Weeds – how to identify, prevent and get rid of

Weeds – how to identify, prevent and get rid of

Winning the War Against Weeds

“Weeds – they’re all I can grow!” This was what I always heard growing up and consequently why we never had a garden. If Weeds could write a book, it would be titled “How to triumph over all else and take over the world”. Left to run amuck, weeds can quickly make themselves at home in your yard, fields and pastures making themselves comfy and not leaving room for much else.

For agriculture – weeds take on a whole new role. Weeds can greatly impact crop success and therefor harvest, the bottom line and feed quality. Weeds have one goal in mind, and that’s to be aggressive and survive. For farmers, this poses a threat to crop nutrients and weeds have to be addresses quickly.

In this post we will look at some common weeds that effects growers, how to identify them, how you can prevent them from growing and how to get rid of these prickly foes.


Palmer Amaranth


What is Palmer Amaranth?

Palmer Amaranth is a species of edible flowering plant in the amaranth genus. Originating from the arid southwestern United States and northwestern Mexico, it’s found its way into fields across the country, earning the notorious reputation as one of the most troublesome weeds in the agricultural world.

This persistent annual weed is capable of rapid growth and producing an enormous amount of seeds, making it a significant threat to crops. It’s aggressive, resilient, and capable of developing resistance to herbicides, making it a formidable foe for growers everywhere.

Identifying Palmer Amaranth

Recognizing Palmer Amaranth early is crucial in preventing its establishment and spread. Here’s how you can identify it:

  1. Leaves: Palmer Amaranth has long, ovate to diamond-shaped leaves that are arranged alternately along the stem. The leaf surface is hairless, and the leaf petiole (stalk) is often as long as, or longer than, the leaf blade itself.
  2. Stem: The stem of this weed is smooth and vertically erect, growing up to 2 meters tall.
  3. Flowers and Seeds: Palmer Amaranth bears small greenish flowers on long, terminal inflorescences, which can be up to 1 meter long in mature plants. Male and female flowers are borne on separate plants. The female plants produce copious amounts of small, shiny, black seeds.
  4. Spatulate Leaf: Palmer Amaranth seedlings often have a spatulate (spoon-shaped) leaf visible below the first pair of true leaves. This can be a good indicator at the seedling stage.
  5. Long Petioles: The length of the petiole compared to the leaf blade can help distinguish Palmer Amaranth from other similar-looking weeds.

Preventing Palmer Amaranth

Prevention is always better than cure. Here are some strategies to prevent Palmer Amaranth:

  1. Clean Equipment: Palmer Amaranth seeds can be transported from one field to another by contaminated equipment. Always ensure equipment is thoroughly cleaned before moving it from a contaminated field.
  2. Scout Fields: Regular field scouting is essential, especially during the early part of the growing season, to identify and manage Palmer Amaranth before it gets established.
  3. Crop Rotation and Cover Crops: Utilize crop rotation and cover crops. These practices increase the diversity of plant species in your fields, which can suppress weed growth.
  4. Limit Soil Disturbance: Limiting soil disturbance can help reduce weed seed germination. Tillage brings weed seeds to the soil surface where they can germinate.

Getting Rid of Palmer Amaranth

Even with prevention, Palmer Amaranth can still find its way into your fields. Here are steps to manage and control this resilient weed:

  1. Early Detection and Removal: Scout your fields early and often. Hand-pulling young Palmer Amaranth plants before they produce seeds can prevent further infestation. Remember, one mature Palmer Amaranth plant can produce hundreds of thousands of seeds.
  2. Herbicide Application: Use pre-emergent herbicides to control Palmer Amaranth seeds before they germinate. Additionally, post-emergent herbicides can be used on young Palmer Amaranth plants. However, be aware of the risk of herbicide resistance. Rotate modes of action and use herbicides as part of an integrated weed management system. 


Image taken from the Tualatin Conservation District

This weed is notorious for its beautiful but problematic spiraling vines. Bindweed is a robust perennial that poses a significant threat to agricultural productivity.

