Are seed treatments effective against the same insects as below-ground traits?
Occasionally, there is confusion between the insects that are controlled with trait packages and the insects that are controlled by an insecticide seed treatment. Below-ground trait packages are only effective against corn rootworm larvae (northern, western, and Mexican) while above-ground trait packages are effective against several different species of caterpillars. Insecticides used with seed treatments provide control against several soil-dwelling insect pests as well as some above-ground pests early in the season.
What insects can current insecticide seed treatments control?
Depending on the specific insecticide class that has been applied to the seed, either a neonicotinoid (imidacloprid, clothianidin, and thiamethoxam) or a ryanoid (chlorantraniliprole) can control or suppress many common soil dwelling insect pests. Chlorantraniliprole is labeled for use at 0.25 mg active ingredient/kernel and 0.50 mg to 0.75 active ingredient/kernel. Clothianidin is labeled at three different rates of application, 0.25 mg active ingredient/kernel, 0.50 mg active ingredient/kernel, or 1.25 mg active ingredient/kernel. Both products are labeled for control of white grubs and wireworms. While chlorantraniliprole is labeled for suppression of corn seed maggot, clothianidin is labeled for control of this pest. However, chlorantraniliprole is labeled for armyworm control, while clothianidin is not. Chlorantraniliprole is labeled for cutworm control and clothianidin is specifically labeled for black cutworm control. The label of any insecticide seed treatment should be consulted prior to use to determine if the target pest is controlled.
What insects are controlled with seed treatments on Bayer corn products?
Table 1. Corn insects labeled for control or suppression with clothianidin or chlorantraniliprole and the rate of application.1
| Corn Insects Controlled with Clothianidin |
Rate of Application (mg of active ingredient per kernel) |
Corn flea beetle
Black cutworm
Seedcorn maggot
White grub (including European, Chafer larvae, May/June beetle larvae, Japanese beetle larvae) Wireworm
|
0.25 - 0.50 |
In addition to above,
Corn rootworm (including northern and western)
|
1.25 |
| Corn Insects Controlled with Chlorantraniliprole |
|
Cutworms
True Armyworm
Seedcorn maggot (suppression)
|
0.25 |
Wireworms
Larvae of Asiatic garden beetle, masked chafers, European chafer, Japanese beetle, May/June beetles
|
0.25 - 0.75 |
What insects are controlled with the SmartStax® RIB Complete®, VT Double PRO® RIB Complete®, and the Trecepta® RIB Complete® corn brand blend products?
Table 2. Corn insects labeled for control by trait package.2
| Corn Insects Controlled |
Trait Package |
Black cutworm
Corn earworm*
European corn borer
Fall armyworm
Corn rootworm larvae (including northern & western)
|
SmartStax® RIB Complete® Corn |
Corn earworm*
European corn borer
Fall armyworm
|
VT Double PRO® RIB Complete® Corn |
Black cutworm
Corn earworm*
European corn borer
Fall armyworm
Western bean cutworm
|
Trecepta® RIB Complete® Corn |
| *Cry1A.105 and Cry2Ab2 from B.t. controls or suppresses corn earworm.
|
Should resistance that has been documented to some of the B.t. proteins increase the reliance on seed treatments to help provide protection?
It depends on the species. Resistance to some B.t. proteins have been documented both in Canada and in the United States. In particular, the corn earworm (US and Ontario), European corn borer (Maritimes), Fall Armyworm (US), and western bean cutworm (US and Canada). This group of insects does not attack the corn seed or the plant early in the growing season, thus insecticide applied to the seed would not provide control in any event. However, black cutworm attacks the plant in the VE to V5 stage, and at this time there has not been documented B.t. resistance to this pest in Canada.
Corn rootworm resistance to some B.t. proteins has been documented in the US and Ontario and Quebec. Currently a higher rate (1.25 mg active ingredient/kernel) of neonicotinoid insecticides is being recommended to provide control in situations where the corn rootworm population is expected to be low or moderate.
Sources
1 Poncho® 600 FS Seed Treatment Insecticide label. Bayer CropScience. https://www.cropscience.bayer.ca/~/media/Bayer%20CropScience/Country-Canada-Internet/Products/Poncho/Poncho%20600FS%20label.ashx
2Baute, T. 2020. Canadian Bt corn trait tables with events and resistance status. The Ontario Ministry of Agriculture and Food. https://fieldcropnews.com/2020/10/revised-october-2020-canadian-bt-corn-trait-tables-with-events-and-resistance-status/.
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ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Performance may vary from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.
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