Dallisgrass

Latin Name: Paspalum dilatatum

Identifying Characteristics:

  • Spreads by rhizomes, but grows in clumps
  • Greyish green color
  • Seed is located on the sides of numerous seedhead stalks
  • Similar appearance to crabgrass, but seedhead stalks and seed are larger

Plant Longevity:

  • Perennial warm-season grass

Where Commonly Found:

  • Pastures
  • Hay fields
  • Roadsides
  • Ditch banks

Time of Most Concern:

  • Late summer when seed heads are present
  • Humid conditions needed for development of ergot fungus

Compound that Causes Concern:

  • Ergot fungus, Claviceps paspali, produces the toxins paspalinine and two tremor-causing alkaloids paspalitrem A and B

Part of Plant Most Toxic:

  • Seed

Livestock Species Affected:

  • Cattle
  • Sheep
  • Horses
  • Goats

Pasture, Stored Feed, Both:

  • Both

Clinical Signs:

  • "Dallisgrass staggers"
    • Uncontrolled twitching
    • Sudden movements
    • Easily spooked
    • Swaying, incoordination, acting "drunk"
  • Diarrhea
  • Inability to stand
  • Distrust in people

Amount Needed to be Consumed for Clinical Signs / Death:

  • Rations containing more than 0.6% alkaloids are potentially toxic
  • Paspalinine toxicity is 8 mg compound / kg of body weight in mice
    • This translates to about 0.13 ounces for a 1000 lb cow
  • Paspalitrem toxicity is 14 mg compound / kg body weight in mice
    • This translates to about 0.22 ounces for a 1000 lb cow
  • No published studies in ruminants

Identifying Characteristics:

  • Spreads by rhizomes, but grows in clumps
  • Greyish green color
  • Seed is located on the sides of numerous seedhead stalks
  • Similar appearance to crabgrass, but seedhead stalks and seed are larger

Plant Longevity:

  • Perennial warm-season grass

Where Commonly Found:

  • Pastures
  • Hay fields
  • Roadsides
  • Ditch banks

Time of Most Concern:

  • Late summer when seed heads are present
  • Humid conditions needed for development of ergot fungus

Compound that Causes Concern:

  • Ergot fungus, Claviceps paspali, produces the toxins paspalinine and two tremor-causing alkaloids paspalitrem A and B

Part of Plant Most Toxic:

  • Seed

Livestock Species Affected:

  • Cattle
  • Sheep
  • Horses
  • Goats

Pasture, Stored Feed, Both:

  • Both

Clinical Signs:

  • "Dallisgrass staggers"
    • Uncontrolled twitching
    • Sudden movements
    • Easily spooked
    • Swaying, incoordination, acting "drunk"
  • Diarrhea
  • Inability to stand
  • Distrust in people

Amount Needed to be Consumed for Clinical Signs / Death:

  • Rations containing more than 0.6% alkaloids are potentially toxic
  • Paspalinine toxicity is 8 mg compound / kg of body weight in mice
    • This translates to about 0.13 ounces for a 1000 lb cow
  • Paspalitrem toxicity is 14 mg compound / kg body weight in mice
    • This translates to about 0.22 ounces for a 1000 lb cow
  • No published studies in ruminants

https://extension.msstate.edu/sites/default/files/newsletter/forage-news/2016/forage_newsletter_sept2016.pdf

Reddy et al. Tremorgenic Mycotoxins: Structure Diversity and Biological Activity. Toxins. 11(5), 302. 2019