Johnson grass (Common name)

General poisoning notes:

Johnson grass (Sorghum halepense) is a naturalized herb found as a weed in only a few counties of southwestern Ontario. This plant can produce toxic quantities of HCN if it is damaged through frost, mastication, or water stress. Johnson grass can also accumulate toxic amounts of nitrate under certain circumstances. Cattle and a horse were poisoned after ingesting Johnson grass. Plants are spread from rhizomes but susceptibility to severe frost has limited the plants to a few counties in southwestern Ontario. The grass is found in fields and field edges. Toxicity is not likely, but ingesting large quantities of Johnson grass can cause problems (Gray et al. 1968, Clay et al. 1976, Warwick and Black 1983).

References:

  • Clay, B. R., Edwards, W. C., Peterson, D. R. 1976. Toxic nitrate accumulation in the sorghums. Bovine Pract., 11: 28-32.
  • Gray, E., Rice, J. S., Wattenbarger, D., Benson, J. A., Hester, A. J., Loyd, R. C., Greene, B. M. 1968. Hydrocyanic acid potential of Sorghum plants grown in Tennessee. Tenn. Agric. Exp. Stn. Bull., 445. 48 pp.
  • Reynard, G. B., Norton, J. B. 1942. Poisonous plants of Maryland in relation to livestock. Univ. MD. Agric. Exp. Stn. Bull., A10. 312 pp.
  • Warwick, S. I., Black, L. D. 1983. The biology of Canadian weeds. 61. Sorghum halepense (L.) Pers. Can. J. Plant Sci., 63: 997-1014.

Nomenclature:

Scientific Name:
Sorghum halepense (L.) Pers.
Vernacular name(s):
Johnson grass
Scientific family name:
Gramineae
Vernacular family name:
grass

Go to ITIS*ca for more taxonomic information on: Sorghum halepense

References:

  • Agriculture Quebec. 1975. Noms des maladies des plantes du Canada/ Names of plant diseases in Canada. , Quebec City, Que., Canada. 288 pp.
  • Alex, J. F., Cayouette, R., Mulligan, G. A. 1980. Common and botanical names of weeds in Canada/Noms populaire et scientifiques des plantes nuisibles du Canada. Revised. Agric. Can. Publ., Ottawa, Ont., Canada. 132 pp.
  • Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.
  • Scoggan, H. J. 1978, 1979. The flora of Canada. Nat. Mus. Nat. Sci. (Ottawa) Publ. Bot. 7(1)-7(4). 1711 pp.
  • Van Wijk, H. L. 1911. A dictionary of plant names. Martinus Nijhoff, The Hague, The Netherlands. 1444 pp.
  • Victorin, M. 1964. Flore Laurentienne. 2nd ed. Univ. Montreal, Montreal, Que., Canada. 952 pp.

Geographic Information

  • Ontario

References:

  • Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.
  • Boivin, B. 1966, 1967. Énumération des plantes du Canada. Provencheria 6. Nat. Can. (Que.) 93: 253-274; 371-437; 583-646; 989-1063. 94: 131-157; 471-528; 625-655.

Image or illustration

Images: Johnson grass - Google Search

Notes on Poisonous plant parts:

The hydrocyanic potential of Johnson grass is largest during early growth of the plant (Gray et al. 1968).

Toxic parts:

  • leaves
  • stems

References:

  • Gray, E., Rice, J. S., Wattenbarger, D., Benson, J. A., Hester, A. J., Loyd, R. C., Greene, B. M. 1968. Hydrocyanic acid potential of Sorghum plants grown in Tennessee. Tenn. Agric. Exp. Stn. Bull., 445. 48 pp.
  • Sharma, R. P., Salunkhe, D. K. 1989. Solanum glycoalkaloids. Pages 179-236 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

Notes on Toxic plant chemicals:

A cyanogenic glycoside, dhurrin, is found in Johnson grass. After the plant has been damaged by mastication, plant enzymes convert the glycoside to other chemicals, including HCN. Cyanide, which is lethal, is released into the animal''s system . Nitrates can accumulate under some circumstances. Nitrate poisoning has occurred in cattle (Gray et al. 1968, Clay et al. 1976).

Toxic plant chemicals:

  • chaconine
  • dhurrin
  • nitrate

Chemical diagram(s) are courtesy of Ruth McDiarmid, Biochemistry Technician, Kamloops Range Station, Agriculture and Agri-Food Canada, Kamploops, British Columbia, Canada.

References:

  • Clay, B. R., Edwards, W. C., Peterson, D. R. 1976. Toxic nitrate accumulation in the sorghums. Bovine Pract., 11: 28-32.
  • Gray, E., Rice, J. S., Wattenbarger, D., Benson, J. A., Hester, A. J., Loyd, R. C., Greene, B. M. 1968. Hydrocyanic acid potential of Sorghum plants grown in Tennessee. Tenn. Agric. Exp. Stn. Bull., 445. 48 pp.
  • Sharma, R. P., Salunkhe, D. K. 1989. Solanum glycoalkaloids. Pages 179-236 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Cattle

General symptoms of poisoning:

Notes on poisoning:

Johnson grass can accumulate toxic levels of nitrates, which leads to methemoglobinemia. In severe cases, death can occur 4-6 h after ingestion. Three to five days after acute poisoning, surviving pregnant animals may abort (Clay et al. 1976). Dhurrin, a cyanogenic glycoside, is found in plant material. When the plant is damaged by frost, mastication, or water stress, HCN can be released and cyanide can enter the animal's system. Symptoms are the result of cytotoxic hypoxia, leading in severe cases to death from asphyxiation. Other symptoms include increased respiration, irregular pulse, frothing at the mouth, and staggering (Gray et al. 1968, Fuller and McClintock 1986).

References:

  • Clay, B. R., Edwards, W. C., Peterson, D. R. 1976. Toxic nitrate accumulation in the sorghums. Bovine Pract., 11: 28-32.
  • Gray, E., Rice, J. S., Wattenbarger, D., Benson, J. A., Hester, A. J., Loyd, R. C., Greene, B. M. 1968. Hydrocyanic acid potential of Sorghum plants grown in Tennessee. Tenn. Agric. Exp. Stn. Bull., 445. 48 pp.

Horses

General symptoms of poisoning:

Notes on poisoning:

In Maryland a horse died from cyanide poisoning after ingesting Johnson grass (Reynard and Norton 1942).

References:

  • Reynard, G. B., Norton, J. B. 1942. Poisonous plants of Maryland in relation to livestock. Univ. MD. Agric. Exp. Stn. Bull., A10. 312 pp.

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