Category Archives: Weed Management

Re-cropping after Callisto or Command?

Kristen Obeid, OMAFRA Weed Specialist – Horticulture

Callisto and Command are relatively new herbicides to various horticulture crops in Ontario.  They both cause bleaching symptoms even though Callisto is a Group 27 herbicide and Command is a Group 13.  Group 27 and Group 13 herbicides are categorized as carotenoid biosynthesis inhibitors.  Group 27 herbicides are also frequently referred to as HPPD inhibitors.  This refers to the inhibition of p-hydroxyphenyl pyruvate dioxygenase (HPPD).  The  inhibition of HPPD gives rise to bleaching symptoms on new growth.

Command
Command injury on tomato due to drift.

Continue reading Re-cropping after Callisto or Command?

OMAFRA IPM SCOUT TRAINING WORKSHOPS FOR 2018

These workshops are available for those who will be scouting horticultural crops this year.

To register, please contact OMAFRA’s Agricultural Information Contact Centre at 1-877-424-1300. Continue reading OMAFRA IPM SCOUT TRAINING WORKSHOPS FOR 2018

Notice of minor use label expansion registration – Prowl H2O herbicide for cabbage, broccoli and cauliflower

Jim Chaput, Minor Use Coordinator

The Pest Management Regulatory Agency (PMRA) recently announced the approval of a minor use label expansion registration for Prowl® H2O Herbicide for control of labeled weeds on direct seeded or transplanted cabbage, cauliflower and broccoli grown on mineral soil in Canada. Prowl® Herbicide was already labeled for use on a number of crops in Canada for control of several weeds.
Continue reading Notice of minor use label expansion registration – Prowl H2O herbicide for cabbage, broccoli and cauliflower

67th Annual Muck Vegetable Growers Conference

The 67th Annual Muck Vegetable Growers Conference will be held March 28-29 at the Bradford and District Memorial Community located at 125 Simcoe St., Bradford, ON. The conference is free and registration starts at 8:30. No pre-registration is required. For more details please see:  http://www.uoguelph.ca/muckcrop/muckconference.html

Continue reading 67th Annual Muck Vegetable Growers Conference

Minor Use Label Expansion – Prowl H2O for transplant tomatoes on mineral soil

Jim Chaput – OMAFRA, Minor Use Coordinator

The Pest Management Regulatory Agency (PMRA) recently announced the approval of minor use label expansion registration for Prowl® H2O Herbicide for control of labeled weeds on transplanted field tomatoes grown in mineral soil in Canada. Prowl® H2O Herbicide was already labeled for use on a number of crops in Canada for control of several weeds.

This minor use project was submitted by Ontario as a result of minor use priorities established by growers and extension personnel.

The following is provided as an abbreviated, general outline only. Users should be making weed management decisions within a robust integrated weed management program and should consult the complete label before using Prowl® H2O Herbicide.

Crop Target Rate (L/ha) Application Information PHI (days)
Transplanted field tomatoes Labeled weeds 2.2 Apply once as a broadcast surface application prior to transplanting tomatoes 21

Prowl® H2O Herbicide is toxic to aquatic organisms and non-target terrestrial plants.  Do not apply this product or allow drift to other crops or non-target areas. Do not contaminate off-target areas or aquatic habitats when spraying or when cleaning and rinsing spray equipment or containers. In field tomatoes, do not apply Prowl® H2O Herbicide more than once in two consecutive years.

Follow all other precautions, restrictions and directions for use on the Prowl® H2O Herbicide label carefully.

For a copy of the new minor use label contact your local crop specialist, regional supply outlet or visit the PMRA label site https://www.canada.ca/en/health-canada/services/consumer-product-safety/pesticides-pest-management/registrants-applicants/tools/pesticide-label-search.html

Resources on weed management

Kristen Obeid, OMAFRA Weed Specialist – Horticulture

Internet

weedinfo.caWeedinfo.ca: If you are trying to identify a weed, find the newest information on herbicide resistance and other emerging issues in weed management you need to visit weedinfo.ca.

Provincial Weed Page: http://www.omafra.gov.on.ca/english/crops/insects/weeds.html

Ontario Crop IPM: Know how and why it is important to scout and identify weeds, as well as diagnose herbicide injury. Continue reading Resources on weed management

Tips for Broadleaf Weed Control in Pumpkins and Winter Squash

Originally published in ONvegetables in The Grower, April 2017

Even with the use of herbicides, broadleaf weed control in pumpkins and squash can be problematic. Product selection is key but timing and weather conditions are also important to the success or failure of a weed control program. Each of the broadleaf herbicides comes with its own strengths, weaknesses and risks.

