2
4
6
8
Oustar Herbicide for Efficient Herbaceous Weed Control and Enhanced Loblolly
Pine Seedling Performance in the southeastern United States
Jimmie L. Yeiser, Professor and T.L.L. Temple Chair, Stephen F. Austin State
University, Arthur Temple College of Forestry, P.O. Box 6109 SFA,
Nacogdoches, TX 75962. 936-468-3301(w); 936-468-2489(f); [email protected]
Andrew W. Ezell, Professor, Mississippi State University, Department of
Forestry P.O. Box 9681, Mississippi State, MS 39762-9681.
1
Abstract
2
4
6
8
10
12
14
16
18
20
22
24
26
28
Oustar herbicide is a new pre-mixed blend of hexazinone (Velpar
DF)+sulfometuron (Oust XP). Tests at six sites in the southeastern United
States were established to compare Oustar (0, 10, 13, 16, 19 oz product ac-1)
to industry standards (Velpar L+Oust 32+2; Arsenal AC+Oust 4+2, both in oz
product ac-1) for herbaceous weed control (HWC) and resultant loblolly pine
(Pinus taeda L.) seedling performance. Sites were prepared prior to planting
with: fire only, chemical followed by a burn, mechanical only, or chemical
and mechanical methods. Oustar (13 oz) and industry standards provided
similar HWC and seedling performance. When averaged across all six sites,
herbicide plots consistently had more bareground than untreated plots by
nearly 2X at 30 days after treatment (DAT), 3X at 60-DAT, 4X at 90-DAT, and
5X at 120-DAT. Similarly, herbicide treatments increased age-two seedling
survival (9%), total height (0.69 ft), ground line diameter (0.26 in), and
volume index (1.54x10-2 ft3) over that of untreated seedlings. Late (October)
site preparation commonly resulted in less herbaceous cover on application
day. Sites with less ground cover on application day exhibited more
bareground at 60- and 120-DAT than sites with high initial ground cover. The
low rate (10 oz) of Oustar applied to sandy loam soils receiving chemical and
mechanical preparation prior to planting provided bareground comparable to
industry standards. Managers integrating late site preparation followed by
spring HWC may achieve customary levels of HWC for more of the growing season
with less herbicide than industry standards. Site preparation by HWC
interactions reported for loblolly pine may have broader applications to
coniferous plantation establishment. More research is needed to define
additional site preparation by HWC interactions and their usefulness in
coniferous plantation establishment. No adverse herbicide effects were seen
on any crop trees.
30
32
Author Keywords: Herbaceous control, herbaceous weed control, vegetation
management, pine management, Oustar, Oust, Velpar, Arsenal, Pinus taeda,
loblolly pine
34
2
Introduction
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
Historically, forest managers in the southeastern United States have been
concerned about the negative impact of herbaceous competition on loblolly
pine seedling performance. Since the 1970s, numerous studies have addressed
relationships between herbaceous weeds and loblolly pine seedling survival
and growth (Holt et al., 1975 and Creighton et al., 1987). Herbaceous weeds
are known to compete with newly planted loblolly pine seedlings for water,
nutrients, light, and space (Nelson et al., 1981, Tiarks and Haywood, 1986
and Zutter et al., 1986). When compared to plantings without herbaceous weed
control (HWC), treated loblolly pine plantations are commonly characterized
by increased planting survival that persists into midrotation (Clason, 1987),
enhanced growth (Glover et al., 1989), early commercial thinning (Glover et
al., 1989), and shorter rotations (Clason, 1989 and Glover et al., 1989).
Therefore, HWC is a commonly accepted practice in loblolly pine plantation
management in the southeastern United States.
Velpar L (hexazinone) and Oust (sulfometuron) are forest herbicides
manufactured by E.I. du Pont de Nemours and Company. These products were
packaged, sold, stored, and handled separately in early research (Fitzgerald,
1976 and Creighton et al., 1987) and operational trials for pine release.
Managers now realize Velpar L and Oust mixtures offer economical (Dangerfield
and Merck, 1990 and Miller et al., 1994), broad-spectrum control (Zutter et
al., 1987) with excellent pine tolerance for enhanced seedling performance.
Consequently, a tank mixture of Velpar L and Oust is an industry standard for
HWC (Muir and Zutter, 1998 and Muir and Zutter, 1999).
Each gallon of Velpar L contains 25% hexazinone, plus alcohol and other
ingredients for stability and shelf life. Because of the alcohol, Velpar L is
more flammable than other forest herbicides.
