Rory Lewandowski, Extension Educator Wayne County
Mark Sulc, Extension Forage
Specialist
Many
cow/calf beef enterprises across the state utilize tall fescue as their primary
pasture forage. In most instances, it is
Kentucky 31 endophyte infected forage, and while this is a great option for a
late fall and winter stockpiled forage, there are some significant downsides to
using this forage during the growing season, particularly summer. The endophyte is a fungus, specifically Neotyphodium coenophialum and it is
responsible for multiple livestock disorders including fescue foot, bovine fat
necrosis and fescue toxicity. Fescue
toxicity is the most common disorder and is associated with poor animal
performance characterized by reduced feed intake, decreased weight gains,
lowered milk production, lowered reproductive performance and rough hair coat.
Last
summer’s drought may have inadvertently created an opportunity for some beef
cattle graziers to reevaluate the tall fescue mix in their pastures. Pastures that were overgrazed during the
drought and into the fall period are likely to have “holes” where desirable
grass species have dropped out and where weeds may have or will be filling
in. Even those endophyte infected tall
fescue pastures could be thinned out; although it is likely the tall fescue
will recover and survive. However, these
pastures can benefit from renovation.
We are now
past the point where frost seeding and broadcasting seed is a viable
option. April is a good month to do some
no-till drill pasture renovation work.
One of the commonly employed strategies to reduce the effects of fescue
toxicity is dilution with other species in the pasture. Endophyte infected tall fescue pastures can
benefit from renovation when other species, particularly legumes, are added to
the pasture mix. Generally red and white
clover can work well as legume species in a tall fescue stand. The goal should be to establish a 30 to 35%
clover mix evenly distributed throughout the fescue pasture. The no-till drill should be adjusted to
insure that seed is not placed more than one-quarter to one-half inch deep.
If weeds are present or the tall
fescue sod is vigorous then something must be done to reduce this competition
and give the new seedlings a chance to establish. The most effective option may be the use of a
chemical herbicide. Always read and
follow the label directions regarding rates and possible intervals between
application and planting a new crop/seed.
Gramoxone can be used as a burndown to provide time for the new seeding
to become established. Non-chemical
methods include mowing at very short heights or grazing the cover down tight to
suppress the grass sod.
There may be situations where
eradication of an endophyte infected tall fescue pasture is a better option
than renovation and the dilution strategy.
Right up front I will say that this is not an easy task and in order for
this to be successful it takes a commitment of time and management. According to some tall fescue management fact
sheets from the University of West Virginia and the University of Arkansas,
this is a process that will take 1 to 2 years and requires steps to kill the
endophyte infected stand, prevent the reintroduction of endophyte infected seed
and then continued to management of the new seeding. This process is more likely to have success
if there is a pasture field where some tillage machinery can be used.
Although there are variations to
this process, if eradication is going to start in the spring, these steps
should be followed:
·
Soil test to determine if lime, phosphate or
potash needs to be added to bring the field to critical soil levels. Those levels are a soil pH of 6.5, a
phosphate level of 25 ppm and a potash level of 120 ppm or according to the
formula of: 75 +(2.5 x C.E.C.).
·
Kill the existing tall fescue sod. Generally glyphosate is the most commonly
used herbicide for this purpose. If the
sod can’t be sprayed until late April or early May, then the pasture must be
clipped to prevent any seed head formation.
·
If lime or fertilizer is needed to correct soil
deficiencies, till the field and incorporate the lime and fertilizer 6-8 inches
deep.
·
Plant a warm season annual crop such as pearl
millet, sorghum x sudangrass or sudangrass when the soil temperature reaches 60
to 65 degrees F. These are vigorous,
tall growing forages that will act to smother out any fescue that might
germinate. These crops can be used for
summer grazing. Another option would be foxtail millet, which would make a
single hay crop by late summer (and would not require killing after the single
hay crop)
·
In late August or early September kill off the
summer annual using glyphosate (not necessary if foxtail millet is used). This
glyphosate application is another opportunity to kill any surviving tall fescue
plants.
·
Till the field and prepare a seedbed to plant a
winter annual crop such as winter wheat or winter rye. No-till planting is also appropriate. This crop can provide some late fall grazing.
·
The next year, depending upon the spring, take a
final grazing pass or remove the winter annual as wet wrapped baleage. Take time to walk over the field. If any fescue is observed, apply another
application of glyphosate. In mid to
late April plant the field with a perennial pasture mix that includes grass and
legume species.
After this time period removed from
tall fescue seed head production, any tall fescue that emerges from old seed in
the soil should no longer contain a viable infective fungus. A fact sheet on endophyte toxins from Oregon
State University says that the fungus will lose its viability if stored for 18
or more months. Other sources say 12
months is enough for the fungus to lose its viability in stored seed.
Finally,
even if eradication is successful, the grazier must continue to manage to
prevent endophyte infected seed from being re-introduced into the field from
machinery and/or animals carrying viable seed in their digestive tracts from
endophyte infected fields. Infected tall fescue can also be reintroduced by
feeding hay of endophyte-infected tall fescue containing seed heads with viable
seed.
References:
Aldrich-Markham,
S., Pirelli, G., Craig, A., Oregon State University “Endophyte Toxins in Grass Seed Fields and
Straw Effects on Livestock”
Ball, D., Schmidt, S., Lacefield, G., “Tall Fescue Endophyte
Concepts”
Jennings J., West C., Jones, S., University of Arkansas, “Friendly
Endophyte-Infected Tall Fescue for Livestock Production”
Rayburn E., West Virginia University, “Tall Fescue
Management”
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