The Cross Section, Volume 32, Number 8, August 1986 Page: 2
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Page 2 THE CROSS SECTION August 1986
AUTHENTICATION OF WEED LOSS ESTIMATES IN TEXAS COTTON
JOHN R. ABERNATHY and J. W. KEELING
Texas Agricultural Experiment Station, Lubbock, TX 79401
Annual field surveys and estimates have been made to determine losses
in cotton production due to major weed species. For each weed, yields of
weedy and weed-free cotton were calculated at four locations in each of two
counties of the Texas High Plains.
Greater losses from weeds were documented by field surveys as com-
pared to estimates in 1979 and 1980. Field survey losses were more closelyrelated to estimated losses in 1981-85. In 1983, 1984 and 1985 greater
field survey losses were documented from Johpsongrass and woollyleaf bur-
sage as compared to estimated losses. Losses due to pigweed were less in
the field survey. In 1985, cotton losses due tp weeds were about the same
as in 1984. The greatest losses of cotton in 1985 were caused by pigweed,
silverleaf nightshade, Johnsongrass and woollyleaf bursage. For all other
species, estimates and field survey losses were closely related. The following
table lists the estimated and surveyed yield percentage reductions for 11
important weed species.Weed
Pigweed .................. .....
Johnsongrass .............. ......
Lanceleaf Sage ...................
Woollyleaf Bursage ...............
Silverleaf Nightshade .............
Yellow Nutsedge ........... .....
Cocklebur ..................... .
Morning Glory ...................
Prairie Sunflower ................
Field Bindweed ..................
Barnyard Grass ..................1979 1980
Esti- Field Esti- Field
mated survey mated survey
4.0 9.0 2.9 1.7
* 0.5 2.5 0.7 2.0
0.2 2.4 0.5 1.3
0.1 1.4 0.1 1.0
2.0 18.4 1.5 5.9
* 0.2 0.3 0.3 1.0
S 0.1 1.1 0.3 1.2
0.1 3.0 0.4 2.1
0.1 8.4 0.2 1.1
0.2 0.7 0.2 1.5
0.1 1.1 0.1 0.7% Yield Reduction
1981 1982 1983
Esti- Field Esti- Field Esti- Field
mated survey mated survey mated survey
2.5 2.4 2.5 1.2 2.3 0.4
0.1 0.5 0.6 3.9 0.5 2.3
0.1 0.4 0.1 1.3 0.1 0.6
0.1 0.3 0.1 1.1 0.2 1.3
1.3 0.3 1.3 1.5 1.2 1.2
0.4 0.1 0.4 0.2 0.4 0.2
0.4 0.2 0.4 0.3 0.4 0.4
0.3 0.2 0.3 0.4 0.4 0.3
0.2 0.1 0.2 0.1 0.2 0.1
0.1 0.1 0.1 0.2 0.1 0.1
0.3 0.1 0.1 0.1 0.1 0.1WEEDS . . .
continued from page 1
occurs when producers plow through
spots that are heavily infested with
these perennial weeds. When you plow
through infested areas, you are drag-
ging roots into fresh areas.
"This is especially noticeable when
you can drive around the edges of
playa basins that have been cultivated
and the lakeweeds drug out into the
fields. The lakeweeds are getting more
widespread each year and literally tak-
ing over in some areas. It is important
to realize that and try to limit cultiva-
tion through these spots," he continues.
"A combination of all this is making
this problem worse. That would be my
best guess as to why our perennial
weed infestations might be getting
worse," Keeling states.
Now's A Prime Time For Control
In general terms, Keeling states that
weed control has become a little more
sophisticated. "There are specific treat-
ments for specific weed problems,"
Keeling says. However, he basically
advises all applicators to read the label
directions and use herbicides according
to those directions to obtain the most
effective control of perennial weeds.
Additionally, the optimum time for
applying herbicides and tackling peren-
nial weed problems is from the middle
of August through the fall.
With most cotton crops established,
producers may have time now to con-
centrate on treating perennial weeds.
"In general terms we can get better
results dealing with perennials, the
weeds that come back from the roots,
late in the summer and into the fall.
They are more susceptible to herbicidal
control now as opposed to early in the
season. For best results, the plants need
to grow into the late summer or fall
to get the most from your dollar inHerbicidal Controls Available
With silverleaf nightshade or white-
weed, Dr. Abernathy's TAES weed re-
search of several years has found that
the best treatment is a broadcast, rope-
wick or spot spray application of
Roundup on mature whiteweed plants.
"If Roundup is applied in the right way
and at the right time, a 90 percent
control of whiteweeds can be ob-
tained," Abernathy explains.
"Blueweed is a little more difficult.
With blueweed good results can be
achieved with applications of one to
two quarts per acre of Banvel. Through
this treatment, combined with tillage
the next summer and then retreatment
with Banvel, we are able to reduce the
blueweed spots from cotton," con-
tinues Abernathy.
Banvel at one to two quarts per acre
is also an effective treatment for lake-
weed. With this treatment, producers
can suppress lakeweed until the next
year, but erradication is more difficult.
MSMA provides effective burn-down of
lakeweed when applied prior to cotton
planting.
