetamiprid if and when required.

“Teppeki supresses aphid feeding within 1 hour of application and, if the timing of aphid activity ties in with a weed control spray, can be tank-mixed alongside a herbicide application to reduce crop passes. However, given the importance of application timing once the aphid threshold has been reached, I would certainly advise not compromising effective control for the sake of an additional sprayer pass.

“Teppeki has local systemic and translaminar activity and a good safety profile with respect to beneficial insects. Up to 21 days persistence in the leaves present at application is also a useful trait if there is a prolonged period of aphid activity. For best results it must be applied at the full rate of 140g/ha in minimum water volumes of 200l/ha to ensure the right level of coverage” he adds.

On crop monitoring Matt advises a 7 day check with the flexibility to come down to 3 or 4 day intervals if temperatures begin to rise.

“The BBRO’s yellow water pan trap network is an excellent barometer for aphid activity on a national scale but I’d also advise growers in localised areas to set up a WhatsApp group in order to update each other regularly. Aphids tend to move at the same time within the same area so, if a neighbouring grower reports that they have reached the key threshold of 1 green wingless aphid per 4 plants, it’s often likely that aphids have moved into other localised crops as well. Extra vigilance and the ability to react quickly when threshold is reached are the keys” he concludes.



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