Some popular insecticides won’t be available for use in field crops in Ontario in 2023. All products containing lambda-cyhalothrin including Matador, Warrior, Silencer, Labamba, Voliam Xpress and Endigo will be limited for use to only horticulture crops in eastern Canada this year.
The Pest Management Regulatory Agency (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. With no systems or mechanisms in place to ensure that treated field crops are not directly used for or diverted to become animal feed when bulk stored or downgraded, manufacturers have decided to limit the use of all lambda-cyhalothrin products to only horticulture crops in Eastern Canada in 2023.
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 overreliance of one product. Here are some of the options and management considerations for 2023:
Corn
Western bean cutworm – Although Matador and Voliam Xpress were important as rotational tools, Coragen, Delegate and Intrepid are also registered for WBC.
Other corn pests – Coragen is available for most of the other corn pests, though this product should only be applied a maximum of 4 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.
Soybeans
Bean leaf beetle – 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. 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.
Soybean aphids – Sefina, Sivanto Prime, Movento, Concept and Cygon/Lagon are available. Comparison trials with Sefina have shown more effective control and reduced impact to beneficials compared with Matador.
Cereals
Armyworm – Coragen and Delegate are both registered for armyworm on cereals.
Cereal leaf beetle – Although Malathion is the only product registered for cereal leaf beetle, Matador and Voliam Xpress were often used on CLB when other pests were also present. Spinetoram (Delegate in Canada) is registered for control of CLB in the US and could be a product to pursue registration for in Canada.
Alfalfa/Forages
Alfalfa weevil –Cygon/Lagon, Malathion and Coragen (suppression only) are registered for alfalfa weevil. Growers can best manage this pest by harvesting early when thresholds are reached and only rely on insecticides if the crop is not at bud stage yet or other factors that impede timely harvest.
Potato leafhopper – Silvanto Prime, Cygon/Lagon and Sefina (suppression only) are registered. Growers are encouraged to manage this pest by using potato leafhopper resistant varieties or cutting when thresholds are reached, before considering insecticide control.
Dry Beans
Western bean cutworm – Coragen and Intrepid are registered for WBC on dry beans, though this leaves only two products to rotate with, to reduce resistance risk.
Tarnished plant bug/lygus bugs – Though occasional pests, a few products are available for control including Beleaf, Cygon/Lagon and Decis. Applications of Cygon/Lagon or Decis should be avoided during bloom and should only applied in the late evening to reduce risk to pollinators.
Canola
Cabbage seedpod weevil – Limited treatment options are left so diligent monitoring will be key for this pest in 2023. Decis is registered but application during bloom should be avoided, which coincides with the is best timing to manage CSPW (10 to 20% bloom). Growers with a history of CSPW infestations or those with the most advanced fields (winter or spring) in the area should scout every 4 days, from bud stage until flowering is done. If thresholds are reached, an application of Decis must be made late in the evening(after 8 pm) to reduce the risk to pollinators.
Swede midge –Coragen and Decis are registered for swede midge on canola. Avoid applying Decis on a blooming crop, but if necessary, spray late in the evening (after 8 pm) to reduce the risk to pollinators. Reliance on only Coragen may increase the risk of resistance development in the absence of good rotational options.
There will be some adjustments needed to manage pests in 2023 as lambda-cyhalothrin products were the go-to for many of our field crop pests. Know which pests are your primary concern, determine if additional cultural practices like delayed planting, early harvest or using resistant varieties can reduce the risk where older chemistries are the only options available. Increase monitoring for high impact pests to reap the most benefits out of applications. Plan to apply the older chemistries in late evening if the crop is in bloom to reduce the risk to pollinators.
Resources:
PMRA’s Re-evaluation Decision Report on Lambda-cyhalothrin Products: https://www.canada.ca/en/health-canada/services/consumer-product-safety/reports-publications/pesticides-pest-management/decisions-updates/reevaluation-decision/2021/lambda-cyhalothrin.html
OMAFRA Crop Protection Hub for all Registered Products (Replaces Field Crop Protection Guide): https://cropprotectionhub.omafra.gov.on.ca/
Stay Informed on Twitter and Field Crop News for current pest alerts and specific management guidance: https://fieldcropnews.com/ and https://twitter.com/TraceyBaute