Weed Control
Definition of a weed
A weed is any plant growing where it is not wanted. Lawn weeds belong to one of three categories: broadleaf, grassy, or grass-like. A typical broadleaf weed is a dandelion. Crabgrass is in the grassy weed category, while nutsedge would be classified as a grass-like weed.

Types of Herbicides:

Pre-emergent Weed Killer
One of the most effective ways to control weeds is to apply pre-emergent herbicide, a chemical that prevents unwanted growth from appearing.
Contrary to popular belief, pre-emergent weed killers don't destroy weeds and their seeds. They simply stop them from growing. There is no silver bullet that kills all weeds and an effective program adjusts to the needs of the property on a seasonal or annual basis. While fighting weeds is a year-round job, weed prevention is best practiced in the fall and early spring to take advantage of the growing season of turf grasses. A healthy, thick lawn is your number one defense against weeds.
Post-Emergent Weed Killer
Post emergent herbicides are weed killers that are applied to weeds that are actively growing above ground. A topical spray that when sprayed on many lawn weeds will yellow out and kill the weed to the root. Some types of weeds like clover require 2 applications of post emergent. As the name of the product implies, it is formulated to kill the weeds AFTER they have germinated as opposed to before they have germinated (pre emergent).


Here is a centipede lawn that has been treated with post emergent, spray on application, 10 days after the chemical was applied. Note that the weeds are yellowing out while the grass remains unaffected.

Crabgrass

Nutsedge

Dandelion
Owner, Terry Loper has a Commercial Category 24 Ornamental and Turf Applicator license.