Canada approves Diflufenican, SC500, SC600, and SC617

Registration decision statement for Diflufenican, SC500, SC600, and SC617

Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the Pest Control Products Act, is granting registration for the sale and use of Diflufenican Technical and SC500 containing the technical grade active ingredient diflufenican, for pre-plant and pre-emergent weed control in corn and soybean; SC600, containing the technical grade active ingredients diflufenican and metribuzin for pre-plant and pre-emergent weed control in soybean; and SC617 containing the technical grade active ingredients diflufenican and isoxaflutole for pre-plant and pre-emergent weed control in field corn.

The Proposed Registration Decision PRD2023-07, Diflufenican, SC500, SC600, and SC617, containing the detailed evaluation of the information submitted in support of this registration, underwent a 45-day consultation period ending on 17 September 2023. The evaluation found that, under the approved conditions of use, the health and environmental risks and the value of the pest control product(s) are acceptable. Health Canada received written comments relating to the health risk assessment during the public consultation period conducted in accordance with section 28 of the Pest Control Products Act. The written comments were from a private citizen and the registrant.

What is diflufenican?

Diflufenican is a herbicide that inhibits synthesis of phytoene desaturase, which causes degradation of chlorophyll and destruction of chloroplast membranes responsible in carotenoid production. Sensitive plants develop symptoms of stunting, discolouration, and necrosis, leading to plant death.

What is the value of SC500 Herbicide, SC600 Herbicide, and SC617 Herbicide?

SC500 Herbicide provides early-season and season-long residual control of Amaranthus species, which are problematic and highly resistant to many herbicide modes of action in corn (field and seed) and soybean. SC600 Herbicide and SC617 Herbicide, co-formulations of diflufenican with other registered herbicides, control a broader spectrum of weeds with soil residual activity and also aim to manage existing and the future evolution of herbicide resistant weeds in corn (field and seed) and soybean.

SC500 Herbicide is formulated with diflufenican for pre-plant surface and pre-emergent application to corn (field and seed) and soybean. It provides early-season control of redroot pigweed, green pigweed, tall waterhemp, and palmer amaranth, including biotypes resistant to many herbicide modes of action, at 120–180 mL/ha and season-long control of these weeds at 180–360 mL/ha.

SC600 Herbicide is a co-formulation of diflufenican with metribuzin for pre-plant surface and pre-emergent application to soybean. It provides early-season or season-long control of weeds controlled by SC500 Herbicide and weeds controlled by registered metribuzin-based herbicides, applied at similar active ingredient rates.

SC617 Herbicide is a co-formulation of diflufenican with isoxaflutole for pre-plant surface and pre-emergent application to corn (field and seed) in Eastern Canada and British Columbia. It provides early-season or season-long control of weeds controlled by SC500 Herbicide and weeds controlled by registered isoxaflutole-based herbicides, applied at similar active ingredient rates.

Registrations of these herbicides provide users with options for pre-plant or pre-emergent residual control of broadleaf weeds, including Amaranthus species that are problematic and highly resistant to many herbicide modes of action, in corn (field and seed) and/or soybean. The application of these herbicides reduces early-season weed competition to the emerging crop allowing the crop to benefit from additional moisture, nutrients, and light that would otherwise be captured by the weeds. Weed management at this time is critical as the crop does not compete well with weeds until crop canopy closure. As all three end-use products have soil residual activity, the reduction in weed competition with the crop is extended.