Cultural
Control |
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Strategies
Click
on each individual control method to learn more about each
factor.
- Use
crop rotations that extend the period between winter grain
crops to at least three years.
- Plant
certified or jointed goatgrass-free seed.
- Delay
seeding in the fall.
- Plant
tall, fast growing winter wheat varieties.
- Plant
wheat at recommended or above normal seeding rates and in
narrow rows.
- Maintain
healthy, vigorously growing winter wheat.
- Apply
fertilizer so that it is available to the wheat, not the
goatgrass.
- Prevent
new seed production in fallow, readsides, or waste areas.
- Properly
adjust the combine.
- Use
tarps to cover trucks during grain transport.
- Do
not transport contaminated straw to goatgrass-free areas.
- Grind
contaminated grain before feeding to livestock.
- Deep
plow fields in late fall or early spring once every 5 or
6 years.
- Burn
wheat stubble to kill most JGG seed on the soil surface.
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1.
Use crop rotations that extend the period between winter grain
crops to at least three years. |
| In
predominately winter wheat-fallow areas, this can be accomplished
by switching one year to a spring wheat. Because the soil
is moist in early spring, tillage by itself will not kill all
of the jointed goatgrass. Therefore, infested fields should
be sprayed with glyphosate several weeks before they are tilled.
Consider rotating with late spring-planted warm season crops
such as corn, grain sorghum, proso millet, or sunflower.
Cool-season crops such as spring wheat and spring barley must
be planted early to give them time to germinate and produce
seed. The use of tillage
was once thought to enhance jointed goatgrass germination
after wheat harvest and during fallow periods. Recent
studies in Kansas indicated that no differences in JGG germination
were seen for mechanical fallow (tillage) or chemical fallow
(herbicides; no-till) during most years. However, using
tillage in fallow during a dry season may promote more JGG
germination compared to using only herbicides. The thought
behind this is that tillage provides better soil seed contact
and allows the JGG seeds to better access subsurface soil
moisture compared to using only chemicals (no-till).
In addition, western Kansas typically receives enough rainfall
during germination periods in the fall and spring to promote
JGG emergence in no-till, chemical fallow fields. Keep
in mind that this practice may not work for all regions where
jointed goatgrass is a problem.
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2.
Plant certified or jointed goatgrass-free seed. |
Certified
seed will assure growers their seed source is not contaminated
with jointed goatgrass spikelets. Contaminated seed is
likely the primary source of new jointed goatgrass infestations.
If using bin-run or brown bagged seed, always check to
be sure your seed is free of jointed goatgrass.
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3.
Delay seeding in the fall. |
If
a rain occurs near planting time, wait a few days for the jointed
goatgrass seed to germinate. Use tillage or non-selective
herbicides to kill goatgrass seedlings before planting wheat.
Delaying the time of planting may allow more jointed goatgrass
seedlings to emerge and be controlled. Following planting,
the ideal scenario would see winter wheat emerge several weeks
before the next flush of jointed goatgrass seedlings.
Delayed emergence relative to winter wheat will reduce competition
from jointed goatgrass. A Colorado study showed that 15
jointed goatgrass plants per square yard reduced wheat yields
27% when it emerged with winter wheat, 17% when it emerged 42
days later, and 6% when it emerged in March, 150 days after
winter wheat. Similar studies showed that delayed emergence
of jointed goatgrass dramatically reduced jointed goatgrass
tiller and spikelet production. With less competition,
winter wheat yields were generally greater when jointed goatgrass
emergence was delayed for several weeks or months.
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4.
Plant tall, fast growing winter wheat varieties. |
The
tall characteristic alone will not ensure the maximum competitive
advantage for the crop. Varieties that are most competitive
will emerge quickly, have rapid shoot and root growth, and constantly
shade jointed goatgrass throughout the growing season.
Soil moisture and early growth rate are important factors for
crop competitiveness. A USDA-ARS study in Washington state
showed that some varieties are more competitive with jointed
goatgrass than others. This study also demonstrated how
jointed goatgrass is much more competitive with winter wheat
under dry conditions.
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5.
Plant wheat at recommended or above normal seeding rates and
in narrow rows. |
Higher
plant populations can increase crop competition with goatgrass.
Producers in high rainfall areas may see increased competition
with little risk to wheat yield. However, low rainfall
areas may be precluded from increasing seeding rates due to
a higher risk of reduced yields and test weights. Winter
wheat seeding rate should not be below the recommended rates.
Narrow row spacing can also increase crop competitiveness.
High seeding rates and narrow row spacing will not always increase
yield, but when combined with other cultural practices including
a tall, fast growing variety will minimize jointed goatgrass
competition and weed seed production.
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6.
