Performance of single-, dual-, and triple-component insecticide programs under moderate and severe sugarbeet root maggot pressure situations

Severe infestations of the sugarbeet root maggot (SBRM), Tetanops myopaeformis (Röder), occur on a frequent basis in central and northern portions of the Red River Valley (RRV) of North Dakota and Minnesota. Published research has demonstrated that this pest is capable of causing more than 45% yield losses in the absence of effective control measures (Boetel et al. 2010). High population levels of this pest often require aggressive management programs to ensure adequate protection of the sugarbeet crop. Control programs in areas at high risk of economic loss from this pest usually consist of either a granular insecticide or an insecticidal seed treatment at planting, followed by an additive postemergence insecticide application when the SBRM infestation warrants it. Broadcast applications of sprayable liquid insecticides, applied on an as-needed, rescue basis, are the most commonly used postemergence tools for SBRM control in the RRV. However, the use of postemergence granular insecticide products has increased in recent years. An advantage of postemergence sprays is that growers can use a “wait and see” approach, and make informed decisions on whether rescue insecticide treatments are needed based on current fly activity levels in their fields. This research was carried out to determine the most effective combinations of planting-time and postemergence insecticides to optimize sugarbeet root maggot control under both moderate and severe infestation levels.