Klamath Experiment Station
Weed Control in Sugarbeets, 1997
K.A. Locke', K.A. Rykbost 2 , and R.L. Dovel 2
A
bstract
Weed control is a very important factor
in production of high sugarbeet yields
and quality. Previous research at Klamath
Experiment Station (KES) demonstrated yield
losses of 50 percent or more when weeds are
left unchecked. Growers have many control
options to consider, including preemergence
and postemergence products and at least six
different herbicides which can be applied in
various combinations. Efficacy of available
products vary for different weed species, for
stage of weed development, and in some
cases. for soil and environmental conditions.
With the range of factors involved that influence performance of herbicides, it is important
to conduct herbicide evaluations over several
years and locations. A total of 16 treatments
were included in replicated trials at KES and
one commercial field in the Henley area in
1997. Only data from the KES trial, which
included 11 treatments, is presented. All
herbicide treatments except one resulted in
significantly higher beet yield and gross crop
value than the untreated control. Weed competition in the untreated control reduced beet
yield to 58 percent of the trial mean. Several
treatments were significantly higher in yield
and value than a treatment which included two
postemergence applications of Betamix
Progress plus UpBeet. Among treatments that
have been evaluated for 3 years or more, the
highest sugar production and crop value has
been observed for postemergence combination
treatments using UpBeet, Stinger, and
Nortron. Weed control efficacy data were not
collected in the 1997 trial as weed pressure
was light and differences among treatments
were minimal.
Introduction
Chemical or mechanical weed control
in sugarbeets accounts for 20 percent or more
of variable production costs. Failure to adequately control weeds is probably the second
most important factor affecting profitability of
sugarbeets, after establishment date in the
short-season environment of the Klamath
Basin. Evaluations of various herbicides and
herbicide combinations have been conducted
at KES and in growers' fields since 1993.
Parameters of interest have included efficacy
for weed species, herbicide injury to crops,
and effects on beet yield, sugar content, sugar
production, and economic value. This report
summarizes effects of herbicide treatments on
crop performance in the 1997 KES trial and
compares performance for several herbicide
treatments evaluated in one to five years.
/ Klamath County Cooperative Extension Agent, Klamath Falls, OR.
2 /Superintendent/Professor and Associate Professor, respectively, Klamath Experiment Station,
Klamath Falls, OR.
1
Acknowledgments: Partial funding for the project is provided by the CBGA and E.I. du Pont de
Nemours and Co., Inc. Spreckels Sugar Company provided laboratory analyses of beet samples.
These contributions to the project are greatly appreciated.
82 Klamath Experiment Station 1997
Klamath Experiment Station
Weed Control in Sugarbeets, 1997
Procedures
The study site at KES was adjacent
to other sugarbeet trials in a field planted
to spring cereals in 1996. The variety
Bighorn was planted in 22-inch rows on
May 4. All cultural practices except for
weed control were as described on page
70. Beets were hand thinned to approximately 8-inch spacing on June 9. Individual plots were three rows wide and 22
feet long.
Treatments included an untreated
control, a hand-weeded control and nine
herbicide combinations (Table 1). Treatment combinations with preemergence
herbicides Pyramin and Nortron included
different rates and combinations of
postemergence products including
Betamix, Betamix Progress, UpBeet,
Stinger, Nortron, and Eptarn. The experiment was arranged in a randomized block
design with 4 replications of 11 treatments.
Chemical treatments were applied with a
CO, pressured backpack sprayer delivering
20 gpa of solution at 30 pounds per square
inch (psi) pressure. Preemergence treatments were applied May 7 and incorporated with 0.5 inch of irrigation water May
9. Preemergence treatments were applied
in a 7-inch band over the row.
Postemergence treatments were broadcast
applied May 21, when beet and weed
seedlings were mostly in the cotyledon
stage and on June 1, with the exception of
Eptam which was applied June 13 after
one cultivation.
Beets were harvested October 15 as
described on page 70. All beets from the
center row of each plot were counted and
weighed. Approximately 25-lb samples from each
plot were analyzed for tare loss and sucrose
content at the Spreckels Sugar Company Mendota
laboratory. Gross crop values were calculated for
each plot as described on page 70.
Results and Discussion
Under very favorable conditions,
sugarbeet seedlings and weeds began to emerge
within 6 days after planting. Sugarbeets developed rapidly and were more competitive with
weed seedlings than in earlier trials where beets
were stressed by wind and frost injury. All herbicide treatments provided relatively good control
of the weed species present at the site. Dominant
species included hairy nightshade, common
lambsquarters, redstem filaree, and shepardspurse.
Only minor differences were observed in weed
populations among chemical treatments and weed
counts were not taken.
All chemical treatments except one resulted in significantly higher beet yield than the
untreated control (Table 2). The combination of
Betamix Progress and UpBeet reduced yield
significantly (P = 0.05) compared with several
treatments. This appears to have been due to
injury to beet seedlings and reduced crop vigor
during the establishment period. Other treatments
that appeared to result in some crop injury included the combination of Nortron applied
preemergence with Betamix plus UpBeet applied
postemergence, and the treatment with only
Betamix applied twice postemergence. In part, the
yield reduction for the latter treatment may have
been due to inferior weed control in this case.
Hand weeding resulted in the highest beet yield,
followed closely by combinations of UpBeet,
Klamath Experiment Station 1997 83
Klamath Experiment Station
Weed Control in Sugarbeets, 1997
Stinger, and Nortron used postemergence.
Herbicide treatments did not affect sugar
content. Sugar yield was not significantly
different among the untreated control and
treatment numbers 5, 9, and 15. Treatment
numbers 2. 4, 8, 11, and 12 were not different
than hand weeding in sugar yield.