What is Bindweed?

Bindweed, encompassing species such as Field Bindweed (Convolvulus arvensis) and Hedge Bindweed (Calystegia sepium), is a perennial vine with a deep and extensive root system. It’s native to Europe and Asia but has spread its tendrils across the globe, causing significant crop losses in its wake.

Bindweed is hardy and highly adaptable, being capable of thriving in a wide range of soil types and conditions. It’s recognized for its trumpet-shaped flowers, which may look attractive but can strangle crops and outcompete them for essential resources like nutrients, light, and water.

Identifying Bindweed

Here’s how you can spot this troublesome weed in your fields:

  1. Leaves: Bindweed leaves are arrowhead-shaped and alternate along the stem. They are typically green, although their shade can vary depending on environmental conditions.
  2. Stem: The stems of bindweed are long, slender, and possess a vine-like quality, allowing them to twine around other plants and structures.
  3. Flowers and Seeds: Bindweed flowers are trumpet-shaped, usually white or pink, and bloom from late spring to early fall. They produce small, brown, four-sided seeds that can remain viable in the soil for many years.
  4. Roots: Field Bindweed, in particular, has a deep, extensive root system that can penetrate the soil up to 5 meters deep. This makes the weed incredibly resilient and hard to eradicate completely.

Preventing Bindweed

Prevention remains the best way to manage bindweed. Here are some strategies:

  1. Regular Monitoring: Regularly inspect your fields to identify any early signs of bindweed infestation. Early detection is key to managing this weed.
  2. Clean Equipment: As with any weed, bindweed seeds and plant fragments can hitch a ride on farming equipment, spreading the infestation to new areas. Always clean your equipment thoroughly.
  3. Good Hygiene Practices: Use clean, certified seed and feed to prevent introducing bindweed into your fields.
  4. Healthy Crops: Maintain the health and vigor of your crops to better compete against bindweed.

Getting Rid of Bindweed

Should bindweed establish itself in your fields, here’s what you can do to control it:

  1. Mechanical Control: Regular mowing or cutting can weaken bindweed over time. However, it’s not a quick fix due to the weed’s extensive root system.
  2. Chemical Control: Herbicides can be effective in controlling bindweed, but it usually requires repeated applications over several seasons due to the weed’s deep root system. Always follow label instructions when using herbicides.
  3. Biological Control: Some insects and fungi have been found to attack bindweed, although these are not yet widely available for use.
  4. Integrated Management: Due to the resilient nature of bindweed, using a combination of cultural, mechanical, and chemical methods over several years often provides the most effective control.

Bindweed is a formidable opponent in the battle for crop productivity, but with careful planning, early detection, and persistent management, it can be controlled and suppressed. Remember, there’s no ‘one-size-fits-all’ solution in weed management – it takes consistent effort and a well-rounded strategy to keep your fields clear.


Image taken from Aglifetoday.com

Another common yet formidable weed found in many farming landscapes – Kochia (Bassia scoparia), also known as Mexican Fireweed, Summer Cypress, or Fireweed.

What is Kochia?

Kochia, a native of Eurasia, is a problematic annual weed that has made itself quite at home in North America. It has an extraordinary ability to adapt to various environmental conditions, showing particular resilience in drought-like situations and high-salinity soils, making it a challenge in many arid and semi-arid regions.

The plant, if left unchecked, can produce thousands of seeds and has a propensity for developing resistance to several classes of herbicides. Its ability to compete with crops for essential resources can lead to significant yield loss.

Identifying Kochia

Here’s how to spot this unyielding adversary in your fields:

  1. Leaves: Kochia leaves are narrow, lance-shaped, and alternate along the stem. They are usually green but can change to a reddish color as the plant matures.
  2. Stem: Kochia typically grows between 1-7 feet tall, bearing a central stem from which numerous branches sprout, giving it a broom-like or Christmas tree-like appearance. The stems are green to red, smooth, and often show a striped pattern.
  3. Flowers and Seeds: Kochia’s green flowers are small and hardly noticeable, found in clusters in the upper leaf axils. The plant produces small, flattened, and black seeds.
  4. Overall Appearance: At maturity, Kochia’s bushy growth habit, along with its unique reddish color in late summer to fall, makes it quite distinguishable in the field.

