Navigating lambda-cy restrictions — 2023 insect control options for corn, soy and cereals

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The Pest Management Regulatory Agency’s decision to restrict the use of lambda-cyhalothrin products for the 2023 growing season could have a significant impact on how growers manage corn, soybean and cereal crops this season.

Lambda-cyhalothrin, the active ingredient in some the most commonly used insecticides growers use to control yield-robbing pests such as soybean aphids and western bean cutworm, will be impacted by a label change that eliminates their application on crops or crop by-products that end up as feed. The new label comes into effect April 1, 2023.

The PMRA has asked crop protection companies to modify their labels to reflect the restricted use. Some companies have opted to remove key products from certain markets instead.

What does that mean for corn, soy and wheat producers? In this video report RealAgriculture’s Bernard Tobin asked Ontario Ministry of Agriculture, Food and Rural Affairs field crops entomologist Tracey Baute to identify restricted products, review management implications, and share insect control options for growers. (Story continues after the video.)

The PMRA re-evaluated lambda-cyhalothrin and end use products in 2021 and determined that some uses posed human health risks, particularly in animal feed uses, as well as in lettuce, mustard seed (condiment type), bulb vegetables, and oilseeds (except flax seed, mustard seed (oilseed-type) and canola). These uses are to be halted by April 2023.

See Related: ADAMA Canada moves forward with lambda-cy sales for 2023

Baute published a full review of how the decision impacts a full range of crops on the Field Crop News website. In the interview she notes that, in most cases, there are other products available to manage key field crop pests. But there are a few situations that will require the use of older chemistries or will lack good rotation products to reduce the risk of resistance from over-reliance of one product.

When it comes to a corn pest like western bean cutworm, Baute says that although Matador and Voliam Xpress — now restricted — were important as rotational tools, Coragen, Delegate and Intrepid are also registered to control the pest.

Baute says Coragen is available for control of most of the other corn pests, but she notes that “this product should only be applied a maximum of four times per season, so choose wisely which pest to focus this product for.” Older pyrethroids like deltamethrin, and cypermethrin are registered, though application during pollination should be avoided to reduce risk to pollinators.

In soybeans, bean leaf beetle could prove challenging. Baute says “mild winters, like this one, increases the risk of this early season pest. Options are limited to dimethoate (Cygon/Lagon) or Concept (suppression only) so it’s best to reduce your risk of early season infestations,” she adds.  “This includes adjusting planting dates, to avoid the field being the first to emerge in the area (most attractive), use insecticide seed treatment if you have a history of early season injury and scout for pod feeding weekly starting in R2 stage in food grade/IP soybeans to ensure a timely insecticide application is made to protect quality.” Dimethoate cannot be applied within 30 days of harvest, she notes.

In the video, Baute offers tips on how growers can best tackle soybean aphids, with use of the commonly-used Matador now restricted. She also discusses cereals and what options growers have for controlling pests like armyworm and cereal leaf beetle.

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