The grouping of treatments for gross
crop value was similar to that for sugar yield.
The treatment with Eptam applied at layby
may be an inexpensive alternative to the
postemergence combinations which are
relatively costly. The presence of difficult
weeds such as Russian thistle or kochia may
require adjustment of herbicide combinations.
Costs of products for the various
treatments are shown in Table 1. An estimate
of $150/acre for hand weeding is probably
representative of a modest weed infestation
situation. In early years of beet production,
some growers experienced costs of over $200/
acre for hand weeding. Average costs of
herbicide application are less than $10.00/acre
per application.
Data from KES weed control studies
conducted from 1993 to 1997 are summarized
in Table 3. Beet yield, sugar content, sugar
yield, and gross crop values are shown for all
treatments included in the 1997 study.
Multiyear comparisons among treatments are
made by converting parameters to percent of
the trial mean in each year, and averaging over
years. Thus, beet yield for the untreated
control averaged 63 percent of trial mean beet
yield over five years (Table 3). Statistical
comparisons between different years are not
valid.
84 Klamath Experiment Station 1997
Three treatments that produced high yields
over three or more years of evaluation include
combinations with UpBeet, Stinger, and
Nortron, and the treatment using Betamix
Progress (treatments 12 and 13, respectively). Treatment 13 is one of the least expensive
treatments. The only treatments with below
average performance were treatments 5 and
15, which were only evaluated in 1997.
Preemergence herbicides provide some
measure of insurance in situations where
weather conditions interfere with timely
postemergence applications. Based on only
one year, both Pyramin and Nortron were
acceptable for the sandy-loam soil conditions
at the lower application rate. Nortron at 3 pint/
acre caused crop injury. Preemergence treatments are relatively costly, but in some situations may help avoid a serious weed problem
if timely postemergence applications are
prevented because of weather conditions.
Treatment 8 shows promise as a cost effective
alternative in light weed pressure situations.
Klamath Experiment Station
Table 1. Herbicide treatments evaluated for sugarbeets grown at the Klamath Experiment Station,
1997.
Treatment
No. products
1
Control - untreated
Treatment
Product
application rates
cost '
quantity (a.i.)/A
$/A
0
NA
2 Pyramin DF
+Betamix Progress + UpBeet
+Betamix Progress + UpBeet
1.55 lb (1.05)
1.0 pt (0.17) + 0.5 oz (0.0156)
2.0 pt (0.33) + 0.5 oz (0.0156)
120
4 Nortron EC
+UpBeet + Betamix
+UpBeet + Betamix
2.0 pt (0.38)
0.5 oz (0.0156) + 1.5 pt (0.25)
0.5 oz (0.0156) + 2.0 pt (0.33)
140
5 Nortron EC
+UpBeet + Betamix
+UpBeet + Betamix
3.0 pt (0.56)
0.5 oz (0.0156) + 1.5 pt (0.25)
0.5 oz (0.0156) + 2.0 pt (0.33)
119
8 Pyramin DF; Eptam 7E
1.55 lb (1.05); 3.5 pt (3.06)
42
9 Betamix; Betamix
1.5 pt (0.25); 2.0 pt (0.33)
47
0.5 oz (0.0156)+3 oz (0.07)+0.25 %
0.5 oz (0.0156)+3 oz (0.07)+0.25%
70
11
UpBeet + Stinger + Surfactant
+UpBeet + Stinger + Surf.
132
12 UpBeet + Stinger + Nortron + Surf.
UpBeet + Stinger + Nortron + Surf.
0.5 oz (0.0156)+3 oz (0.07)+1.3 pt (0.24)+0.25%
0.5 oz (0.0156)+3 oz (0.07)+1.3 pt (0.24)+0.25%
1 3 Betamix Progress
1.0 pt (0.17)
2.0 pt (0.33)
49
1.0 pt (0.17) + 0.5 oz (0.0156)
2.0 pt (0.33) + 0.5 oz (0.0156)
94
+Betamix Progress
15 Betamix Progress + UpBeet
+Betamix Progress + UpBeet
16 Hand weed (estimated)
150
1/
Cost of products only.
NA: Not applicable.
Klamath Experiment Station 1997 85
Klamath Experiment Station
Table 2. Effect of herbicide treatments on beet yield, sugar content, sugar yield, and gross crop
value of Bighorn sugarbeets, Klamath Falls, OR, 1997.
Treatment
number
Beet
yield
Sugar
content
ton/A
1
2
4
5
8
9
11
12
13
15
16
Mean
CV (%)
LSD (P = 0.05)
Sugar
yield
Gross crop
value
ton/A
$/A
17.9
32.6
32.8
26.2
33.1
26.8
38.7
36.6
30.8
23.8
41.3
17.6
17.6
18.1
17.2
17.4
17.3
17.3
17.3
17.1
17.2
16.4
3.6
5.7
5.9
4.5
5.8
4.6
6.7
6.3
5.3
4.1
6.8
750
1360
1400
1070
1360
1100
1580
1500
1250
970
1600
31
15
6.8
17.3
5
NS
5.3
17
1.3
1270
17
310
Table 3. Multiyear summary of effects of herbicide treatments on performance of sugarbeets at
Klamath Falls, OR. 1993-97.
Treatment
1/
Percent of trial means
Number of
number
years'
1
2
4
5
8
9
11
12
13
15
16
5
2
2
1
2
5
3
3
5
1
1
beet yield
63
101
108
85
109
101
113
115
109
77
133
sugar content
99
99
103
99
100
101
100
100
100
99
95
Number of years a treatment was included in KES trials.
86 Klamath Experiment Station 1997
sugar yield
63
102
111
85
109
101
114
115
109
76
126
gross value
63
102
111
84
109
101
113
115
109
76
126