Arable
Climate change, volatility
and resilience EXPERT VIEW
This year is shaping up to be a high-bolting season for sugar beet, says Ian Munnery
T
he first flush of this season’s sugar beet bolters emerged in fields early last month, reflect- ing how low spring temperatures in- creased stress on plants.
This cold weather triggered plants to set seed as a ‘survival’ response – although the same low temperatures helped keep in check aphids and virus yellows. Even so, it means this is shap- ing up to be a higher bolting year than any of the past five seasons. This will be a pivotal factor in
choosing varieties for 2022 sowing (see graph). Bolters are the lesser of two evils compared to virus yellows because they can be managed to a cer- tain extent by selecting varieties with less tendency to bolt. Ultimately, everything will bolt to some extent if pushed hard enough. But bolting can be reduced by ensur- ing seed production tightly matches male and female flowering to prevent foreign pollen reaching female plants during seed production.
Significant potential The benefit is that early sowing can increase yield potential significantly – but only in suitable fields with soil types which warm more quickly. This allows plants to be sown earlier, in- tercepting more light and converting it into an extra 15–20% yield. But not all soil types or locations are suitable because you cannot con- trol what follows after sowing. Many French growers discovered this to their cost in spring 2021 when late frosts hit seedlings just as they emerged after early drilling.
Like any spring crop, plants should not be sitting shivering or emerging unevenly which can make timing of herbicide programmes difficult. This is why seeds are primed be- fore being pelleted, and why SESVan- derHave tests the commercial product used by growers – whether our own va-
30 ANGLIA FARMER • AUGUST 2021
rieties with our own seed technology – as successfully trialled for the past few years – or with Germains’ Xbeet priming.
Get early establishment right and there are many more benefits in ad- dition to increasing yield. An earlier, more even establishment, for exam- ple, can allow more timely use of her- bicides to control weeds. Critically, it also helps the plant
reach full plant maturity rapidly, which is important to limit the im- pact of virus yellows. SESVanderHave conducts exten- sive bolting trials across the UK beet growing areas. Commercial hybrids, such as Wren and Lacewing, have been selected exclusively for the UK as they bring lower early sown bolters than many pan-European varieties. As the UK experiences more ex- treme weather patterns and localised variation, there is merit in looking to your own farm experience when se- lecting varieties – and ultimately bal- ancing the need for greater resilience against potential reward.
Early indications of a minimum price proposal for 2022 given by Brit-
ish Sugar at this year’s Cereals event is positive news. Together with a contin- uation of the virus yellows assurance scheme, it provides some confidence for growers planning ahead.
Good prospects
While both the NFU and British Sugar are still to reach an agreement and bal- ance the risk and rewards for all par- ties, rising world sugar prices should buoy the prospects for beet – and con- fidence in the crop. Sugar prices are highly cyclic and world stocks are at a four-year low, so prospects look good for UK beet growers. While UK seasons vary, our mari-
time climate is more conducive to reli- able crop production than other parts of the world. Brazil, for example, had 40% less rainfall at a critical time this year – resulting in its lowest forecast yield for a decade.
Couple this with anticipated reduc- tions in sugar output this year from Australia, Thailand, Mexico and India – something which shouldn’t be lost on politicians who may be thinking they can rely on more imports at the cost of the domestic industry.
Seasonal summary of cold days (4-12ºC) Forty cold days – the threshold for bolting Low
temperatures are the most important element influencing bolting levels. This is why SESVanderHave maps field data with weather stations at each trials site.
Below:
Throughout all drilling windows, accumulated cold days are approaching or exceeding the 40 cold days milestone: good for virus yellow control, bad for bolters.
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