By Blake Jackson
Recent field evaluations of canola in western Kentucky revealed widespread infestations of turnip aphid (also known as mustard aphid) across multiple counties, including Graves, Marshall, and Caldwell. Observations were made by Felipe C. Batista, UK Entomology Postdoctoral Scholar.
The outbreak appears to be linked to unusually dry spring conditions, with below-average rainfall across the region.
Drought stress can make canola plants more vulnerable to sap-feeding insects because it increases free amino acids in plant sap, improving its nutritional value for aphids.
Three aphid species are commonly found in canola fields: turnip aphid (Lipaphis erysimi), green peach aphid (Myzus persicae), and cabbage aphid (Brevicoryne brassicae). Each species can be identified by distinct characteristics and feeding locations on the plant.
Green peach aphids are pale green and often found scattered on the underside of leaves. Cabbage aphids are darker, covered in a waxy coating, and tend to form dense clusters on upper leaves and flower clusters. Turnip aphids are smaller, dark green, and usually concentrated on racemes.
Scouting is essential for managing infestations. Farmers are advised to inspect multiple areas of the field and estimate the percentage of plants infested.
Action is recommended when approximately 20% of plants host colonies of 25 or more aphids. If populations remain below this threshold, continued monitoring is advised rather than immediate treatment.
Natural enemies such as lady beetles, syrphid fly larvae, and parasitic wasps were frequently observed and play an important role in controlling aphid populations. These beneficial insects can help reduce the need for chemical control.
If treatment becomes necessary, selective insecticides containing flonicamid or sulfoxaflor are recommended to minimize harm to beneficial insects.
Producers should always follow label instructions and consult local extension specialists before applying any control measures.
Photo Credit: pexels-timm-stein
Categories: Kentucky, Crops