Oust herbicide was a granule containing 75% sulfometuron. The product was pan
granulated with chemical binders that hold the dust-like particles together.
When added to water, Oust formed a suspension and if allowed to sit, Oust
settled to the tank bottom. There, the same binders used to hold the dry
particles together turn the Oust-particles into a paste. Good agitation prior
to spraying was required for re-suspension.
38
40
42
44
New extruded granular formulations of Oust and Velpar were tested in 1999
(Wood and Yeiser, 2000). Extruded granules lack the chemical binders
previously used for pan granules. Consequently, the new formulation of Oust,
Oust XP, has improved solubility. If allowed to settle, Oust XP requires less
agitation than the original Oust for re-suspension. Compared to Velpar L, the
new formulation, Velpar DF (dry flowable), is alcohol free and 75%
concentrated.
46
48
50
52
54
56
58
Oustar, developed for testing in 2000, is a pre-mixed blend of Oust XP (11.5%
sulfometuron) and Velpar DF (63.2% hexazinone). It brings the enhanced
properties of the new formulations into one container for increased
convenience of storage, handling, and mixing. Furthermore, the new granules
of Oust XP and Velpar DF are identical in size, shape, and density to prevent
segregation during handling and transportation. Oustar (13 oz) contains the
same amount of active ingredients as the standard tank mix of Velpar L+Oust
(32+2 oz) and is of particular interest to managers.
The objective of this project was to compare use rates of Oustar to
conventional industry standards (Velpar L+Oust 32+2; Arsenal AC+Oust 4+2,
both in oz product ac-1) for HWC and enhanced survival and growth of loblolly
pine seedlings.
60
Materials and methods
3
2
Study sites
4
Field trials were established in March 2000 at six sites: in Cold Point, SC;
Diboll and Lufkin, TX; Picayune, MS; Starkville, MS; and Whitfield, AL
(Figure 1). The sites were selected to vary in preparation intensity and
timing (Table 1). A wildfire at Lufkin is an example of low intensity
preparation. Chemical and mechanical treatments at Diboll and Cold Point
exemplify high intensity preparation. Shear, rake, and windrow at Whitfield
in July is considered early preparation and the same methods in October at
Picayune is considered late preparation. Cold Point, Picayune, and Starkville
were hand planted in January and Lufkin in February with bare root seedlings.
Whitfield was machine planted with bare root seedlings while Diboll was hand
planted with containerized seedlings both in January. All sites were planted
in 2000.
6
8
10
12
14
16
Study treatments
18
26
Herbicide treatments were applied pre-emergence at Cold Point, Diboll,
Picayune, and Starkville , and post-emergence at Lufkin and Whitfield (Table
1). Herbicide treatments were: (1) Oustar 10 oz, (2) Oustar 13 oz, (3)
Oustar 16 oz, (4) Oustar 19 oz, (5) Velpar L+Oust 32+2 oz, (6) Arsenal
AC+Oust 4+2 oz, and (7) untreated check. All rates are presented in ounces of
product per treated acre. Herbicides were applied in 5-ft bands centered over
the top of seedling rows. Total volume of herbicide mix was 10 gallons per
acre.
28
Study plots
30
Treatment plots in Diboll, Lufkin, and Starkville contained 16 seedlings in a
single row. Measurement plots, inside treatment plots, contained 12 seedlings
with 2 buffer seedlings on each end. In Cold Point, Picayune, and Whitfield,
treatment and measurement plots contained 10 seedlings.
20
22
24
32
34
40
Treatments were visually evaluated for percent bareground prior to herbicide
application and at 30, 60, 90, and 120 DAT (Miller and Glover, 1991).
Seedlings were assessed for survival (%) and measured for height (HT, ft) and
ground line diameter (GLD, in) prior to treatment and after one and two
growing seasons. Volume index (VI) was computed as VI=HT X GLD2 and expressed
in ft3. Year-one ground cover and year-two seedling growth are presented.
42
Data analysis
44
48
Each test site had four blocks. Treatments were assigned in a randomized
complete block design. Treatment effects were partitioned by an analysis of
variance with means separated using Duncan’s New Multiple Range Test
(α=0.05). All percent data were arcsine-square root transformed prior to
analysis.
