After five years of environmental risk assessments, the Pest Management Regulatory Agency (PMRA) says that Canadian growers will be able to use clothianidin and thiamethoxam for some key uses with additional risk mitigation measures.  

 

“Most of the critical uses are being retained,” says Chris Duyvelshoff, crop protection advisor, Ontario Fruit and Vegetable Growers’ Association. “This is a huge improvement from complete cancellation.” 

 

Growers will be relieved to see the following key uses will be acceptable for continued registration.  

 

Key uses for clothianidin (Titan/Sepresto/Clutch): 

 

Potato seed piece treatment

 

Most vegetable seed treatments including dry bulb onion

 

Key uses for thiamethoxam (Cruiser/Actara/Minecto Duo):

 

Potato seed piece treatment

 

All vegetable seed treatments including cucurbits

 

Foliar use for weevils on strawberry and pepper (field and greenhouse)

 

That said, in-furrow application of clothianidin on potatoes and seed treatment for field-sown leafy vegetables and bunching onions is cancelled. In the case of thiamethoxam, its use in potatoes is also cancelled for soil drench application. Foliar application on lowbush blueberries is cancelled. 

 

The active ingredients of these neonicotinoids, along with imidacloprid, have been under review since 2016. These decision documents are addressing a special concern with regards to aquatic insects. They will be incorporated into final decisions for both products due in 2022. A separate decision on imidacloprid is yet to come. 

 

The new regulations for clothianidin are as follows:

 

-  The maximum seed treatment rate for field corn is reduced to 150 g a.i./100 kg seed. This results in the cancellation of the use for corn rootworm. No change is required for popcorn or sweet corn.

 

-  For seed treatment uses on vegetables, the yearly maximum rate per hectare is limited to 100 g a.i./ha. This limits the planting rates used on broccoli, bulb onion, carrot, cabbage, cucumber and leek to meet this yearly maximum rate.

 

-  The maximum foliar rate for use on cucurbits is reduced to a single application of 70 g a.i./ha per season. This results in the cancellation of use for brown marmorated stink bug.

 

-  The maximum foliar rate for use on potatoes is reduced to a single application of 52.5 g a.i./ha per season.

 

-  The maximum foliar rate for use on turf is reduced to a single application of 125 g a.i./ha per season. This results in the cancellation of use for hairy chinch bug, annual bluegrass weevil, bluegrass billbug and European crane fly.

 

-  Cancellation of greenhouse seed treatment use for onion maggot and seed corn maggot on bulb onions, as these are only pests found in field production.

 

-  New or revised spray buffer zones are required for freshwater habitats.

 

The new regulations for thiamethoxam are as follows: 

 

-  The maximum seed treatment rate for field corn (including seed corn production) is reduced to 200 g a.i./100 kg seed. This will result in the cancellation of the use for planting in Canada for corn rootworm (including for seed corn production). No change is required for popcorn or sweet corn.

 

-  The maximum seed treatment rate for soybean is reduced to 30 g a.i./100 kg seed. This will result in the cancellation of the use for bean leaf beetle, European chafer, soybean aphid, and wireworm.

 

-  The maximum soil drench and in-furrow rate for leafy vegetables is reduced to 90 g a.i./ha. This will result in the cancellation of the use for cabbage looper, beet armyworm, corn earworm and fall armyworm.

 

-  The maximum soil drench and in-furrow rate for brassica vegetables is reduced to 90 g a.i./ha. This will result in the cancellation of the use for dipteran leafminers, cabbage looper, diamondback moth, imported cabbageworm, thrips, beet armyworm, corn earworm, fall armyworm, and yellowstriped armyworm.

 

-  The number of foliar applications is reduced to one per year on dry shelled bean, potato, soybean.

 

-  The number of foliar applications is reduced to one per year for the following vegetables and listed pests: all pests on celeriac and for pepper weevil on peppers. In the case of fruiting vegetables, for stink bug, tarnished plant bug and brown marmorated stink bug the number of applications at the highest application rate (52.5 g a.i./ha) is reduced to one per year.

 

-  The number of foliar applications is reduced to one per year on cranberry. There is also a requirement to hold flood water for 30 days for cranberries that require flooding.

 

-  New or revised spray buffer zones are required for freshwater and terrestrial habitats.

 

For the PMRA decision on clothianidin, link here: https://bit.ly/3sJL1wb

 

For the PMRA decision on thiamethoxam, link here: https://bit.ly/3fx5qAY

 

 

Source:  Pest Management Regulatory Agency March 31, 2021 decision