Skip to main content

NC State Extension

Lecture 2: Principles & Tools

en Español / em Português

El inglés es el idioma de control de esta página. En la medida en que haya algún conflicto entre la traducción al inglés y la traducción, el inglés prevalece.

Al hacer clic en el enlace de traducción se activa un servicio de traducción gratuito para convertir la página al español. Al igual que con cualquier traducción por Internet, la conversión no es sensible al contexto y puede que no traduzca el texto en su significado original. NC State Extension no garantiza la exactitud del texto traducido. Por favor, tenga en cuenta que algunas aplicaciones y/o servicios pueden no funcionar como se espera cuando se traducen.


Inglês é o idioma de controle desta página. Na medida que haja algum conflito entre o texto original em Inglês e a tradução, o Inglês prevalece.

Ao clicar no link de tradução, um serviço gratuito de tradução será ativado para converter a página para o Português. Como em qualquer tradução pela internet, a conversão não é sensivel ao contexto e pode não ocorrer a tradução para o significado orginal. O serviço de Extensão da Carolina do Norte (NC State Extension) não garante a exatidão do texto traduzido. Por favor, observe que algumas funções ou serviços podem não funcionar como esperado após a tradução.


English is the controlling language of this page. To the extent there is any conflict between the English text and the translation, English controls.

Clicking on the translation link activates a free translation service to convert the page to Spanish. As with any Internet translation, the conversion is not context-sensitive and may not translate the text to its original meaning. NC State Extension does not guarantee the accuracy of the translated text. Please note that some applications and/or services may not function as expected when translated.

Collapse ▲

• Site Preparation
• Sanitation & Exclusion
• Mulches
• Preemergence Herbicides
• Postemergence Herbicides
• Hand weeding

Site Preparation

The best time to control perennial weeds is before planting.

There are basically three options: repeated cultivation, fumigation, or glyphosate (Roundup).

If the site is to be amended with topsoil or organic matter, inspect the sources of these materials for noxious weeds. Topsoil from farmland or stream banks is notorious as a source of nutsedge tubers and seeds of many annual weeds like morningglory and sicklepod. Inspect piles of compost or mulch for signs of weeds. Some species frequently found in mulch piles include mugwort, thistle, spurge, bindweed, and field horsetail. If these weeds are present, find an alternate source!


Repeated cultivation on a regular schedule will control most weeds. Area will have to be left fallow for at least one full year possibly two. Generally not an option in landscape plantings.

Glyphosate (Roundup-Pro & others)

Nonselective, systemic herbicide that kills most weeds – shoots and roots. Note that even Roundup does not control all weeds. For species like nutsedge, Florida betony, field horsetail (Equisetum), and wild violet, fumigation may be necessary.

Site Preparation with Glyphosate (Roundup-Pro & Others)

• Timing is critical for perennial weed control. Some species are well controlled in the fall but not in the spring; and vice versa. (We will cover this in more detail later.)
• Understand what can be controlled and what cannot.

Fumigation is the option of last resort

Fumigants are very toxic, expensive and require significant site preparation.
If this is to be done — DO IT RIGHT!


Using the sun’s energy to build heat in the soil; thereby killing weed seeds and vegetative propagules. Not as effective as Fumigation but simpler. Requires significant time and only effective in the summer. Even then, many perennial weeds will not be controlled. Not widely used.

Effectiveness of Pre-plant Weed Control Measures on Certain Hard-to-Kill Perennial Weeds

Species Roundup
Roundup Spring Fumigation Cultivation
Bindweed Good Poor Fair Poor
Japanese knotweed Good Poor Good Good
Mugwort Good Poor Fair Poor
Canada thistle Good Fair Good Fair
Wild Violet Poor Poor Good Good
Goldenrod Good Poor Good Good
Nutsedge Poor Poor Good Poor
Bamboo Poor Poor Good Good
Johsongrass Good Fair Good Poor
Bermudagrass Fair Fair Good Poor
Equisetum Poor Poor Fair Poor

Study Questions:

  1. What are the 3 main options for weed control at site preparation?
  2.  How do you know if fumigation is necessary?
  3.  If you have a landscape bed infested with crabgrass, henbit and other common annual weeds would you advise fumigation?
  4. Goldenrod is well controlled by cultivation. Why is this not a feasible option in landscape bed installation?
  5. Roundup (glyphosate) is non-selective. Under what situations would it not provide acceptable control for site preparation?