50
Results and discussion
52
Overall mean bareground
Overall bareground (weed free) treatment means were computed across all six
sites and presented for each evaluation date (Table 2). At 30-DAT, all
herbicide test treatments were similarly weed free. At 60-DAT, bareground on
plots receiving 10 oz of Oustar was less than for higher Oustar rates, but
similar to industry standards. At 90-DAT, all herbicide treatments provided
very similar HWC with statistical differences detected among the highest
(84%) and lowest (76%) levels of bareground. At 120-DAT, bareground was
similar for all herbicide treatments.
36
38
46
54
56
58
60
4
2
4
6
8
10
12
14
16
18
20
As the growing season progressed, the overall bareground means for 30through 120-DAT varied little between Oustar use rates (Table 2). For
example, bareground at 30-DAT ranged only 5% from a low of 91 to a high of
96%. At 60-DAT, bareground ranged 8% from a low of 84 to a high of 92%. At
90-DAT, bareground ranged 8%, from a low of 76 to a high of 84%. At 120-DAT,
bareground ranged 8% from a low of 61 to a high of 69%. For all evaluation
dates, industry standards consistently provided weed-free growing space
intermediate between the low and high Oustar test rates. Therefore, several
Oustar rates provided HWC comparable to industry standards, allowing managers
to increase or decrease rates as management intensity and budgets dictate.
For all rates and sites, no adverse herbicide effects were seen on any crop
trees.
Herbicide treated plots were consistently more weed free than untreated
checks. In fact, the mean bareground of all herbaceous weed treatments
compared with the untreated check at 30-, 60-, 90-, and 120-DAT was 93 and
46; 89 and 32; 80 and 22; and 66 and 12%, respectively. This is nearly 2X at
30-DAT, 3X at 60-DAT, 4X at 90-DAT, and 5X at 120-DAT more bareground on
treated than untreated plots. The patterns in HWC reported here for Oustar
(13 oz) are similar to those for Velpar L+Oust (32+2 oz) here and reported by
other users (Muir and Zutter, 1999 and Earl and Williams, 2001).
22
Bareground by site
24
26
28
Mean percent bareground varied by site (Table 2). Weed-free conditions were
highest at Picayune (89%) and Diboll (86%). Bareground at Lufkin (71%) was
intermediate and similar to that at Cold Point (69%) and Starkville (68%).
Bareground was lowest at Whitfield (64%) but similar to that at Cold Point
and Starkville. For all evaluations, sites averaged at least 64% bareground.
30
Bareground by DAT by site
32
34
36
38
40
42
The DAT by site bareground means show herbicides promptly provided weed-free
space for seedlings (Table 2). For example, at 60-DAT, percent bareground was
statistically Picayune>Diboll>Cold Point=Starkville=Whitfield=Lufkin and
numerically 93%, 87%, 78%, 76%, 76%, and 75%, respectively. At 120 days,
bareground was statistically Diboll=Picayune>Lufkin=Starkville=Cold
Point>Whitfield and numerically 81%, 77%, 55%, 51%, 49%, and 32%,
respectively. Picayune and Diboll sites on application day had the lowest
ground cover at less than 1% (Table 1). Whitfield on application day had the
highest ground cover at almost 80%. Sites with less ground cover on
application day generally exhibited more bareground at 60- and 120-DAT than
sites with more initial ground cover.
44
46
48
50
52
54
The DAT by site means illustrate the duration of HWC (Table 2). For example,
at Cold Point, bareground peaked 30-DAT (85%) and troughed 120-DAT at 49%, a
decline in HWC of 36%. During this same period, Diboll was 88 and 81% (7%
decline), Lufkin 86 and 55% (31% decline), Picayune was 97 and 77% (20%
decline), Starkville 84 and 51% (33% decline), and Whitfield 81 and 32% (49%
decline). Weed establishment early in the growing season was inhibited by HWC
treatments, allowing seedlings to utilize conditions favorable for pine
seedling growth. As herbicides degraded, weeds commonly recolonized plots
during summer months when conditions were less than optimal for pine seedling
growth. Speed of weed recolonization varied at each site by the herbicide use
rate and the specific tolerance of the invading herb.
