Tag Archives: Weed Management

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.

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.

66th Annual Muck Vegetable Growers Conference

The 66th Annual Muck Vegetable Growers Conference will be held April 12-13 at the Bradford and District Memorial Community located at 125 Simcoe St., Bradford, ON. The conference is free and registration starts at 8:30. For more details please see:  http://www.uoguelph.ca/muckcrop/muckconference.html

Continue reading 66th Annual Muck Vegetable Growers Conference

Three Problem Weeds for Asparagus

The website, Ontario CropIPM, contains the full range of pest management information from many vegetable crops, including asparagus. Many users do not realize that it is also home to weed galleries, herbicide injury information and critical weed control period information. The following three problem weeds for asparagus are excerpts from the weeds and herbicides section of Ontario CropIPM. Continue scrolling for the best control options for each of the problem weeds. Continue reading Three Problem Weeds for Asparagus

Seasonal Topics – June 6, 2016

Tomato injury from PinnacleJune 6, 2016 — Some topics are relevant year after year, but you might not always take the time to filter through previous posts to find them. I’ve highlighted some here that might be of interest this week. Click on the preview images below to jump to the articles. Continue reading Seasonal Topics – June 6, 2016