Noxious Weeds Profile
- Johnson Grass
Table of Contents
- Current Status
- Growth Habit
- Method of Propagation
- Other Comments
- Related Links
- English - Johnson grass
- French - sorgho d'Alep
- Latin - Sorghum halepense (L.) Pers.
Johnson grass (A - infestation in field; B -
large whitish rhizomes produced after plants head out).
- Ontario Weeds Act - noxious
Other provinces - none
Canadian Federal Seeds Act - Class 2
U.S. Federal Noxious Weed - no
U.S. Noxious State Reg - 26 states (including
Mich, Ohio, Indiana, Illinois, Minnesota, Penn)
- Pub 505 - no
NE Weeds - no
Canadian Poison Plant - 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).
Cornell Poison Plant - referred to Canadian
Indiana Toxic Plants: TOXICITY RATING: Moderate
to high. ANIMALS AFFECTED: All types, especially ruminants.
DANGEROUS PARTS OF PLANTS: Leaves and stems, especially young
plants. CLASS OF SIGNS: Breathing problems, staggering, severe
anxiety, convulsions, coma, death (may be very sudden).
- Not commonly found in Ontario. Does not usually overwinter
in Ontario but occasionally found overwintering in protected areas
such as near woodlots or river valleys.
- Difficult to control and very competitive with row crops such
as corn and soybeans.
- Johnson grass has been reported to be a source of aster yellows
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