56
58
60
The DAT by site by herbicide means provide four points for consideration
(Table 2). First, high rates of Oustar (16 oz, 19 oz) commonly provided best
and similar broad-spectrum HWC across all evaluations and sites. An exception
was at Starkville were bareground for Oustar (19 oz) at 120-DAT was
statistically similar to several test treatments and statistically less by
5
2
4
6
8
16% than Arsenal AC+Oust (4+2 oz). Normally, high rates provide more
bareground with longer persistence than lower rates. The low value for Oustar
(19 oz) at Starkville can be explained. Certain Oustar (13 oz, 19 oz)
treatments were coincidentally colonized by blue vervain (Verbena
brasiliensis Vell.) more than plots treated with other rates. Blue vervain is
tolerant of sulfometuron and hexazinone, the active ingredients in Oustar
(DuPont 2002, 2003). Another example was at Whitfield where Oustar 19 oz
provided less HWC than 13 oz. This too resulted from the presence of Oustar
tolerant, Rubus.
10
12
14
16
18
20
22
24
26
28
30
32
34
Second, HWC among average use rates of all Oustar treatments, Oustar 13 oz,
and the average of industry standards was similar at Cold Point, Diboll, and
Picayune. For example, at Cold Point the average of all Oustar treatments,
Oustar (13 oz), and the average of industry standards was 90, 89, and 84%
bareground, respectively, at 30-DAT; 84, 87, and 82% bareground,
respectively, at 60-DAT; 70, 67, and 63% bareground, respectively, at 90-DAT;
and 56, 48, and 48% bareground, respectively, at 120-DAT. These data
illustrate the highly similar HWC achieved with all Oustar treatments as well
as Oustar (13 oz) and industry standards. In contrast, unexpected patterns in
herbicide performance at Lufkin, Starkville, and Whitfield may be explained
by site preparation method and timing, and species composition of weed
recolonization. For example, in Lufkin where the site was prepared by a
wildfire, only high rates of Oustar (16 oz, 19 oz) sustained best HWC through
120-DAT. Low rates of Oustar and industry standards performed well early but
gradually succumbed to weed pressure. Lufkin was the only test site where one
of two industry standards was not among the best treatments tested. This
illustrates that when site preparation is meager (wildfire) or fails, higher
than customary HWC rates may be required to control established vegetation.
At Starkville, plots treated with Oustar (13 oz, 19 oz) were coincidentally
colonized by herbicide-tolerant blue vervain more than plots treated with
other herbicides. At Whitfield, mechanical preparation in July left ample
time for autumn weed seed dissemination on plots. This was evident on
application day the following April, when weeds nearly 1-ft tall occupied
approximately 80% of the site. Heavy weed levels present on application day
were followed by the most aggressive weed recolonization of plots 120-DAT.
36
46
Third, plots treated with Oustar (10 oz) and industry standards were
similarly weed free at Cold Point, Diboll and Starkville. At Cold Point and
Diboll, low and high rates of Oustar as well as both industry standards
provided prompt and sustained control of competition. At Starkville, blue
vervain in some Oustar (13 oz and 19 oz) plots contributed to the decline of
HWC otherwise comparable to industry standards. Factors likely contributing
to the excellent HWC at Cold Point, Diboll, Starkville, and Picayune are
early April applications to predominately bareground and low levels of
emerging weeds (Table 1). Factors likely influencing competitor levels
include the interaction of timing and methods of site preparation.
48
Seedling performance
50
Mean overall seedling performance
Seedling performance after two growing seasons was averaged across all six
sites (Table 3). As computed from mean values in Table 3, herbicide released
seedlings averaged 86.0% survival, 5.2 ft HT, 1.43 in. GLD, and 5.70x10-2 ft3
VI. These seedling values are similar to that reported previously (Miller et
al., 1986). On average, HWC increased survival (7.2%), HT (0.47 ft), GLD
(0.22 in), and VI (1.22x10-2 ft3) as compared to untreated checks. In a threeway comparison of seedling means for all rates of Oustar, industry standards,
or nothing (untreated checks), survival was 85.4, 87.1, and 78.7%; HT 5.1,
5.4, and 4.7 ft; GLD 1.41, 1.48, 1.21 in; and VI 5.48x10-2, 6.16x10-2, and
4.48x10-2 ft3, respectively. Thus, seedling performance was similar for Oustar
38
40
42
44
52
54
56
58
60
6
2
4
6
8
10
12
14
treatments and industry standards and both significantly better than
untreated checks.
