Rising aphid populations threaten sugarbeet yield and sugar quality
Sugarbeet root aphid populations have risen significantly across Michigan's sugarbeet-growing region in recent years, creating new challenges for farmers. These pests feed on the secondary roots of sugarbeet plants, reducing their ability to absorb water and nutrients effectively.
As a result, growers may experience lower yields, reduced sugar content, decreased recoverable sugar, and poor storage quality after harvest.
The sugarbeet root aphid reproduces rapidly because all individuals are female and can give birth to live young without mating. Several generations can develop within a single growing season, allowing populations to increase quickly under favorable conditions.
One of the most common signs of a severe infestation is a wilted canopy that appears in circular patches throughout a field. When affected plants are examined, growers can often find yellow-green aphids along with distinctive white waxy material around the roots. This wax helps protect the insects from moisture and physical damage in the soil.
After harvest, sugarbeet root aphids survive the winter on sugarbeets left in the ground and on related weeds belonging to the amaranth family. Common lambsquarters and redroot pigweed serve as alternate hosts that help sustain aphid populations between growing seasons. Maintaining strong weed control throughout the crop rotation can reduce these survival sites and lower future infestations.
Plant resistance remains one of the most important tools for managing sugarbeet root aphids. Sugarbeet breeding programs regularly evaluate and develop varieties with improved resistance to the pest.
In situations where resistance alone is insufficient or during severe outbreaks, growers may consider systemic insecticides such as spirotetramat, the active ingredient found in Boxadon 360 SC and Movento.
During the 2026 growing season, researchers from Michigan State University established replicated field trials to compare standard seed treatments with additional spirotetramat applications later in the season.
These studies are evaluating the impact on both yield and sugar content while also examining the value of rescue treatments in heavily infested fields.
Natural enemies also contribute to aphid management. Larvae of the chloropid fly Thaumatomyia glabra feed on root aphids underground.
Beneficial fungi further assist by infecting aphids, causing them to die and release spores that can spread to other aphids and remain in the soil for future control.
Although biological controls provide valuable support, they are often unable to suppress populations during major outbreaks.
The unusually high infestations observed during the 2025 and 2026 growing seasons have raised concerns among researchers and industry leaders. Extended periods of hot, dry weather during July and August may have encouraged rapid population growth.
Other possible factors include changes in weed host populations or shifts in the effectiveness of resistant sugarbeet varieties.
To better understand these trends, sugarbeet seed companies, Michigan Sugar Company, Michigan State University Extension, and the USDA-East Lansing are conducting monitoring programs and research trials.
Their efforts aim to identify the causes behind these increasing outbreaks and develop effective strategies to protect sugarbeet production in the future.
Photo Credit: Pexels – Jean de Roy