Crabgrass is probably one of the most hated weeds around Indiana.
It is a summer annual weed that germinates when soil temperatures are around 60-degrees. It is a grass weed that emerges from the ground with a single blade at first and has a fibrous root system.
Due to how annoying it can be to homeowners, it is important that you understand the various ways to control it from overtaking your lawn.
One of the best ways to control crabgrass is with a dense, healthy lawn. You can do this by maintaining a lawn that is about 3-inches high. When you mow too short, you actually promote the crabgrass population. Additionally, you should apply between two and four pounds of nitrogen per 1,000 square feet each year. You should apply the nitrogen in two applications in the fall.
To control crabgrass when your lawn is thin or new, you will have to combine cultural control with herbicide usage. Pre-emergence herbicides prevent the emergence of crabgrass and often needs to be applied before the middle of April. Most likely, you will only be able to find pre-emergence herbicides that have fertilizers mixed in. If you use a pre-emergence herbicide that is a "weed and feed" product, try to find one that has most of the nitrogen in a slow release format. If you have recently seeded your lawn, do not use a preemergence herbicide.
Post-emergence herbicides are used one the crabgrass has emergence from the soil. However, they are only effective if the plant is small. Post-emergence herbicides are more difficult to use and tend not to be as effective as preemergence herbicides on crabgrass. If you have not gotten your crabgrass under control by the middle of July, do not waste your time using an herbicide. At this time, it is too late to control the crabgrass and you should just let it grow. It will eventually die when the first frost hits.
If you do use an herbicide on your lawn, please take the time to look at the product label. The label will tell you how to mix the product. It is against the law to use any herbicide product in a manner that is not stated on the label.
No matter how hard you try to prevent and eliminate crabgrass, your fight might not be successful. Crabgrass has tremendous survival reproductive capabilities. Due to this, it is unrealistic to expect your lawn to be crabgrass free.
If you would like more information about crabgrass, look at Purdue Extension publication AY-10-W, "Control of Crabgrass in Home Lawns."
You can obtain your own copy by going to http://www.agry.purdue.edu/turf/pubs/AY-..., or by contacting your local Purdue Extension Office. This publication lists some of the active ingredients to look for when selecting an herbicide to use in your fight against crabgrass.
As always, if you have any questions or would like information on any agriculture, horticulture, or natural resource topic, then please contact your local Purdue Extension Office at 448-9041 in Clay County or 812-829-5020 in Owen County, or reach me directly at firstname.lastname@example.org.
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Upcoming opportunities available to you through Purdue Extension include:
* April 19 -- Area V P-CARET meeting,
* April 20 -- Clay County Share-The-Fun, and
* April 21 -- Community Farmers' Market of Owen County meeting, 6:30 p.m., Farm Bureau Office in Spencer.