Seedling performance by site
Seedling performance varied by site (Table 3). For example, survival was
statistically Picayune=Whitfield=Diboll>Starkville>Cold Point>Lufkin and
numerically 98.8%, 98.2%, 96.7%, 85.1%, 72.8%, and 65.5%, respectively. Total
height, statistically, was Whitfield>Picayune>Starkville>Diboll>Lufkin>Cold
Point and numerically 6.8 ft, 6.4 ft, 5.5 ft, 4.9 ft, 4.2 ft, and 2.3 ft,
respectively. Ground line diameter, statistically, was
Picayune>Whitfield=Diboll>Lufkin>Starkville>Cold Point and numerically 1.76
in, 1.65 in, 1.58 in, 1.35 in, 1.26 in, and 0.51 in, respectively. Volume
index, statistically, was Whitfield=Picayune>Diboll=Starkville>Lufkin>Cold
Point and numerically, 8.12x10-2 ft3, 8.0x10-2 ft3, 5.79x10-2 ft3, 5.26x10-2 ft3,
4.19x10-2 ft3 and 0.93x10-2 ft3, respectively.
16
18
20
22
Herbicide treatments commonly increased seedling survival and growth over
untreated checks. In a comparison of treated versus untreated, performance
was significantly enhanced for: survival at three of six sites-Cold Point,
Lufkin, and Picayune; HT at three of six sites-Lufkin, Starkville, Whitfield,
and overall; GLD at five of six sites-Diboll, Lufkin, Picayune, Starkville,
Whitfield, and overall; and VI at five of six sites-Diboll, Lufkin, Picayune,
Starkville, Whitfield, and overall.
24
26
28
30
32
34
In a two-way comparison of Oustar (13 oz) and Velpar L+Oust (32+2 oz) across
five sites and three seedling growth parameters, Oustar provided
statistically similar, greater, or less growth 11, 0, and 4 times,
respectively. In a two-way comparison of Oustar (13 oz) and Arsenal AC+Oust
(4+2 oz) across five sites and three seedling growth parameters, Oustar
provided statistically similar, greater, or less growth 12, 0, and 3 times,
respectively. Starkville was not included in these analyses because of the
invasion of blue vervain in the Oustar (13 oz, 19 oz) treatments. Results
show seedling performances for Oustar (13 oz) and industry standards were
very similar. Thus, managers can use Oustar (13 oz) and anticipate seedling
growth comparable to Velpar L+Oust (32+2 oz) or Arsenal AC+Oust (4+2 oz).
36
42
Growth means (Table 3) did not closely parallel the site preparation by HWC
patterns observed in the DAT by site by herbicide means (Table 2). Climate
probably impacted seedling performance. For example, the Texas sites were
planted in early 2000 during a major fall-winter drought that probably
influenced initial growth. Normal spring rainfall occurred prior to a major
summer-fall drought for all sites during the test year, 2000.
44
Conclusions
46
Several use rates of Oustar, including Oustar 13 oz, and industry standards
provided comparable HWC and loblolly pine seedling performance at six test
sites in the southeastern United States. Results show the potential of Oustar
for safe HWC and enhanced loblolly pine seedling survival and growth for a
variety of site conditions and preparation methods common to southern pine
management. Interactions between timing of site preparation and HWC
treatments were detected. Timing and method of site preparation followed by
HWC with Oustar can be integrated to achieve more efficient and cost
effective total vegetation management. Additional research is needed to
define more site preparation and HWC interactions and illustrate their
usefulness in coniferous plantation establishment.
38
40
48
50
52
54
56
58
7
References
2
4
6
Clason, T.R.,1987. Effects of competing vegetation on loblolly pine plantations. LA
Agric. 31(1),7-9.
Clason, T.R.,1989. Early growth enhancement increases loblolly pine rotation yields.
South. J. Appl. For. 13(2),94-99.
8
10
Creighton, J.L., Zutter, B.R., Glover, G.R., Gjerstad, D.H.,1987. Planted pine growth
and survival responses to herbaceous vegetation control, treatment duration, and
herbicide application technique. South. J. Appl. For. 11(4),223-227.
12
14
16
18
Dangerfield, C.W., Jr., Merck, H.L.,1990. Helping pines earn more with weed control.
USDA Forest Service South. Region Tech. Paper 14, 23p.
DuPont,2002. DuPont Oust XP herbicide. E.I. du Pont de Nemours and Company.
Wilmington, DE. 11p.
DuPont,2003. DuPont Velpar L herbicide. E.I. du Pont de Nemours and Company.
Wilmington, DE. 19p.
20
22
24
Earl, J.A., Williams, R.A.,2001. Comparing rate ranges of Oustar herbicide with
industry standards. Proc. South. Weed Sci. Soc. 54:162-165.
