ROOTED INRESEARCH
CRABGRASS—THE NUMBER ONE GRASSY WEED IN TURF
By Mike Fidanza, PhD
Mention the word “crabgrass” to most homeowners with a lawn, and you’ll get a negative response. Sod growers are not happy about that invasive grass, either. A recent survey of sod producers in Maryland indicated that their number one grassy weed is crabgrass.
But how did crabgrass find its way to the USA? European settlers into North America most likely transported crabgrass and crabgrass seeds in hay and straw. However, in 1849, the U.S. Patent Office introduced crabgrass as a potential forage crop. Crabgrass is an annual plant and a prolific seed producer. A mature crabgrass plant can produce over 100,000 seeds! So, perhaps all those seeds would make a nutritious forage crop for animal feed. Of course, that noble goal was not successful. Today you’ll find crabgrass in virtually every crop and non-crop site. Also today, the USDA’s APHIS (Animal and Plant Health Inspection Service) makes sure we don’t introduce invasive weed species into the country again.
Crabgrass was a concern over 100 years ago! Reprinted from the United States Golf AssociationGreen Section Record; August 22, 1921.
Today, many crabgrass species are distributed all over world, except Antarctica (and it’s probably there, too). So where did all this crabgrass come from? Botanical archaeology tells us that crabgrass most likely originated in either Africa or Asia. Large or hairy crabgrass (Digitaria sanguinalis) has African origins, and smooth crabgrass (Digitaria ischaemum) is from Europe or perhaps a Eurasian region. Large and smooth crabgrass are the most common in the USA, but other species found globally include Asian crabgrass, Carolina crabgrass, southern crabgrass, comb finger grass, woolly finger grass, longleaf crabgrass, Jamaican crabgrass, Madagascar crabgrass, shaggy crabgrass, Texas crabgrass, East Indian crabgrass, and more.
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Example of abundant seed production of a crabgrass plant. Photo courtesy of University of Arkansas (Fayetteville, AR).
What is the meaning behind those scientific names of Digitaria sanguinalis and Digitaria ischaemum? Digitaria is derived from digitus, the Latin word for "finger," which refers to the long, “finger-like” inflorescences these crabgrass plants produce. Tesanguinalis part of the name is derived
TPI Turf News July/August 2025
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