Crabgrass

Crabgrass is an annual and perennial lawn, pasture and forage plant. They are largely considered lawn pests. It is difficult to get rid of and is capable of producing 150,000 seeds per season. Despite being classified as a weed by many, crabgrass has several uses. It's seeds can be ground into flour which can be used to make porridge or beer. Crabgrass seeds have also been widely used as food in Africa.

Anatomy
There are two types of crabgrass, D. ischaemum and D. sanguinalis (or large crabgrass and smooth crabgrass). Large crabgrass is usually flat, has purple stems and can grow about 3 feet in height. Smooth crabgrass can only grow about 15 inches. The leaves of the large crabgrass are turquoise, have pubescent on both sides and have a rough margin. They are flat, sharply pointed and they can grow from 1/4 - 2/5 inches wide, and 2-6 inches long. Smooth crabgrass leaves are a dull green and can have a hint of purple in them. Just like the large crabgrass leaves, the leaves on the smooth crabgrass are also pointed, have a rough margin and pubescent near the base of the leaf, but the smooth crabgrass leaves only grow 1/8 - 1/4 inches wide and 1-4 inches long.

Reproduction
Large crabgrass is arguably one of the most troublesome weed there is to have in your lawn. All crabgrass reproduce by seeds and has prolific tillering (a plant shoot that comes up from the roots or the original stalk) or branching habits. Each plant is able to have about 150 to 700 tillers and over 150,000 seeds. Crabgrass can be very adaptive to the mowing it can still produce seeds at 1/2 inches. When crabgrass is ready to germinate the temperature in the soil plays a big part in that. If the temperature of the soil is around 60 degrees F. crabgrass will germinate, but to be able to germinate, the temperature has to be the same for about a week. The best time for the seeds to germinate is from early spring to late summer. The seeds of the crabgrass plant will be dormant for a while once they leave the plant. In the midsummer, crabgrass will still be growing even when the days are getting shorter. When the vegetative growth starts to slow down, the reproductive cycle will begin. The purple seeds will start to grow until the snow comes and kills the plant. The plants that start to come up earlier will have a better chance in germinating than the ones that start later in the season.

Ecology
Crabgrass is one of the toughest weeds to get rid of in the United States. There have been many tests done on crabgrass to see the distribution and adaption of different regions and cropping systems. The results show that the three major species of crabgrass are the smooth, large and southern. Large crabgrass is the most prominent of the three during the cropping systems, from orchards to forage crops to golf and other turf areas. Smooth crabgrass becomes more of a problem in turf from the other systems. The limit of the distribution of crabgrass and the adaption of crabgrass varies depending on the temperature, light, and seed bank.

Prevention
There are many ways to get rid of crabgrass but you must be careful not to destroy your lawn in the process. The first way to prevent crabgrass is to read the labels on the herbicides that you buy. Using pre-emergent herbicides will help with killing off crabgrass before it has the chance to germinate and spread seeds, and using it in late winter/early spring when the weather is about 55 degrees will help with the prevention of blooming. Cutting the crabgrass short will cut down on the seeds for next season, but the most efficient way to remove crabgrass without herbicides is to pull on the leaves and make sure to get the roots.