Preventing Kochia

Prevention is a crucial aspect of weed management. Here are some steps you can take:

  1. Regular Monitoring: Frequently scout your fields, especially during the early growing season, to catch any early signs of Kochia.
  2. Clean Equipment: Ensure all farm equipment is thoroughly cleaned between fields to prevent unintentional seed spread.
  3. Crop Rotation and Cover Crops: These practices not only contribute to soil health but also can prevent the establishment and proliferation of Kochia.

Getting Rid of Kochia

If Kochia has already established in your fields, here’s how to control it:

  1. Mechanical Control: Small Kochia populations can be controlled via pulling or mowing before the plant sets seed. Remember, a single Kochia plant can produce thousands of seeds, so timely removal is key.
  2. Chemical Control: Using pre-emergence and post-emergence herbicides known to be effective against Kochia can offer some control. But, be mindful of potential herbicide resistance and always rotate modes of action.
  3. Cultural Control: Planting competitive crops, using cover crops, and maintaining good soil fertility can help suppress Kochia.

Kochia is a challenging weed, but with an integrated weed management plan that combines cultural, mechanical, and chemical strategies, it can be effectively controlled. Remember, the most effective weed control is a proactive approach that starts with good farm sanitation, regular field monitoring, and timely intervention.


Image taken from UNCR

A perennial foe in the world of agriculture: Johnsongrass (Sorghum halepense). Notorious for its rapid growth and extensive root system, Johnsongrass ranks among the top ten most troublesome weeds worldwide.

What is Johnsongrass?

Johnsongrass, native to the Mediterranean region, is a tall, coarse, perennial grass that’s become naturalized across much of the United States. It can thrive in a variety of environmental conditions, making it a significant concern for farmers, gardeners, and those who manage lawns and turf.

Johnsongrass is highly competitive and can reduce crop yields by competing for resources such as light, water, and nutrients. It can quickly spread through both its prolific seed production and its extensive, creeping, underground stems known as rhizomes.

Identifying Johnsongrass

Here’s how to recognize this invasive weed:

  1. Leaves: Johnsongrass leaves are large and lance-shaped, reaching up to a foot long and an inch wide. They have a prominent white midrib and a smooth, glossy surface.
  2. Stem: Johnsongrass stems can grow up to six feet tall. They are erect and often have a reddish tint at the base.
  3. Flowers and Seeds: The grass produces large, purplish, branched clusters of flowers, called panicles, which can reach up to 20 inches long. The seeds are small, round, and dark brown to black.
  4. Roots and Rhizomes: Johnsongrass has a robust root system featuring aggressive rhizomes that can grow up to several feet long, allowing the plant to spread rapidly and recover from control attempts.

Preventing Johnsongrass

To prevent Johnsongrass from establishing in your fields, consider these strategies:

  1. Regular Monitoring: Regularly scout your fields, especially during the early growing season, to catch any early signs of Johnsongrass.
  2. Clean Equipment: Clean all farm equipment thoroughly between fields to prevent the spread of rhizome fragments and seeds.
  3. Crop Rotation: Use crop rotation with competitive crops that can suppress Johnsongrass growth.

Getting Rid of Johnsongrass

If Johnsongrass has already established in your fields, here’s how to control it:

  1. Mechanical Control: Regular mowing can reduce Johnsongrass’ vigor by depleting energy reserves in its rhizomes, but it must be done before seed set. Tillage can be used to break up rhizomes, but care should be taken as fragments can lead to new plants.
  2. Chemical Control: Herbicides can provide control of Johnsongrass, especially when plants are young. However, repeated applications are often required due to the weed’s extensive root system.
  3. Cultural Control: Planting competitive crops and maintaining good soil fertility can help suppress Johnsongrass. In non-crop areas, establishing dense, competitive turfgrass can help keep Johnsongrass in check.

