Warm, sunny days are upon us and planting
is in full swing, but a recent re-evaluation of linuron by Health Canada has been
cause for concern as things ramp up, especially for carrot growers. While some
uses of linuron have been cancelled, continued use has been approved for
carrots, parsnips, potatoes, asparagus, and shelterbelts. Unfortunately, the
re-evaluation interrupted production schedules, resulting in shortages of a
popular Group 7 herbicide that many growers rely on for weed control.
In response to this situation, the Pest
Management Regulatory Agency (PMRA) has approved an Emergency Use Registration
(EUR) for Tough 600 EC herbicide in carrots, valid in several Canadian
provinces, including Nova Scotia. Additionally, Ultra Blazer herbicide has
received a User Requested Minor Use Label Expansion (URMULE) for use in
carrots.
Ultra Blazer herbicide (acifluorfen) is a Group 14 herbicide approved for use in carrots
to suppress redroot pigweed. This post-emergence herbicide works mainly by
contact action and rainfall within 6 hours of application will reduce
effectiveness. Cool weather or drought will delay herbicide activity. Contamination
of groundwater may occur if this chemical is used in areas where soils are
permeable (ex. sandy soil) and/or if the water table is shallow.
Tough 600 EC herbicide (pyridate) is a Group 6 herbicide approved for use in carrots
between May 1, 2022 to December 31, 2022. This post-emergence herbicide is
already approved for weed management in a variety of crops across Canada and
carrots have shown tolerance in development trials. Not all carrot varieties
have been tested, so it is recommended to test in a small area of the field
first.
|
|
Tough 600 EC herbicide |
Ultra Blazer herbicide |
|
Active ingredient |
Pyridate |
Acifluorfen |
|
Registration period |
May 1-Dec 31 2022 |
|
|
Group |
6 |
14 |
|
Weed control |
Post-emergent control of broadleaf weeds - redroot pigweed, common
lamb’s quarters, false cleavers, black nightshade |
Post-emergent suppression of redroot pigweed |
|
Application rate |
0.5 - 0.75 L/ha (use high rate when weed pressure is high or for
harder to control weeds) |
94 mL/ha with 0.5% v/v Assist Oil Concentrate |
|
Applications per season |
1 |
1 |
|
Application Timing |
Apply to carrots in the 2 to 7 leaf stage that have sufficiently
hardened off and have a waxy cuticle; apply to young, actively growing weeds |
Apply after carrots have emerged and pigweed is in the 2 to 4 leaf
stage |
|
REI |
12 hr |
12 hr |
|
PHI |
60 days |
40 days |
|
|
Do not apply either product to crops under stress. |
|
Additional notes regarding use of Tough 600 EC herbicide:
Do not apply when the temperature is
greater than 25oC (may cause crop injury). Application of this
product is not recommended when temperatures will fluctuate more than 10oC
in a 24-hour period, due to increased risk of crop injury.
Avoid irrigating for three days prior to
herbicide application.
Delay application for three days after
rain, cool, or cloudy weather to allow the crop to harden off.
Treated carrots may show signs of stunting,
chlorosis, and/or partial defoliation of leaves present at the time of
application, but the carrots typically outgrow these symptoms, with no adverse
effects on crop vigour, maturity, or yield.
Tough 600 EC
Herbicide offers contact control of susceptible species and has no residual
activity. Crops rotated following the use of Tough 600 EC Herbicide should not
be negatively impacted
For more information on these products, consult the label (see links below) or contact
your local crop specialist or a representative from the chemical supplier.
Ultra Blazer herbicide - Label
Tough 600 EC herbicide - Label
Pesticide Label Search -
Health Canada (hc-sc.gc.ca)