Fitzgerald, C.H.,1976. Post-emergence effects of Velpar in a piedmont pine plantation.
Proc. South. Weed Sci. Soc. Amer. 29:299.
26
28
30
Glover, G.R., Creighton, J.L., Gjerstad, D.H.,1989. Herbaceous weed control increases
loblolly pine growth. J. For. 87(2),47-50.
Holt, H.A., Voeller, J.E., Young, J.F.,1975. Herbaceous vegetation control as a forest
management practice. Proc. South. Weed Sci. Soc. 28:219.
32
34
36
38
40
Miller,J.M., Glover,G.R., eds.,1991. Standard methods for forest herbicide research.
Champaign, IL. Southern Weed Science Society. 68p.
Miller, J.H., Zutter,B., Zedaker, S.M., Cain, M., Edwards, M.B., Xydias, G.K.,
Applegate, A.R., Atkins, R.L., Campbell, S., Daly, E., Hollis, C., Knowe, S.A.,
Paschke, J., 1986. A region-wide study of loblolly pine seedling growth relative to
four competition levels after two growing seasons. In: Phillips, D.R., (Ed.), Proc.
Fourth Bienn. South. Silvi. Res. Conf. USDA For. Serv. Southeast. For. Exp. Stat. Gen.
Tech. Rep. SE-42, pp. 581-591.
42
44
46
Miller, J.H., Busby, R.L., Zutter, B.R., Zedaker, S.M., Edwards, M.B., Newbold, R.A.,
1994. Response of loblolly pine to complete woody and herbaceous control: projected
yields and economic outcomes-the COMPROJECT. In: Edwards, M.B. (Comp.) Proc. Eighth
Bienn. South. Silvi. Res. Conf. USDA For. Serv. South. Res. Stat. Gen. Tech. Rep. SRS1, pp. 81-89.
48
50
Muir, R.L., Jr., Zutter, B.R.,1998. Screening of imazapic, imazethapyr, and imazaquin
for herbaceous weed control in loblolly and slash pine plantations-first year results.
Auburn University Silvicultural Herbicide Cooperative Res. Note No 98-5, 10p.
52
54
56
58
60
62
Muir, R.L., Jr. and Zutter, B.R.,1999. Pre-emergent herbaceous weed control screenings
in loblolly pine (Pinus taeda) plantations in the Coastal Plain and Piedmont: firstyear results. Auburn University Silvicultural Herbicide Cooperative Res. Note No 99-7,
17p.
Nelson, L.R., Pedersen, R.C., Autry, L.L., Dudley, S., Walstad, J.D.,1981. Impacts of
herbaceous weeds in young loblolly pine plantations. South. J. Appl. For. 5(3),153158.
Tiarks, A.E., Haywood, J.D.,1986. Pinus taeda L. response to fertilization, herbaceous
plant control, and woody plant control. For. Ecol. Manage. 14,103-112.
64
66
Wood, R., Yeiser, J.L.,2000. Herbaceous weed control and resultant pine seedling
growth with new Oust, Velpar, and Escort formulations: year two results. Proc. South.
Weed Sci. Soc. 54:109-113.
68
8
2
4
6
Zutter, B.R., Glover, G.R., Gjerstad, D.H.,1986. Effects of herbaceous weed control
using herbicides on a young loblolly pine plantation. For. Sci. 32,882-899.
Zutter, B.R., Glover, G.R., Gjerstad, D.H.,1987. Vegetation response to intensity of
herbaceous weed control in a newly planted loblolly pine plantation. New Forests
4,257-271.
9
2
4
6
8
10
Figure 1. The southeastern United States showing the six test sites comparing
different use rates of Oustar to Velpar L+Oust (32+2 oz) and Arsenal AC+Oust
(4+2 oz).
12
10
11
2
4
Table 1. A summarized description of the six test sites in the southeastern United States.
