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ERGOT
RISKS IN TALL FESCUE
by
Paul Vincelli
May, 2008
The ergot fungus, Claviceps
purpurea, is a widespread
fungus that attacks the flowers of a number of grass species.
The ergot fungus infects only the flower parts of certain grasses, and
replaces the seed with "ergots". Ergots are survival bodies of the
fungus that are easily recognized with the naked eye. They look like dark brown
to black, curved miniature cigars measuring 1/8 inch to 3/8 inch. They are
longer than grass seed, so they stick out beyond the glumes (Figure 1). If you
cut them open, you'll see that they have a gray to whitish interior. These
ergots will be evident as the seedheads approach maturity.
Tall fescue is commonly affected in Kentucky, though other grass species
may also be attacked.
C. purpurea is related
to the fungal endophyte of tall fescue, and both are capable of producing potent
toxic alkaloids that affect animal health (and human health, if eaten). This is
not a trivial issue; I once was subpoenaed to give a deposition in a case in
Kentucky with economic losses of over $2 million, in which ergot was implicated
as the cause. And in the past few
weeks, there was a case of poisoning of livestock in Wisconsin when bedding
composed of ergot-contaminated tall fescue seed hulls was used.
Management
Preventing livestock from consuming a significant dose of ergot sclerotia is the
only reasonable course of action.
·
Pasture
If seedheads form, inspect them for ergots. If they are found, mow before
turning livestock out into the pasture. Mow the seedheads along the fencerow, as
well.
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Hay
If the seedheads are dry before harvesting, the ergots will often fall to the
ground during cutting/tedding/baling. However, if the seedheads were still
somewhat green when cut, the ergots can remain attached to the seedhead, and
will end up in the bale. In harvested hay, ergots constitute a very small
fraction of the total forage in the bale. Because of this, the risk from feeding
these bales is low. However, repeated feeding of infested hay into a feedbunk
can lead to accumulation of the ergots at the bottom of the bunk. Livestock may
then consume a high dose of ergots when they feed on this residue.
·
Seed Production
Where tall fescue is being grown for seed, avoid exposing livestock to the
screenings and seed hulls, as these may be contaminated with ergots.
Seed-cleaning operations concentrate the ergots and can pose a great hazard if
livestock consume them.
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