Search
Better Farming OntarioBetter PorkBetter Farming Prairies

Better Farming Ontario Featured Articles

Better Farming Ontario magazine is published 11 times per year. After each edition is published, we share featured articles online.


Annual Weeds: A Game-Plan for 2024

Tuesday, February 27, 2024

Prepare to control these seven yield-limiting adversaries

Compiled by the Better Farming Editorial Team

Looking ahead to next growing season, you can be sure these uninvited guests will return, to compete with crops, steal essential nutrients, water and sunlight, and hinder profitability. This article looks at seven notorious annual weeds, diving into their characteristics, the threats they pose, and the best strategies to combat them for 2024.

#1. Lamb's quarters (Chenopodium album)

Lamb's Quarters
    Taste the Image - stock.adobe.com photo

Characteristics: Recognizable by its diamond-shaped leaves and powdery texture, this weed grows rapidly, sometimes towering up to five feet.

Impact: Historical data paints a concerning picture of its competitive nature with crops, especially corn and soybeans. If unchecked, Lamb's quarters can overshadow crops, stealing light and nutrients. Also, as Better Farming Crops columnist Patrick Lynch explains, "it was the first wide-spread weed that was resistant to triazines, including atrazine and metribuzin."

Control Measures: An integrated approach is indispensable. Herbicides like metolachlor and atrazine can be effective if your Lambs' quarters is not triazine resistant.

Unfortunately, in Ontario, most escapes are triazine-resistant. Additionally, crop rotation and ensuring herbicides penetrate the thick canopy of this weed can make a significant difference. This is especially the case if using glyphosate. "You must spray early at full rate," suggests Lynch.

#2. Pigweed (Amaranthus spp.)

Pigweed
    simona - stock.adobe.com photo

Characteristics: With a rapid growth rate and a tall, slender appearance, pigweed varieties, especially the Palmer amaranth, are resilient adversaries.

Impact: A single plant can produce up to half a million seeds, leading to quick infestation. Its aggressive nature can impact soybean yields significantly.

Control Measures: Diversifying herbicide usage helps counteract potential resistance. Pigweed was the first weed to exhibit resistance to Group 2 herbicides over a wide geography.

Additionally, practices like narrower row spacing hinder its rapid growth. Being proactive and targeting this weed during its early growth stages is crucial.

#3. Ragweed (Ambrosia spp.)

Ragweed
    Oskanov/iStock/Getty Images Plus photo

Characteristics: Beyond being the bane of allergy sufferers, ragweed plants can grow multiple branches with deeply lobed leaves.

Impact: Each ragweed plant is prolific, producing thousands of pollen grains and affecting both corn and soybean yields.

Control Measures: Herbicides with multiple modes of action can stall ragweed's advance. Regular scouting and timely intervention are also key. The advent of soybeans resistant to dicamba or 2,4-D should help to control this weed in 2024.

#4. Annual nightshade (Solanum spp.)

Annual Nightshade
    Mahato Photography - Wirestock Creators - stock.adobe.com photo

Characteristics: This weed boasts heart-shaped leaves and produces small berries that can contaminate grain shipments.

Impact: Direct competition and grain contamination are two-fold challenges posed by nightshade. Lynch warns that "if found in IP soybeans, the soybeans will probably be refused. This is because there once was a seed treatment that had the same colour as beans stained with nightshade berries. Buyers not wanting to take a chance just refused to accept beans stained with nightshade berries."

Control Measures: Lynch says that "in IP soybeans you need an herbicide pre-emerge that has good control of nightshade. Then you have to be prepared to come back with a post emergent herbicide. In corn there are lots of options."

#5. Volunteer corn (Zea mays)

Volunteer Corn
    Mahato Photography-Wirestock JJ Gouin - stock.adobe.com photo

Characteristics: While corn is a staple crop, plants that grow in subsequent seasons from unharvested seeds can become weeds themselves.

Impact: A weed is a plant growing out of place. Corn in a soybean field or volunteer corn in a corn field can be trouble.

To make things worse, volunteer corn in soybeans can host corn rootworm and making crop rotation to control rootworm ineffective.

Control Measures: Selective herbicides can target volunteer corn. Choose hybrids with good standability and harvest corn before ear drop. Lynch: "If you have a lot of fallen corn ears, mouldboard ploughing buries these ears to prevent them from germination next year."

#6. Fleabane (Conyza spp.)

Fleabane
    Oleh Marchak - stock.adobe.com photo

Characteristics: These are tall weeds with small flowers, often growing in clusters.

Impact: Glyphosate-resistant varieties are especially troublesome, impacting yields of both corn and soybeans.

Control Measures: Herbicides containing 2,4-D or dicamba are often recommended. There are numerous other herbicides to use. Lynch: "A quick check of OMAFRA's program to select herbicides by crop and by weed makes controlling this weed easy. Layering residual herbicides can prevent fleabane seeds from germinating."

#7. Chickweed (Stellaria media)

Chickweed
    avoferten - stock.adobe.com photo

Characteristics: A low-growing weed, chickweed has small, star-shaped flowers and thrives in cooler climates.

Impact: Primarily competing in the early growth stages, chickweed can be a direct threat to wheat. As well, it is a host for soybean cyst nematodes. A good stand of chickweed in the spring is an attractive place for armyworm or cutworm adults to lay their eggs.

Control Measures: Pre-emergent herbicides, especially when combined with early mowing, can effectively control chickweed. Crop rotation with non-host crops disrupts its lifecycle.

Integrated Weed Management (IWM)

A holistic approach: Combating these threats requires a more holistic strategy than merely reaching for the herbicide sprayer. IWM emphasizes combining chemical, cultural, and mechanical methods.

Farmer examining weed in soy field
    Emily Croft photo

Diversification: Both in terms of crops and herbicides. Diverse rotations can reduce weed seed banks, and using a variety of herbicides can prevent resistance.

Scouting: Regular field checks can identify weed threats early, allowing timely intervention.

Mechanical Controls: Tillage, mowing, and even hand-weeding can be effective, especially when integrated with other control measures.

Conclusion

With a nuanced understanding of these annual adversaries and a strategic approach to their management, Ontario producers can confidently look forward to the 2024 growing season. The foundation lies in knowledge, timely action, and integrated strategies. BF

(Editor's Note: Online sources were used in researching this article.)

Current Issue

October 2024

Better Farming Magazine

Farms.com Breaking News

5.5% values rise in Canadian farmland - FCC Report

Friday, October 11, 2024

FCC reports strong increase in Canadian farmland values According to Farm Credit Canada (FCC), Canadian cultivated farmland values experienced an average increase of 5.5% in the first half of 2024. Over the 12 months from July 2023 to June 2024, farmland values rose by 9.6%, although... Read this article online

OP-ED: Happy Agriculture Week from Minister Flack

Thursday, October 10, 2024

Rob Flack, Ontario's minister of farming, agriculture and agribusiness, provided the following message to celebrate Ontario Agriculture Week: Happy Ontario Agriculture Week! Every year during the week before Thanksgiving Monday, we celebrate the 871,000 people across the food supply... Read this article online

BF logo

It's farming. And it's better.

 

a Farms.com Company

Subscriptions

Subscriber inquiries, change of address, or USA and international orders, please email: subscriptions@betterfarming.com or call 888-248-4893 x 281.


Article Ideas & Media Releases

Have a story idea or media release? If you want coverage of an ag issue, trend, or company news, please email us.

Follow us on Social Media

 

Sign up to a Farms.com Newsletter

 

DisclaimerPrivacy Policy2024 ©AgMedia Inc. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Back To Top