Site
Cold Point, SC
Diboll,TX
Lufkin, TX
Picayune, MS
Starkville, MS
Established
2000
2000
2000
2000
2000
Physiography
Soil
6
8
Harvested
Site Prep1
10
Site Prep2
12
14
Treated
Percent Cover
16
Major Forbs
18
20
Major Grasses
22
*
Piedmont
sandy loam
pH 5.4
Jul 98
May 99
Chopper+oil
48 oz+5 qt
Dec 99
combination plow
13 Apr 00
90% bare
<10% @ 6”
pre-emergence
Ambrosia spp
Rubus spp
*
hilly UCP
sandy loam
pH 5.4
Sep 98
Sep 99
Arsenal+Garlon 4
16 oz+2 qt
Oct 99
combination plow
14 Apr 00
99% bare
<1% @ 6”
pre-emergence
Eupatorium spp
Erechtites spp
Croton spp
Panicum spp
Dicanthelium spp Andropogon spp
-
hilly UCP
sandy loam
pH 5.0
May 99
Aug 99
wildfire
15 Apr 00
70% bare
<40% @ 6”
post-emergence
Eupatorium spp
Conyza spp
Panicum spp
Dicanthelium spp
Andropogon spp
*
flatwoods LCP
silt loam
pH 4.2
Dec 98
Oct 99
shear, rake, windrow
48 oz+4 qt
Dec 99
burned windrows
5 Apr 00
99% bare
<1% @ 6”
pre-emergence
Eupatorium spp
Rubus spp
Panicum spp
-
hilly UCP
sandy clay loam
pH 4.2
May 99
Aug 99
Chopper+Accord SP
Oct 99
burned
10 Apr 00
90% bare
<10% @ 6”
pre-emergence
Eupatorium spp
Conyza spp
Panicum spp
Dicanthelium spp
Andropogon spp
Whitfield, AL
2000
interior flatwoods LCP
sandy loam
pH 4.2
Dec 98
Jul 99
shear, rake, windrow
6 Apr 00
20% bare
<80% @ 6”
post-emergence
Eupatorium spp
Erechtites spp
Ambrosia spp
Panicum spp
Dicanthelium spp
-
LCP=lower coastal plain; UCP=upper coastal plain.
12
2
Table 2. Mean bareground (%) 30 through 120 days after treatment (DAT) with Oustar and
industry standards (Velpar L+Oust (V+O); Arsenal AC+Oust (A+O)) for herbaceous weed
control at six loblolly pine sites in the southeastern United States.
4
Site
DAT
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
30
60
90
120
Cold Point, SC
30
60
90
120
Diboll, TX
30
60
90
120
Lufkin, TX
30
60
90
120
Picayune, MS
30
60
90
120
Starkville, MS
30
60
90
120
Whitfield, AL
30
60
90
120
*
A+O
DAT by
13
16
19
*
32+2
91a
84b
76b
61a
94a
90a
81ab
65a
95a
92a
84a
65a
96a
90a
80ab
69a
93a
89ab
81ab
67a
91a
88ab
79ab
66a
46b
32c
22c
12b
85a
81a
76a
53a
89a
87a
67a
48ab
91a
83a
65a
55a
94a
85a
73a
66a
82a
77a
64a
48ab
86a
87a
62a
48ab
65b
44b
31b
26b
85bc
78c
62b
49b
93a
94a
90a
92a
99a
97a
96a
92a
99a
98a
96a
72a
100a
99a
99a
99a
99a
97a
97a
97a
99a
99a
99a
96a
28b
28b
28b
18b
88b
87b
86a
81a
93a
78b
68c
53c
99a
85b
75b
60b
99a
93a
83a
71a
100a
94a
84a
74a
99a
85b
75b
64b
99a
84b
74b
60b
13b
6d
2d
2d
86bc
75c
66b
55b
95ab
92a
90a
75b
98a
96a
96a
89ab
97a
96a
95a
95a
99a
96a
97a
94a
98a
98a
98a
92a
99a
97a
95a
84ab
92b
75b
51b
12c
97a
93a
89a
77a
92a
87a
70ab
63ab
90a
86a
57b
48b
91a
87a
68ab
62ab
90a
84a
67ab
52b
91a
89a
75ab
62ab
93a
83a
80a
68a
37b
17b
5c
5c
84bc
76c
60b
51b
88ab
73c
59c
29b
88ab
91ab
89ab
47a
93a
97a
96a
38ab
95a
81bc
60c
29b
91a
91ab
77abc
39ab
73b
79bc
68bc
38ab
41c
18d
14d
9c
81c
76c
66b
32c
10
*
4+2
Check
Site
†
Mean
Site
Mean
††
¤
69bc
86a
71b
89a
68bc
64c
Ounces of product per acre.
Site by DAT means within a column sharing the same letter are not significantly
different (Duncan’s New Multiple Range Test (α=0.05).
††
48
V+O
Overall Mean
†
46
Oustar
Site means within a column sharing the same letter are not significantly different
(Duncan’s New Multiple Range Test (α=0.05).
