There are two kinds of Crabgrass: ‘Big, Large, Hairy Crabgrass' (Digitaria sanguinalis) and ‘Small or Smooth Crabgrass' (Digitaria ischaemum).
Big or Large or Hairy Crabgrass
What does it look like?
The big brother of smooth crabgrass, this weed is just as unappealing, and perhaps a bit more difficult to deal with. It is a warm-season, annual grass weed, light green in color with a prostrate growth pattern.
When, where, and how does it grow?
Large crabgrass is found throughout the country, growing in the spring when soil temperatures reach 55°-58°F for 4-5 consecutive days. It is very hardy, returning each year from the prolific seedbed it leaves in the soil.
One single Big Crabgrass plant growing in your Lawn will produce 150,000 seeds before the end of the season. Many of them will be dormant and viable for several years. Another problem with Big Crabgrass; their roots produce a toxin that tends to kill off turf grass. As you can see the picture above, there is no other growth around the Big Crabgrass weed.
Small Crabgrass Seeds
Small Crabgrass
Both crabgrass varieties require full sun (they won't grow in the shade). Once the crabgrass weeds have been removed (I have found that cutting the leaves and stems and digging out the root to be the best avenue). Fill the hole with potting soil and let your grass grow and cut long. Mowing high is important because the length of the roots is determined by the height of the Grass. If you mow at 2 1/2 inches, the roots will grow 2 1/2 inches long. Let the grass provide the needed shade while eliminating room for weed roots. Higher grass with longer roots gives you weaker weeds.
There are many chemical/synthetic herbicides and pre-emergent weed treatments that control weeds, but at a cost to your grass. They kill off the natural soil bacteria and enzymes that keep your grass healthy. Chemical/synthetic fertilizers do the same. For a healthy, flush lawn go organic. Organic products are healthier for you, your kids, pets, and the environment.
Crabgrasses are the most common annual grass weeds in most lawns. Both the smooth and hairy types of crabgrass are classified as summer annual weeds. These grass weeds are considered undesirable in quality lawns because of incompatibility with desirable turf grasses.
Pre-emergent herbicides are chemicals that prevent the germinating weeds from establishing in the lawn. These herbicides control annual grass weeds by inhibiting cell division in the young root system. The failure of the root system to develop results in the death of the young seedling weeds shortly after germination.
Lawns with thin stands of grass that do not provide 100 percent cover may require yearly applications of a pre-emergent herbicide to prevent the invasion of crabgrass and other annual grass weeds. Dense, high-quality lawns may not need yearly applications since crabgrass only occasionally establishes in lawns with good density.
Pre-emergent herbicides are generally only effective if applied before the annual grass weeds emerge. Therefore, early spring applications are essential if satisfactory weed control is to be achieved. Herbicide applications should be completed and the herbicide watered-in at least 7 days prior to the initial germination date to allow time for the herbicide barrier to be established in the soil.
Pre-emergent herbicide applications for annual bluegrass control should be made in late summer or early fall.
If you have a pre-emergent herbicide applied to your lawn in the spring, you cannot reseed easily until the fall. Should the occasion arise where it is absolutely necessary to apply seed after a pre-emergent herbicide has been applied, rake the area thoroughly to help break the chemical shield in place. Apply some peat moss and rake in, then reseed.
I use Gluten-8 Organic Liquid Fertilizer is one of nature's best organic fertilizers and, it is also one of the best pre-emergent weed controllers. This product offers excellent weed control without the harmful effects of chemical/synthetic herbicides.
90 common lawn weeds with picture identification
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