1. List of Treatments in 2015 Injection Study
Use of Aminocyclopyrachlor to Control Midstory and Understory Stems in a Hardwood Stand Austin Gentry1, Andrew W. Ezell2, Andrew B. Self3, and Heidi Renninger3 Mississippi State University, Department of Forestry, 1Graduate Research Assistant, 2Major Professor, 3Committee Members
Abstract
Method® herbicide was evaluated for use as an injection material in hardwoods. In addition to control efficacy, non-target impact on red oak species was evaluated. All treatments containing Method® provided very good control and this herbicide shows promise for use in hardwood management.
Plot Information
The project was installed using a randomized complete block design with plot dimensions of 10’ x 100’. Three replications of all treatments were applied.
Application Information
All treatments were applied on October 7, 2015 with hatchets and 1-quart spray bottles. All trees between 0.5” and 6.0” dbh ,except red oak species, were injected using an application rate of 1 hack per 2” dbh with 1mL of solution per hack. No red oak stems greater than 3.0” dbh were injected for two reasons: (1) to evaluate the efficacy of treatments on those species in smaller stems, and (2) to evaluate any non-target impact on larger non-injected red oak stems.
Evaluation
Injected stems were recorded by species and in 1” diameter classes at the time of treatment application. Living trees were recorded by species/diameter at 1 year after treatment (1YAT) and 2 years after treatment (2YAT). Control was based on the percent reduction in cumulative diameters* per species and overall total reduction (all species) in cumulative diameters.
*Cumulative diameters = # of stems x diameter class (ex. 10 stems in the 2” class would be 10x2=20)
Results
Major results include (Table 1):
No non-target impact was observed on any red oak stems
A rate response for Method® herbicide application was observed in the three principal species
Red maple was the most difficult to control of the primary species
Three-way mixes used in the study provided excellent control
Table 1. Results of injection study 2 years after treatment
List of Treatments in 2015 Injection Study
Treatment #
Herbicide and Mix Rate 1
Untreated 2
Method (6.6% v/v) 3
Method (10% v/v) 4
Method (6.6% v/v) + Arsenal Powerline (6.6% v/v) + Escort (4g/gal) 5
Method (5.3% v/v) + Arsenal Powerline (6.6% v/v) + Escort (7g/gal) + Rodeo (46.6% v/v) 6
Arsenal Powerline (13.3% v/v) + Rodeo (40% v/v) + Milestone (6.6% v/v) 7
Arsenal Powerline (9% v/v) + Accord XRTII (38.5% v/v)
Introduction
Injection has been proven to be an essential component in natural regeneration efforts for oaks. While the majority of herbicide applications in forestry are through broadcast application, such as site preparation, injection has been used in forestry applications for decades and is still a very useful tool. This study evaluates the use of Method® herbicide in injection applications.
Objective
Evaluate the efficacy of Method® herbicide (active ingredient = aminocyclopyrachlor) for injection in hardwood stands used alone or in mixtures
Percent Reduction of Cumulative Diameters by Species in 2015 Injection Study - 2YAT
Species*
Treatment #
AME
REO
REM
Total 1
66.7c**
+21.4b^
+6.5e
+23.1c 2
87.1ab
90.0a
83.3b
91.0a 3
92.4a
97.7a
96.9a
93.0a 4
100.0a
94.5a
93.3a
95.1a 5
98.7a
98.3a 6
96.3a
96.2a 7
95.9a
97.4a
48.0cd
82.1b
*AME= American elm, REO = red oaks, REM = red maple
^ plus sign indicates an increase in cumulative diameters
** values in a column followed by the same letter do not differ at alpha = 0.05
Conclusions
Method® shows promise for use in injection work for hardwood management. There was an evident rate response in Method® alone treatments for the principal species, but overall, the low rate performed almost as well as the higher rate. Method® alone performed almost as well as the mixtures in controlling the species in this study. Control of most species improved in the second year. Five of the six treatments resulted in >90% control, but treatment #7 was impacted by red maple resprout during year two.
Methods and Materials
Study Site
Research was conducted a hardwood stand located in the Noxubee River floodplain of MSU’s John Starr Forest, 14 miles south of Starkville, MS (Figure 1). Principal species were American elm, willow oak, water oak, diamondleaf oak, cherrybark oak, and red maple. Other species present included yellow poplar, winged elm, sweetgum, and American hornbeam.
Acknowledgements
Bayer Crop Science
MSU John Starr School Forest Personnel
Figure 1. Study Site on MSU John Starr Forest