THE TEXAS AGRICULTURAL EXPERIMENT STATION

m

BULLETIN

/J. E. Miller, Director/ Texas A&M University/ College Station, Texas

B-1158
November 1975

WEED CONTROL RESEARCH IN SUGAR BEETS
A. F. Wiese, P. R. Scott, D. E. Lavake, S. R. Winter and D. F. Owen*

Total sugar beet acreage in the Texas Panhandle
has varied from 20,000 to 40,000 acres since Holly
Sugar Corporation started operations in 1964.
Ineffective weed control methods and high hoeing
costs, excessive nitrogen fertilization, and leaf spot
disease have created problems for sugar beet
producers. Weed control methods that have been
satisfactory for other sections of the country have not
been consistently effective in West Texas.

Since 1964, herbicide treatments and cultural
practices have been evaluated for controlling weeds
in sugar beets grown in the Panhandle of Texas. Prior
to planting, herbicides were either injected or
sprayed on dry beds and power incorporated. After
emergence, herbicides were applied at various stages
of weed and sugar beet growth, and herbicides were
incorporated into the soil at layby. Various
combinations of herbicide application and cultural
practices were made to find the most effective weed
control procedure. This research has been a
cooperative effort among The Texas Agricultural
Experiment Station and USDA Agricultural Research

*Respectively, professor, The Texas Agricultural Experiment
Station, Bushland; agronomist, Holly Sugar Company, Hereford;
technician II and assistant professor, The Texas Agricultural
Experiment Station, Bushland; and agronomist (formerly) Texas
Tech University Center, Amarillo, (presently) The Texas
Agricultural Experiment Station, Halfway.

Mention of a trademark or a proprietary product does not
constitute a guarantee or a warranty of the product by The Texas
Agricultural Experiment Station and does not imply its approval to
the exclusion of other products that also may be suitable.

Service, Bushland; Holly Sugar Corporation,
Hereford; Texas Tech Center, Pantex; and farmers in
the Panhandle.

Preplant Incorporation

The effectiveness of preplant herbicides
improved as average temperature increased. Pyramin
and Tillam gave little weed control in March when
sugar beets are normally planted but worked well
when applied in May. Pigweed control with Pyramin
and Tillam increased as thoroughness of
incorporation increased. CP45592 and CP52223 gave
acceptable weed control, but development of these
herbicides was discontinued by the manufacturer
because of chemical injury to sugar beets in other
parts of the country. Good weed control was obtained
with 11913, but serious injury to sugar beets occurred
in 1 year of the 3 this herbicide was tested.

Preplant Injection

Eptam was the most effective herbicide tested as

a preplant injection. Injury to sugar beets was
moderate. Treflan and Planavin gave fair control
without causing crop injury. Injection of Pyramin and
Tillam into dry beds was more economical and
effective than being sprayed on dry beds and power
incorporated.

Postemergen ce

Postemergence herbicides available before 1968
gave erratic results. Pyramin Plus controlled pigweed
in the cotyledon stage but was not effective if weeds
were larger or soil was dry. Other postemergence

The complete report, B-1158C, ”Weed Control Research in Sugar Beets” with an appendix, 12 tables and 4 figures, is
available from Research Publications Editor, Department of Agricultural Communications, Texas A&M University, College

Station, Texas 77843. Allow one month for delivery.

herbicides that controlled pigweed and kochia
sometimes caused severe injury to sugar beets.

Since 1968, Betanal has been very effective
against small kochia and Betanal-475 very effective
against pigweed. Each herbicide has been effective
against very small barnyardgrass. Good control of all
three weeds has been obtained from a 50-50 mixture
of the two herbicides. Betanal mixed with Dowpon
eliminated pigweed and controlled more than 8O
percent of the barnyardgrass but was somewhat
injurious to sugar beets.

In 1970 and 1971, several postemergence
herbicides were applied to sugar beets and weeds at
two stages of plant growth. Betanal gave the best
control of kochia. Small weeds at the first stage were
most easily killed. Kochia was not controlled with any
treatment at the second application. In 1971, small
pigweed and a few kochia were nearly eliminated
with Betanal-475, Betanal + Dowpon, SN 503, and
Nortron. When pigweed were larger, only Betanal,
Betanal-475 and a mixture of Betanal and Dowpon
gave good control. In 1970, when soil was dry, sugar
beets were not stunted or injured at either stage of
growth. In 1971, when sugar beets were small and the
soil was wet, early season injury was evident with
Betanal + Dowpon and Nortron. Sugar beets
outgrew any injury by August.

In 1969, a study was conducted to determine
whether two applications of postemergence
herbicides in 1 year were more effective against
pigweed and barnyardgrass than a single application.
An early application with Pyramin Plus and Betanal
resulted in better weed control than a later
application to larger weeds. When weeds were
double treated, control of both pigweed and
barnyardgrass was greatly improved. Sugar beet
injury was slightly increased, but plants recovered
before fall.

Injection and Postemergence

In 1969, several combinations of injected and
postemergence herbicides controlled weeds but
caused excessive injury to sugar beets. In 1971,

however, Eptam at 3 pounds per acre was the only
injection treatment that reduced beet stand. Nortron
was the most effective herbicide when injected at 3
pounds per acre and applied again postemergence at
an early stage. Postemergence treatments were more
effective against small than large weeds.

Preplant and Early Postemergence Injections and Layby
Incorporated :1
Compared with untreated areas outside of the

study, preplant injection application of Ro-Neet
reduced weeds from 20 per foot of row to about 4 per
foot of row. This reduced layby hoe time from about
35 hours per acre on untreated areas to 14 hours per
acre where Ro-Neet was injected. Early p
postemergence injection at first cultivation did not
affect weed population. Prior to applying layby
treatments, all plots were hoed. At harvest there was
about 1 weed in 10 feet of row where no layby
treatments were applied. Eptam reduced pigweed to
about 1 weed in 20 feet of row, and Treflan treatments
were almost weed free at harvest. Treatments did not
affect sugar beet tonnage or percent sugar; however,
when sugar per acre was calculated, differences
occurred. Neither high nor low yield was related to

j weed control obtained. Pigweed control obtained

after layby did not increase yield.

Conclusions

Since 1969, new experimental herbicides have
produced more effective weed control in sugar beets
than was previously possible. Ro-Neet has proved
more effective than Tillam for preplant injection and
preplant incorporation. Nortron at 2 to 4 pounds per
acre has given outstanding control of pigweed and
kochia when applied preplant and incorporated.

The best prospect for reducing hoeing costs in sugar
beets is to apply both a preplant herbicide and a
postemergence herbicide. Fields that are weed free at
layby can be kept clean with a broadcast-incorporated
application of Treflan.

KEYWORDS: sugar beets / weed control / herbicide / "l