Field Guide     Weed Management     Large Crabgrass

Large Crabgrass (Digitaria sanguinalis)

Crop Impacts: Canola, Corn and Barley

Large Crabgrass 1

About Large Crabgrass:

Large Crabgrass is an annual weed that reproduces by seed. It is also very commonly known as Hairy Crabgrass. Large Crabgrass seed starts to germinate when the temperature 4 inches below ground stays between 11 ˚C and 14˚C at for 24 hours. Its germination period is dependent on the moisture and light in a specific location. It is a great indicator of elevated soil temperatures.

Family: Grass family (poacaea)

Large Crabgrass 2 Large Crabgrass 3

Large Crabgrass Scouting and Prevention:

Large Crabgrass as a seedling will form in clumps covered in coarse hair and is pale green in color. Their leaves start off curled up in a bud and as the plant matures, the leaves unroll. A mature plant can grow straight stems that range from 5 to 120 cm long. The stems can also lie along the ground. Large Crabgrass is heavily populated with leaves at the base of the plant and then begins to scatter along the rest of the stem. The leaves range from 4 to 20 cm long and gradually taper as it reaches the pointed tip. At the top of the stem there are thin, finger-like spikes that grow, which flower from July to September.

Common locations

  • - Canola fields
  • - Corn fields
  • - Barley fields
  • - Row crops
  • - Gardens
  • - Lawns
  • - Pastures

Prevention

Applying pre-emergent herbicides during the spring when soil temperatures are about 10˚C can provide good control. However, a second application about 8 weeks after the first treatment is most likely necessary for season-long control over Large Crabgrass. After good pre-emergent herbicide application, followed by clean cultivation, gives desired plants a chance to compete against Large Crabgrass. Planting small grains and crops that have an early establishment provide a great environment to repress the growth of Large Crabgrass due to the fact that it won’t be able to compete.

Large Crabgrass Control:

Large Crabgrass is not a weed that can be controlled in one growing seasons due to the fact that there are numerous viable seeds that accumulate in the ground from many years of infestation. The best way to deal with Large Crabgrass is controlling the production of seeds for many years. This will eventually diminish the viable seed supply in the soil so that it is no longer a major threat to your crops, gardens and lawns.

Cultural Control

Small patches of Large Crabgrass can be removed by hand. As for gardens and row crops, tillage can be just as effective and more efficient. It must be regularly repeated to prevent regrowth.

Chemical Control

It is important to note that all Large Crabgrass is resistant to all WSSA group 1 herbicides. However, herbicides with active ingredients prometon or trifloxysulfuron-sodium have very high efficiency rates in eradicating Large Crabgrass.

Latin / Alternative Large Crabgrass names:

  • - Digitaria sanguinalis
  • - Hairy crabgrass

Additional Large Crabgrass Resources

http://www.cropscience.bayer.ca/Pest-Finder/Weeds.aspx#Keywords%2Flarge%20crabgrass%3B%7C

http://www.omafra.gov.on.ca/english/crops/facts/ontweeds/large_crabgrass.htm

https://www.gri.msstate.edu/ipams/species.php?SName=Digitaria%20sanquinalis

http://www.turffiles.ncsu.edu/weeds/Crabgrass_Large.aspx

http://extension.psu.edu/pests/weeds/weed-id/large-crabgrass