As a general rule, the spectrum of weeds controlled can be increased by using tank-mixes. But, for pumpkins and squash, it is wise to limit the tank-mix to two products.  A three-way tank mix is risky from a crop safety standpoint; root damage, stunting, yellowing and/or burning may occur, especially under certain soil conditions.

All of the pre-emergence herbicides require soil moisture. The active ingredient is carried by the soil water into the germinating weed seedlings, causing them to die.  Under dry soil conditions, it is tempting to use overhead irrigation to “activate” the herbicides.  This is an inexact science.  Too much water can quickly move the herbicide band into the zone of the germinating crop roots, causing injury to the pumpkins or squash. Too little water may be insufficient to move the herbicide into the germinating weeds.

It becomes a gamble between loosing crop to herbicide damage or loosing yield to weed competition. Fortunately, both Dual II Magnum and Sandea can be used for early post emergence weed control.  Unfortunately, control of weeds such as lamb’s-quarters and pigweed is less effective with a post emergence spray.

Product: Command 360 ME (clomazone)
Timing:  after seeding but before crop and weed emergence.
Rate: 0.78-1.17 L/ha (0.31-0.47 L/acre) use the low rate on light, sandy loam soils; use the high rate on heavy soils.
Strengths: lamb’s-quarters, nightshades, ragweed, velvetleaf
Weaknesses: pigweeds.
Cautions: very sandy soils and/or certain varieties may be prone to crop injury, see label for details. Also refer to the label for rotational crop restrictions.

Product: Sandea (halosulfuron)
Timing(s): after planting and before soil cracking (direct seeded), before transplanting; do not transplant sooner than 7-days after application, OR post-emergence between the 3-5 true leaf stage or 14-days after transplanting[1]
Rate: 35-70 g/ha (14-28 g/acre). See the product label for specific rate information for direct seeded, transplanted, processing and fresh market pumpkins and squash.
Strengths: pigweeds, lady’s thumb, mustards
Weaknesses: lamb’s-quarters
Cautions: Under adverse growing conditions (dry or excessive moisture, cool weather, etc.) the maturity of the treated crop may be delayed which can influence harvest date, yield, and quality. Under dry soil conditions, apply 3 – 5 cm of sprinkler irrigation to settle the soil after planting and prior to application. Do not make a post emergence application if female blossoms are present on the plant; crop damage may occur to developing fruit.

[1] If using pre-emergence and post emergence applications of Sandea, allow for a minimum of 21 days between the two applications.

Product: Dual II Magnum (s-metolachlor/benxacor)
Timing:
pre-emergence or at the 1-2 leaf stage (direct seeded crops). Prior to transplanting or within 48 hours after transplanting (transplanted crops).
Rate: 1.15 L/ha (0.47 L/acre)
Strengths: annual grasses, nightshades, pigweeds
Weaknesses: lady’s-thumb, ragweed, velvetleaf
Cautions: risk of crop injury increases with cool and wet conditions. Foliar contact can increase the potential of crop injury. Note: research in Ontario has shown high levels of phytotoxicity when using Dual II Magnum on cucumber crops.  Use on cucumber crops is not recommended.

Prowl® H2O Herbicide label expanded for control of labeled weeds on direct seeded green onions grown on muck soil

Jim Chaput, Minor Use Coordinator

The Pest Management Regulatory Agency (PMRA) recently announced the approval of an URMULE registration for Prowl® H2O Herbicide for control of labeled weeds on direct seeded, green (bunching) onions grown on muck soil in eastern Canada and British Columbia. Prowl® H2O Herbicide was already labeled for use on a number of crops in Canada for control of weeds. Continue reading Prowl® H2O Herbicide label expanded for control of labeled weeds on direct seeded green onions grown on muck soil

Great new resource for this field season: Weed ID Guide for Ontario Crops

Kristen Obeid, Weed Management Specialist – Horticulture, OMAFRA

Published by the Grain Farmers of Ontario, the resource features over 120 species commonly found in and around agricultural fields. The Weed ID Guide for Ontario Crops is now available in the following formats:

These can be downloaded from the following website: http://fieldcropnews.com/2016/09/weed-id-guide-for-ontario-crops/

The publication was funded through Growing Forward 2, a federal-provincial-territorial initiative.