¤
50
Site by treatment means within a row sharing the same letter are not significantly
different (Duncan’s New Multiple Range Test (α=0.05).
13
2
4
Table 3. Seedling survival (%), total height (ft), ground line diameter (GLD, in), and
volume index (VI, ft3) two growing seasons following treatment at six sites in the
southeastern United States with Oustar or industry standards (Velpar L+Oust (V+O);
Arsenal AC+Oust (A+O).
Site
Oustar
V+O
A+O
Site
6
Parameter
10
13
16
19
8
Overall Means
Survival†
86.8a
84.5ab
85.0ab
85.4ab
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
85.4ab
4+2
*
88.7a
Check
Mean
††
78.7b
5.0bc
4.9cd
5.2ab
5.1bc
GLD†
1.33d
1.39cd
1.51a
1.40bcd 1.47abc 1.49ab
1.21e
VI (x10-2) †
5.11b
5.15b
6.06a
5.59ab
Cold Point, SC
Survival
Total Height
GLD
VI (x10-2)
87.5a
2.8a
.58a
1.24a
75.0a
2.6ab
.58a
1.18a
Diboll, TX
Survival
Total Height
GLD
VI (x10-2)
97.9a
4.7b
1.45c
5.11b
97.9a
97.9a
93.8a
93.8a 100.0a
95.8a
96.7a
4.7b
5.1ab
4.8ab
5.4a
4.8b
5.1ab
4.9d
1.60abc 1.67ab 1.58abc 1.73a
1.53abc 1.48bc 1.58b
5.44b
6.19ab 5.71b
6.90a
5.70b
5.52b
5.79b
Lufkin, TX
Survival
Total Height
GLD
VI (x10-2)
64.6a
75.0a
70.8a
66.7a
4.0a
4.3a
4.4a
4.6a
1.24bc 1.37ab 1.44ab 1.45a
3.58b
4.26ab 4.54ab 4.84a
12
16
*
Total Height†
10
14
32+2
62.5a
83.3a
2.3ab
1.7c
.48a
.31b
.83ab
.37b
5.5a
5.3ab
4.7d
6.20a
6.11a
4.48c
66.7a
2.4ab
.52a
1.0a
70.8a
2.2bc
.52a
.92a
61.1a
2.2b
.55a
1.0a
66.7a
70.8a
43.8b
4.4a
4.3a
3.0b
1.36ab 1.38ab 1.12c
4.46ab 4.53ab 2.42c
72.8c
2.3f
.51e
.93d
65.5d
4.2e
1.35c
4.19c
Picayune, MS
Survival
100.0a 100.0a 100.0a 100.0a 100.0a 100.0a
Total Height
6.2ab
5.6b
6.4a
6.5a
6.9a
6.6a
GLD
1.63c
1.65bc 1.85ab 1.77abc 1.82abc 1.94a
VI (x10-2)
7.24bc 6.56c
8.44ab 8.13abc 9.01a
8.95a
91.7b
98.8a
6.5a
6.4b
1.68bc 1.76a
7.91abc 8.03a
Starkville, MS
Survival
Total Height
GLD
VI (x10-2)
86.7ab 71.1b
5.9abc 5.2d
1.31bc 1.17c
5.71b
4.56b
86.7ab
4.0e
0.79d
2.36c
85.1b
5.5c
1.26d
5.26b
Whitfield, AL
Survival
Total Height
GLD
VI (x10-2)
95.8a
95.8a
95.8a 100.0a 100.0a 100.0a 100.0a
6.5ab
6.7ab
7.2a
7.3a
6.9ab
6.6ab
6.1b
1.61a
1.63a
1.83a
1.74a
1.72a
1.68a
1.33b
7.44bc 8.10ab 9.61a
8.85ab 8.61ab 8.15ab 6.14c
98.2a
6.8a
1.65b
8.12a
*
84.4ab 82.2b
91.1a
93.3a
5.5bcd 5.3cd
6.1ab
6.3a
1.38ab 1.28cb 1.31bc 1.56a
5.65b
5.15b
5.82b
7.19a
Ounces of product per acre.
†
52
54
Treatment means within a row sharing the same letter are not significantly
different (Duncan’s New Multiple Range Test (α=0.05).
†† Site means for each seedling parameter within a column sharing the same letter are
not significantly different (Duncan’s New Multiple Range Test (α=0.05).
14
Download

herbaceous weed control on newly planted pine stands with oustar