Maintain healthy, vigorously growing winter wheat. |
A
healthy crop can be the most effective and economical weed control
practice. Crops suppress weeds primarily by shading.
Management strategies that hasten shading of weeds will ultimately
lead to a more competitive crop and less weed seed production.
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7.
Apply fertilizer so that it is available to the wheat, not the
goatgrass. |
Research
in Wyoming has showed that jointed goatgrass was most competitive
when fertilizer was broadcast applied compared with banding
or spoke-wheel injection. Jointed goatgrass likely profits
from the broadcast treatment because it usually germinates in
the top inch of soil where broadcast fertilizer is readily available.
Placing fertilizer deeper into the soil profile allows winter
wheat roots to access the fertilizer more quickly and fully
than jointed goatgrass roots. Research in Colorado suggested
that timing of fertilizer application is important for reducing
the impact of annual grass weeds in a winter wheat-fallow rotation.
These studies showed that a fertilizer application in April
of the fallow season, rather than at fall planting, favors winter
wheat over annual grass weeds. Nitrogen applications in
the spring of the fallow season leach deeper into the soil profile
than nitrogen applied later in the season. This deeper
nitrogen is less available to surface germinating weeds, such
as jointed goatgrass and downy brome, than to winter wheat.
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| 8.
Prevent new seed production in fallow, roadsides, or waste areas. |
Hand
rogue scattered plants or use non-selective sprays to kill small
patches before the weed produces viable seed. Timing of
jointed goatgrass control is critical for eliminating seed production.
Jointed goatgrass should be controlled before flowering (anthesis)
to prevent seed production. A study in the Pacific Northwest
showed that mowing or treating JGG seed heads (50% emerged from
the flag leaf) with glyphosate or paraquat eliminated viable
seed production. However, gradual delays in treatment
timing after flowering resulted in progressively higher numbers
of viable goatgrass seed produced. For very late goatgrass
control, paraquat or mowing may be preferred over glyphosate,
which kills the plant more slowly and may allow more viable
seed to develop. Treatments of paraquat or mowing at early
post-anthesis, reduced seed production to less than 20% of the
glyphosate treatment. Clean combines and other machinery
before entering goatgrass-free fields.
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| 9.
Properly adjust the combine. |
Proper
combine adjustment can help in removing additional JGG seed
from the field. This is purely up to the individual!
You need to decide if it is more important to deal with added
JGG seed to the field or if removing as much as possible would
benefit you in the long run. These are some issues that
one needs to consider if total crop failure is evident.
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| 10.
Use tarps to cover trucks during grain transport. |
The
lightweight spikelets, which are easily confused with wheat
straw, can blow off the truck and start new infestations.
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| 11.
Do not transport contaminated straw to goatgrass-free areas. |
This
point really needs no explanation.
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| 12.
Grind contaminated grain before feeding
to livestock. |
Run
contaminated grain through a hammer mill before feeding to livestock.
A Nebraska study showed that 20% of goatgrass spikelets germinated
after 24 hours of rumen digestion. Spikelets processed
through a fin-grind hammer mill before feeding eliminated goatgrass
germination. Chemical analysis of jointed goatgrass spikelets
showed that protein content was 11.7% and crude fiber was 26.1%.
A study in Oklahoma showed that when cattle were allowed to
graze wheat in the fall, jointed goatgrass seed production increased
and wheat yields decreased by 20%.
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| 13.
Deep plow fields in late fall or early spring once every
5 to 6 years. |
| About
90% of JGG seedlings emerge from the top inch of soil, whereas
very few emerge from below 3 inches. This may be one reason
why jointed goatgrass seems to flourish under shallow tillage
compared to deep tillage. Compared to sweep tillage, moldboard
plowing has reduced populations in the following crop by 60%.
Frequent plowing may only serve
to bring more goatgrass seed to the surface. Deep plowing
helps bury jointed goatgrass seed to the point where seedlings
have a hard time emerging. However, one has to think
about possibly promoting germination during fallow periods
to reduce the amount of JGG seed already in the soil.
This is obviously a management decision that needs to be made.
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| 14.
Burn wheat stubble to kill most JGG seed on the soil surface. |
| For
burning to destroy jointed goatgrass spikelets, there must be
enough surface residue to sustain high temperatures and straw
must be uniformly distributed. Post harvest burning of
wheat stubble during dry field conditions has killed 90% or
more of the goatgrass seed lying on the soil surface.
Spikelets in soil cracks and or covered by a thin layer of soil
may not be destroyed. Because of air pollution and the
potential for soil erosion following the loss of straw cover,
burning should be restricted to small, isolated goatgrass infested
areas. Large areas of wheat stubble should be burned only
as a one-time event as part of a long-term management program
that includes other cultural control practices such as a temporary
change in crop rotation. |
