Tansy Ragwort

We fight tansy every year, and if you let ONE plant go, you will be fighting hundreds in the years to come! What is it, and what can be done - read on!

Tansy ragwort (Senecio jacobaea)

Location
*   Found in drier regions of  Western USA, Europe, Asia,
and Siberia, where it can survive temperatures of -20 F
or lower.
*   Can withstand large variations in soil moisture
conditions and will tolerate the hot, dry summers
*   Can become established rapidly in forest clearcuts and can develop in irrigated, nonirrigated, and woodland pastures.

Plant Appearance
*  Conspicuous, daisy-like golden flowers, which appear over an extended period.
*  Rosette has irregular, lobed leaves, 5 to 9 inches long, attached directly to the main stalk.
*  Plant color is variable, ranging from light to dark green.

Lifecycle:
*  Tansy ragwort is a biennial,
but can develop as a short-lived
perennial.
*  Seeds can germinate in the
fall or spring.
*  The vegetative stage is a low,
dense, rosette.
*  Plants that emerge early in the fall and develop a rosette before winter usually bloom during the following summer, produce seeds, and die.
*  Plants that emerge late in the fall or in the spring are more likely to remain vegetative during the summer and bloom during the second summer.
*  If the plant is cut or broken
before it blossoms, it may
regrow and flower during
the third year.
*  Seed is the primary method
of ragwort dispersal. It is spread
by wind, water, and animals,
including humans.
*  Transportation of contam-
inated hay and straw from
western Oregon and Washington
by hunters is a major cause of
movement east of the Cascade
Mountains.
*  A single plant may produce 150
thousand seeds, which can remain
viable in the soil for 3 years or longer.
*  Most seeds do not move more than
a few feet from the parent plant.

Effects on Livestock and Horses
*  Livestock will not eat tansy ragwort if healthier forage is available.
*  Small plants, growing close to grasses and clovers or plants that have been baled with hay can not be picked out by livestock.
*  Tansy ragwort contains at least  6 pyrrolizidine alkaloids.
*  Concentration of alkaloids is greatest in :
     1) flowers
     2) leaves
     3) roots
     4) stems.
*  The alkaloids themselves are not toxic.
*  In the presence of certain liver enzymes, however, pyrrolizidine alkaloids are converted to pyrroles.
*  When enough conversion to pyrrole has occurred, the liver ceases to function normally and the animal dies. Liver damage builds up over time as the toxins are not flushed from the body. So removing animals from affected pastures is not enough to prevent poisoning, the damage may have already been done.
*  Cattle and horses are affected seriously; goats may suffer.
*  Pyrrolizidine alkaloids have been found in milk from cows and goats fed a diet containing tansy ragwort.
*  Susceptibility to tansy ragwort poisoning varies greatly among individual animals.
*  Livestock in poor body condition are most rapidly affected because of pre-existing liver conditions.

Getting Rid of Tansy
*  Tansy Decimated by the
Cinnabar Moth Larvae -
Small infestations can be
pulled by hand. The roots
must be pulled out for the
plant to die.
*  The large infestations
can be controlled with the
Tansy Flea Beetle, an
introduced biological
control agent, or the
Cinnabar Moth.

Comments from Pam:

We have quite a bit of tansy
on our property. We are
removing the plants this 
fall, but I wanted to wait
until I was able to get some
photos. Also, it was im-
portant to me not to disturb
the larvae feeding on the
plants or destroy the eggs
of the Cinnabar Moth.

Now that the insects have had their way, we will be digging up the plants and spraying roots with and herbicide to prevent and pieces left in the ground from regrowing.

Continuous monitoring of the pastures is needed in spring and fall to prevent a reinfestation since seeds can lay dormant for about 3 years. Seeds that have fallen will likely germinated and cause new plants.

Here are some photos of plants that are NOT tansy, but can be mistaken for it.
Dandilions and other yellow flowers.

When I was in 4-H we identified tansy by the flowers which generally have 13 petals. Dandelions have many more. Also, the leaves are larger than the plants pictured here.

This article may be reprinted on your web site if you include this entire paragraph when copying it to your site. Copyright 2004 - 2010, Pam Hunter, Hunter's Pony Farm http://www.huntersponyfarm.com