New genetics could offer growers solution to Cercospora threat

Problem disease can halve sugar beet yields

Latest breeding developments could offer growers a new level of protection against the increasing threat of Cercospora to sugar beet crops.

Cercospora Leaf Spot to give it its full name, is caused by the fungus Cercospora beticola and has been shown to reduce sugar beet yields by up to 50% – and it is increasingly prevalent.

“Warmer summer days with morning dews provide particularly suitable conditions for the disease to start developing,” says KWS sugar beet product manager Martin Brown.

“It’s a disease that thrives in prolonged warm and wet conditions, so the type of variable growing conditions we are increasingly seeing as a result of climate change suit it perfectly.

“The condition can cause significant levels of defoliation in years such as 2020, causing rapid leaf loss from plants with production implications to significant areas of the UK crop.

Canopy growth

“Damaged sugar beet responds by using its own reserves of sugar to encourage new canopy growth which results in the significant yield losses seen.”

The first UK variety to feature new CR+ Cercospora protection, Chyma KWS has attracted significant interest in its launch year. Its high treated and untreated yields has also earned it a place on the 2026 Recommended List of seed varieties.

“By any standards, Chyma KWS is a hugely attractive variety combining top yields, high sugar content and excellent disease protection including built-in Cercospora protection against this devastating disease.

“It has excellent yields of 99.4% adjusted tonnes on the new Recommended List and a sugar content of 16.6%. With an eye-catching untreated yield of 103% as a result of its exemplary disease protection, it is the cleanest variety growers can choose for a second year running.”

The sum of its ratings for rust, powdery mildew and Cercospora are amonge the highest seen in RL trials at 21.4 out of a possible 27. With no obvious weakness in its leaf disease scores, Mr Brown says Chyma KWS is a great option for later lifting, too.

“Achieving that level of yield with such a strong agronomic package is a real achievement for a variety with a trait new to the market.

“Often with beet varieties the introduction of new traits has meant these ‘novel varieties’ are not on par with the elites and have a significant yield lag, however Chyma KWS bucks this trend.”

Disease development slowed

With CR+, the disease progression is delayed, Cercospora appears later in the season minimising green leaf loss and thus reducing the impact of the disease, explains Mr Brown.

“Chyma KWS offers growers a tremendous disease package and excellent Cercospora tolerance, but to maximise performance on farm the variety should still be grown with fungicides.

“The need to spray will be lower however on a CR+ variety but still having a fungicide programme helps to protect yields and manage any potential development of Cercospora in the canopy.”

The first fungicide is the most important. But other foliar beet diseases will still need to be controlled, says Mr Brown. And replicated trials from 2023 and 2024 focused on utilising the performance of Chyma KWS in different situations.

“The trials provided different disease scenarios and fungicide programmes, highlighting the benefits of using fungicides with the cleanest variety available.

“Yield responses from across all the treatments with fungicides in the two seasons showed an impressive average benefit of 8.3 adjusted t/ha. With current sugar beet prices this gives a margin increase of £275/ha.”

Ideal later drilling choice

Chyma KWS is suitable for sowing from mid-March, given its strong disease package, and observations from UK trials show it is a variety that can suit later drilling and harvesting in the campaign, he explains.

“If you’re wanting to maximise yield and leave the crop as long as possible before lifting, then Chyma KWS is a great choice.

“It could be that you’re planning on using a later drilling wheat like KWS Extase or you’re on a parcel of land that you don’t want to get on to until the following February, for example.

“In such cases a variety with good disease resistance should be chosen and if you’re leaving the crop in the ground over winter, one with good canopy protection is essential.

“Chyma KWS therefore makes a great later drilling choice with its CR+ Cercospora tolerance adding to its appeal.”