Carrot herbicides

 

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 25^oC (may cause crop injury). Application of this product is not recommended when temperatures will fluctuate more than 10^oC 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)

 

Wireworms in Nova Scotia

Wireworms in transplants

For those of you who missed Dr. Christine Noronha's presentation on wireworms last week, you can find her presentation here. 

While many areas in Nova Scotia thankfully do not report wireworm problems, there are definitely high populations in some fields.  Last spring, we set traps in a few fields around the province.  Below is a graph from a vegetable field in Colchester County, showing high numbers of Agriotes sputator, one of the more voracious click beetle (adult wireworm) species.  Click beetle flight happens earlier in the warmer parts of the province such as the Valley.

Click beetle catch in Colchester County, 2016.

Perennia has set out some click beetle pheromone traps again this year, and we just collected our first sample.  Below is a photo of our first "haul" from Annapolis County.  On the left is A. obscurus, the middle is A. sputator, and on the right is A. lineatus.  Pheromone traps only attract males, so do not reduce the click beetle/wireworm population, but do give us a good idea of pest levels.  

May 23, 2017 click beetle catch from Annapolis County.

Wireworm updates

Dr. Christine Noronha is an entomologist with Agriculture and Agri-Food Canada in PEI with a particular interest in wireworms.  She will be visiting Nova Scotia this week and will give an overview of wireworms and their lifecycle (similar to last year’s presentation), as well as the most recent updates and highlights from her research into this pest. 

The presentation will take place at the Kentville Research Station (32 Main Street, Kentville) on Friday, May 12^th, 2017 at 9 am in the Perennia Training Room.  I know it’s a busy time of year, but we hope you can join us! 

Carrot Pest Activity

Ontario has a Carrot Pest Activity Calendar, which is a great resource to help you predict when pests might start to become a problem. You can find the full calendar here: https://onvegetables.files.wordpress.com/2017/04/carrot-pest-activity-calendar.pdf  As the calendar is based on Ontario dates, there will be slight variation for Nova Scotia conditions, but it's well worth a read! 

Insect and Floating Row Covers

Insect covers provide an alternative pest control option for growers.  Insect covers come in different sizes and are suitable for control of a whole host of insects such as carrot rust fly, cabbage maggot, and flea beetles.   Insect covers will create a physical barrier between the crop and flying insects.  It has to be applied tightly so insects are unable to get under the netting.

 

Insect cover on rutabaga

 

Insect covers do not trap heat and therefore are used on cole crops, carrots etc where extra heat might be undesirable.  On the other hand crops such as cucurbits, lettuce and peppers may benefit from extra heat, so floating row covers are more beneficial.

 

Floating row cover on lettuce