A new method to validate and compare varietal resistance and yield tolerance of sugar beet (Beta vulgaris) against the beet cyst nematode, Heterodera schachtii Schmidt

BACKGROUND: Beet cyst nematode, Heterodera schachtii Schmidt is a global threat to sugar beet crops, and is found in every major sugar beet growing region. Annual losses due to this nematode can be severe, being estimated at €90 m in Europe alone in the 1990s. Fortunately tolerant, resistant and partially resistant varieties have since been introduced which help to limit yield loss and are now widely being deployed in infested fields. However, understanding yield performance of these varieties has been difficult, especially when variety testing programmes usually require uninfested fields. RESULTS: For the first time, and in a standardised manner, we can now assess simultaneously the resistance of different varieties to BCN and their actual yield tolerance, by comparing them to varieties grown in uninfested micro‐plots alongside those which are infested. This method provides new insights on variety yield performance and nematode reproduction over an entire growing season. In addition, the investigations are also been able to detect significant physiological differences in the development and growth of the tolerant varieties' canopies and leaf chlorophyll levels. CONCLUSIONS: Our findings are of direct benefit to sugar beet growers challenged by BCN. The standardised testing provides new information on predicted variety performance. We found that these tests are justified, as not all tolerant varieties respond in the same manner to nematode infestation. Therefore, these assessments will become a vital part of variety testing for sugar beet growers, allowing for tailored deployment of variety types and more informed decision making on‐farm, helping to maximise yields whilst minimising nematode damage. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.