New Materials For Control
Both Keeling and Abernathy are in-
volved in the weed research program
at TAES, looking at all new chemicals
on the crops and weeds grown in this
area to see how they might offer better
control of weeds. Additionally, chemi-
cals that are designed for other weeds
and crops are evaluated on the specific
weeds and crops that are predominant
in this area.
"Within any one year we will have
50 to 60 weed experiments, each one
having 20 to 50 different treatments,
looking at specific crops or weeds on
different soil types," states Keeling.
There are several new chemicals that
have proven successful in previous"Another herbicide being investi-
gated, that is not commercially avail-
able, is called Reflex. Reflex may be
applied to the soil before cotton is
planted, and it will provide good to
excellent control of lakeweed. Field
use of this chemical is at least a couple
of years down the line though."
Landowners Need To Be Involved
In these tough economic times, land-
owners may need to become involved
and perhaps buy some chemicals or go
into some cost-share arrangements with
their tenants on rented land.
Keeling remarks, "On a yearly basis,
it may not pay the operator to go out
and spend from $20 to $40 per acre
on herbicides. The tenant may bebetter off losing production from the
infested acreage. But, when you look
at it over a 10-year period, or in terms
of preserving the value of the land for
the future, there is more of a long-
term b nefit than a short one. So we
need o look at the investment of
herbicides for perennial weed control
as a long-term investment."
"Lakeweed has the most potential for
infesting more acres and really reduc-
ing the productivity of the farm than
most qf the other perennial weeds we
have," Inotes Abernathy. "If lakeweed
takes over, it can make the land worth-
less, because no crop can compete with
lakeweed and produce a normal yield."
--KRAvoid Potential Farm Hazards
Irrigators are usually very cautious direct current running through the
when dealing with potentially dan- equipment. Irrigators should con-
gerous farm equipment. However, tact qualified professional help for
accidents do happen. The following repair to avoid electrical shock.1984
1985
Esti-
mated
.2
0.4
0.3
0.2
1.1
0.4
0.4
0.3
O.1
0.1
0.1Field
survey
1.8
2.3
0.5
1.2
1.1
0.2
0.4
0.4
0.1
0.1
0.2Esti-
mated
1.4
0.4
0.2.
0.3
1.1
0.4
0.4
0.3
0.3
0.1
0.1Field
survey
0.9
1.5
0.4
1.1
1.3
0.2
0.2
0.2
0.1
0.1
0.1terms of treatment," Keeling says.
The most common perennials in this
area, according to Keeling, are silver-
leaf nightshade or whiteweed, Texas
blueweed and woollyleaf bursage or
lakeweed. "Additionally, Johnsongrass
and bermudagrass are still problems in
a lot of areas," Keeling adds.experiments. Keeling notes, "Arsenal,
which is registered for use on non-
cropland areas, looks very effective on
lakeweed. Arsenal prevents cotton pro-
duction for two to three years, but will
control lakeweed for that period of
time. This herbicide has not been
Looked at long enough to know
whether the lakeweed will regrow
when that time period has passed.Irrigators are usually very cautious
when dealing with potentially dan-
gerous farm equipment. However,
accidents do happen. The following
tips are offered to help irrigators
avoid some possible risky situations
and to help keep irrigation water
management as safe as possible.
* Don't go near the unprotected
drive shaft on your internal com-
bustion engine, it can be poten-
tially fatal. The drive shafts com-
monly found on irrigation wells
rotate at 1750 revolutions per
minute. Accidents may occur
when a shirttail or sleeve gets
caught on one of the U-joints
located at either end of the shaft.
In just a fraction of a second, the
clothing winds around the spin-
ning shaft and the results are
usually very serious. To avoid
these hazards, place a guard or
shield over the shaft.
Check electrical equipment to
assure that it is properly grounded
prior to using it. An electrical
tester provides a simple, effective
way to check electrical equipment
for voltage that may be passing
through it before an accident hap-
pens. A reading on the electrical
meter indicates that there is adirect current running through the
equipment. Irrigators should con-
tact qualified professional help for
repair to avoid electrical shock.
Electrical testers are commonly
available from your local electric
supply store.
Check for loose and exposed
wires in all electrical equipment.
Watch for highline wires when
moving portable aluminum pipe.
Unfortunately, m a n y irrigators
have been severely injured when
they tried to shake a rabbit or
other small animal out of a section
of aluminum pipe and the pipe
accidentally came in contact with
an overhead highline wire.
Check the wires on your center
pivot. Shorted out wires will
cause the entire pivot to be "hot,"
sending 440 volts of electric cur-
rent down the pivot.
Make sure your center pivot and
the electric pump panel boxes are
properly grounded. If the boxes
are not properly grounded, they
may be "hot" even when turned
off. Also the wires may weather
and fray or cattle may disturb the
wires, which can make the box
dangerous. -BSPage 2
T HE C R OSS S EC T IO N
August 1986
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High Plains Underground Water Conservation District No. 1 (Tex.). The Cross Section, Volume 32, Number 8, August 1986, periodical, August 1986; Lubbock, Texas. (https://texashistory.unt.edu/ark:/67531/metapth1533137/m1/2/: accessed July 11, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu.; crediting UNT Libraries Government Documents Department.