Johnsongrass is a challenging weed, but with a committed, integrated weed management plan and persistent efforts, it can be controlled. Remember, effective control starts with prevention, timely detection, and consistent action. The battle against Johnsongrass is a marathon, not a sprint, but with determination and the right strategies, victory is achievable.


Image taken from USU edu site

Puncturevine is a prickly opponent that goes by many names – Puncturevine, Goat’s Head, Caltrop, or scientifically, Tribulus terrestris.

What is Puncturevine?

Originally from the Mediterranean region, Puncturevine is a low-growing, annual broadleaf plant that has successfully colonized many parts of the world, including North America. This invasive weed is particularly suited to dry climates and thrives in disturbed soils, such as those found in overgrazed pastures, fields, orchards, vineyards, roadsides, and gardens.

The plant gets its name from its distinctive, hard, spiny fruits which can easily puncture bicycle tires, footwear, and unfortunately, the skin of humans and animals alike. The seeds within these fruits contribute to the weed’s tenacious nature and its propensity to infest new areas.

Identifying Puncturevine

Here are key characteristics to help identify this prickly pest:

  1. Leaves: Puncturevine has compound leaves with four to eight pairs of leaflets. The leaflets are hairy and opposite each other along the stem.
  2. Stem: The stems are hairy, light green to reddish, and branch out, radiating from the crown and forming a mat-like appearance.
  3. Flowers and Seeds: Puncturevine flowers are small, yellow, and have five petals. The notorious fruits are hard, woody, and spiky, typically containing four to five seeds.
  4. Roots: Puncturevine has a deep taproot, which allows it to survive in harsh conditions and recover from control attempts.

Preventing Puncturevine

To prevent a Puncturevine infestation, consider these strategies:

  1. Regular Monitoring: Regularly check your fields, paying close attention to areas with disturbed soils and field edges.
  2. Clean Equipment: Make sure all farming equipment is thoroughly cleaned after use to prevent the spread of Puncturevine seeds.
  3. Healthy Soil and Crops: Maintaining healthy soils and vigorous crops can help outcompete Puncturevine.

Getting Rid of Puncturevine

If Puncturevine has made its home in your fields, here’s how to fight back:

  1. Mechanical Control: Manual removal, including hand-pulling or hoeing, can be effective for smaller infestations. Be sure to dispose of the plants properly to avoid spreading the seeds.
  2. Chemical Control: Herbicides can provide effective control of Puncturevine, especially when applied while the plants are young and actively growing.
  3. Biological Control: Certain weevils are known to feed on Puncturevine seeds and can help in managing this weed, especially in larger infestations.
  4. Cultural Control: Planting competitive crops and groundcovers can help suppress Puncturevine. Also, maintain proper irrigation and fertilization to support the growth of desirable plants.

While Puncturevine is a formidable adversary, its proliferation can be controlled. Success lies in early detection, constant vigilance, and an integrated weed management approach. With these strategies in your farming toolkit, you can safeguard your fields from this prickly invader.

Next Steps

Weed management, like farming itself, requires dedication and patience. It’s about more than just recognizing a weed and pulling it out or spraying it down. It’s about understanding each weed’s life cycle, knowing when it’s most vulnerable, and tailoring your actions to target these weaknesses.

Most importantly, successful weed management revolves around integrating various control methods – cultural, mechanical, and chemical – and modifying these strategies as conditions change. Regular field monitoring, using clean equipment, selecting competitive crops, and judicious use of herbicides, these all form the arsenal you have at your disposal to protect your yield and productivity.

Remember, every weed you control today is an investment in the health and prosperity of your fields tomorrow. Armed with knowledge and the right tools, you can stand your ground against these invasive species and protect your farm’s productivity and profitability.

Here’s to bountiful yields and weed-free fields! Until next time, happy farming!