Reducing aphid infestation by growing barley as a companion plant in sugar beet cultivation

Controlling virus yellows in sugar beet is one of the current challenges due to the reduction of available insecticides and rising aphid resistance. This study evaluated the use of barley as a companion plant to reduce aphid infestation and associated virus yellows in sugar beet across 18 field sites in four European countries (2021–2023). Barley co-cropping significantly reduced populations of winged and wingless Aphis fabae and wingless Myzus persicae, key vectors of virus yellows. At sites with artificially introduced viruliferous aphids, barley presence led to a statistically significant reduction in virus yellows symptoms. Natural infection sites showed overall fewer and site varying degrees of virus infection and over all sites no significant reduction of virus yellows symptoms by barley. However, companion planting also resulted in reduced sugar yield. Therefore, potential yield loss due to virus infestation needs to be balanced with losses incurred by embracing a new cropping system with barley.