Everglades Station Mimeo Report 63-15
RANCHERS : KILL BUTTERWEED NOW !
J. R. Orsenigo, Ralph W. Kidder and R. J. Allen, Jr.-
Kill butterweed now! If you don't, it may kill your cattle later. Ask
yourself these questions: Do I have bright-green, cold-resistant, rosette
plants in my frozen pastures? Do my cattle graze them? Will these animals die?
The Problem: After pastures freeze and grass is scarce, ranchers occa-
sionally find sick or dead cattle and wonder what is wrong. For more than 10
years, researchers have observed and studied one of the causes, "Butterweed",
Senecio glabellus2/. Cattle sickness and death have occurred when Senecio was
present in pastures that were thin and lacked sufficient forage in winter and
The Symptoms: Effects of apparent Senecio-poisoning include aimless walk-
ing, circling and staggering in the early stages. Nearly all affected animals
die. Veterinarians can verify the diagnosis from internal symptoms. Liver
damage is usually too extensive to permit recovery by the time outward symptoms
appear. No cure or corrective treatment is known. Symptoms may not be observed
until 1 or 2 months after grazing the weed.
The Weed: Butterweed is a winter-spring annual found in the entire South
Florida area on flatwoods pastures as well as sand and muck soils around Lake
Okeechobee and southward. Seed germination and plant growth follow periods of
cold weather especially when competition with pasture grasses is least. Any-
thing that reduces grass density in pastures permits butterweed to grow. Ini-
tially, the plant's bright green leaves form a rosette or wheel-spoke pattern
close to the ground. Later, a seed stalk with few, small leaves develops from
the center of the rosette to a height of one to several feet after which the
bright yellow flowers open. A thread-like hair attached to the small seed helps
spread the weed by wind. Butterweed dies after flowering. Few plants are found
The Toxic Agent: Several alkaloids poisonous to cattle are found in most
Senecio species. Preliminary data developed cooperatively with Dr. W. M. LauterY/
indicate that similar total alkaloid levels are found in different plant growth
stages as well as in plants collected from several locations. The toxic agent
is found in very low concentration but, apparently, cattle bec ed after
eating small amounts of the weed. The rate of grazing the S' 5n1fsi-
bility of cumulative toxic effects from repeated feeding u o ddly det ne
when cattle show symptoms. 5
The Preventive Measure: The only positive method o p event~ catt
poisoning is to keep butterweed out of pastures with a goo nagemed ro. m
supplemented by herbicides when needed.
1/ Associate Horticulturist, Animal Husbandman and Assistant Agronomist,
respectively, University of Florida, Everglades Experiment Station, Belle
2/ A synonym used earlier was Senecio lobatus
3/ College of Pharmacy, University of Florida, Gainesville, Florida.
The Management Program: Few weeds arise under good systems of pasture
management. Overgrazing, inferior pasture grasses, low fertility, lack of
clipping and general neglect reduce pasturage and lead to weedy pastures,
especially with butterweed in late winter and spring. Naturally, prolonged
cold, wet periods and freezes thin the pasture grass, thus reducing forage
quality and stocking capacity. If forage is scarce, a pasture supplement
should be provided.
The Chemical Program: Butterweed can be controlled with chemicals known
as herbicides. Actively growing weeds are most readily killed by herbicides.
Recommended procedures are as follows:
1. Unless forage is very short or butterweed very thick,
do not spray pastures until the biggest butterweed plants make a
rosette about 10 inches in diameter.
2. Apply 2,4-D (amine salt or low-volatile ester) at the
rate of 1 to 1-1/2 lb/A. acid equivalent (1 to 1-1/2 quarts of a
4 lb/gallon formulation). The 2,4-D should be sprayed in 10 to 30
gallons of water per acre with flat-fan "weed" nozzles at low
pressure (10 to 30 psi).
3. If sprays are applied in February, it may be necessary
to spray again in late March or April if additional seed germinate
and new plants come up.
4. It is desirable to remove cattle before spraying pastures
and to hold them off for about a week. Remove cattle if they eat
dying or dead butterweed.
5. Apply 2,4-D with appropriate caution if pastures are near
vegetables or other sensitive crops.
6. Consult your county agent, experiment station or veterinarian
for additional information.