Lessons learned from the 2020 beet season – Farmers Guardian – Darryl Shailes
As the end of the 2020/21 sugar beet campaign nears, Darryl Shailes looks at what last year’s challenges taught us for managing risks in the new crop ...
Maximising establishment
The wet winter of 2019/20 followed by a very dry spring created a huge challenge for establishing crops on better bodied soils last spring, with some fields not making full canopy until well into July.
Mr Shailes says: “In the worst affected areas, establishment was down 35 per cent across areas of fields until the rains came and filled in the gaps, but by then the yield potential was already reduced significantly.
“In some fields this very poor establishment was the main cause of low yields. We have seen from the Beet Yield Challenge that good early establishment is one of the main drivers of high yields.”
The weather is beyond growers’ control, so the focus must be on improving the health and resilience of soils to better withstand very wet or dry spells, thereby helping to optimise establishment.
The Beet Yield Challenge shows beet crops generally perform better after over-winter cover crops, organic amendments or incorporated straw.
When using cover crops in future seasons, Mr Shailes advises growers to tailor mixes to conditions and ensure they manage any potential risks, such as free living nematodes, beet cyst nematode or aphids overwintering on the cover.
Darryl Shailes, Hutchinsons root crop technical manager
Early weed control
The loss of desmedipham is a big blow for weed control in sugar beet, especially as alternative products generally lack the same efficacy in more challenging conditions, My Shailes says.
Targeting weeds early at the cotyledon stage is key to effective control and minuses potential yield losses from crop competition. However, last spring showed how difficult this can be in practice when very dry conditions hinder the efficacy of residual chemistry, and weeds are able to grow away in gappy crops.
Controlling larger weeds such as fat hen will be ‘virtually impossible’ in certain conditions, so growers must focus on using robust residuals and pre-emergence treatments this spring and target smaller weeds post-emergence, Mr Shailes says.
He suggests products based on ethofumesate + metamitron, or quinmerac + metamitron, with ethofumesate added where grass-weeds are a concern.
Post-emergence, where brassica weeds and polygonums are a problem, then lenacil + triflusulfuron is likely to be needed.
“Targeting smaller weeds is likely to take more agronomist involvement and increase the number of applications and cost for growers,” Mr Shailes adds.
Mitigating virus risk
Virus yellows was a massive issue last season as many young crops were hit by a very early influx of high numbers of virus-transmitting aphids. With no protection from neonicotinoid seed treatments, the timing of foliar sprays was critical, but even these only offered limited protection given the sheer number of aphids in many areas.
“This was made doubly difficult when trying to time a limited number of products to fields only partially emerged,” says Mr Shailes.
“The threshold of one green wingless aphid per four plants was blown into insignificance with some areas recording up to 30 wingless green aphids/plant. No doubt some will have seen more.
“With the amount of virus new in the wild beet populations, virus risk has the potential to be high again, but will depend greatly on the winter weather.”
Considerations
The Emergency Authorisation of thiamethoxam seed treatment for the 2021 crop means there will also be rotational considerations to be made with regards to flowering crops, if treated seed is grown. Crops that receive a seed treatment will still need close monitoring if risk is high however, and the timing of any post-emergence treatment will need to be very accurate, he adds.
Managing cercospora
Cercospora was another significant challenge in some crops last year, as high temperatures combined with rain and humidity during August and early September favoured disease development.
Mr Shailes says: “In recent seasons we have had the temperatures but not the rain, so for many this was their first encounter with cercospora, and fungicide strategies that concentrated on rust and mildew were found wanting, allowing disease to spread rapidly.
“The current available chemistry based on strobilurins and triazoles are only partially effective against cercospora but hopefully there will be some new actives available soon,” he adds.
Intervals
“Sugar beet disease control will mean more applications with shortened intervals in the weather is suitable for cercospora in 2021.”
He also advises growers to look out for industry guidance this spring or varietal susceptibility to cercospora and virus to aid decision making in the coming season.
Email Us