Abstract
Forty-four alternative treatments to basal applications of 2,4,5-T were applied to woody vegetation on a utility right-of-way in Broome County, New York. Alternative treatments included modification in herbicide formulations and application techniques, as well as non-chemical methods. Treatment evaluation occurred after two growing seasons for plots established in the spring of 1979 and after one growing season for plots established in fall 1979 and spring 1980.
A primary objective of system reliability establishes the need for vegetation control on electric utility rights-of-way. Through selective management of right-of-way vegetation, progress can be made toward the establishment of a relatively stable vegetative complex composed of those species compatible with the electrical facility above (1).
Prior to the suspension of 2,4,5-trichlorophen-oxyacetic acid (2,4,5-T) by the U.S. Environmental Protection Agency in February 1979, basal application of this herbicide as an ester in fuel oil was a valuable technique in selective vegetation management. The objective of this study has been to test under field conditions available (or soon to be available) alternatives to selective basal applications of 2,4,5-T on woody species typically found on utility rights-of-way in New York State. A second objective has been to evaluate methods of reducing oil requirements through the use of alternatives to straight fuel oil as carriers of the herbicidal active ingredient.
Materials and Methods
One hundred ten plots each being 50 ft. by 50 ft. were established in Broome County, New York on a right-of-way corridor occupied by several electrical transmission lines. There had been no history of previous vegetation maintenance taking place on this site since the clearing for line construction which took place in the late 1960’s.
It was felt that due to the abnormally large size of the vegetation, this site offered “worse case” conditions for a utility right-of-way. Typically stems reached heights of 20 ft. to 25 ft. Stem densities typically ranged from 2,000 to 4,000 stems per acre. Species present in abundance included quaking aspen (Populus tremuloides), red maple (Acer rubrum), red oak (Quercus rubra), white ash (Fraxinus americana), pin cherry (Prunus pennsylvanica) and black cherry (Prunus serotina).
An effort was made to simulate procedures currently in operational practice during chemical application on each 50 ft. by 50 ft. plot. Application was made by closely supervised experienced contract personnel following standard procedures for each treatment. Table 1 defines the methods of applications and Table 2 lists the herbicides which were evaluated in this study.
Methods of application
Herbicides evaluateda
In most cases each formulation and method being evaluated was applied to three separate plots. The volume of chemical applied per plot was dependent upon the vegetative composition and stem density of each plot as they pertain to the specifications of each application technique, and not on a predetermined rate based on unit area. The only exception was in the application of the banding technique.
The field evaluation conducted during August 1980 involved a 100% inventory of a .01 acre sample area centered within each treatment plot. Species, diameter class, and defoliation rating (Table 3) were recorded for each undesirable plant within the .01 acre sample area. The location of foliage or regrowth on those stems not completely defoliated was recorded for each species. Additionally general observations of conditions within the plot were recorded.
Defoliation rating classes
Results & Discussion
Table 4 lists the method of application, herbicide formulation and effectiveness of each treatment investigated during this study.
Study treatments
Recognizing the small sample size of each treatment, the following is a brief discussion of results and observations. A complete reporting of results to date for each treatment has been made in “A preliminary assessment of several potential vegetation management techniques as a substitute for basal applications of 2,4,5-T” (2).
Basal
The evaluated results of applications of several combinations of 2,4-D, dichlorprop and dicamba in oil were variable with no strong relationship readily apparent between treatment and effectiveness (Figure 1). Variation in species composition between plots may be influencing this relationship.
Combinations of 2,4-D, dichlorprop and dlcambe
Basal application of 4 lbs. triclopyr ester and 2 lbs. picloram ester (treatment #13) after two growing seasons had the best overall effectiveness rating. Application of these two materials at lower rates look promising over a broad spectrum of species after one growing season and may show similar results when evaluated after two growing seasons. Triclopyr alone was observed to be somewhat variable on black cherry and oak (Quercus spp.). The ester of picloram alone was variable on oak and was slow to effect red maple. White ash appeared to be somewhat resistant to basal applications of picloram ester. Figure 2 compares the percentage of stems totally defoliated (defoliation rating 100, Table 3) for the six most effective treatments evaluated.
Six most effective treatments.
Modified basal & water basal
None of the formulations was effective enough to be considered of operational value. Significant phytotoxic effects were observed on the understory of nontarget vegetation.
Injection
Results were poor. This may be due to the fact that incisions were widely spaced on stems that were difficult to treat (i.e., large clumps of stump sprouts). There seems to be a relationship between incision spacing and treatment effectiveness.
Stump treatment
In general there was a 75% reduction in stem density determined by a count of sprouting stumps.
Pellets
Picloram (as the potassium salt) in pellet form has proven to be effective after two growing seasons (Figure 2). White ash and red oak were observed to exhibit some degree of resistance.
Mist blower basal
Results show this method to be fairly effective. The extent of oil reduction over conventional basal applications should be tested on larger areas. There was significant damage evident on nontarget vegetation.
Banding & spot treatments
The results after one growing season are inconclusive. There was significant damage evident on nontarget vegetation.
Hack & squirt
Evaluation occurred less than one growing season after treatment application. It is too early to determine anything of significance.
Burn girdling
Stems were heavily foliated after one growing season. Many stems have sprouted below the burn.
Girdling
Stems were heavily foliated after one growing season. Most stems have sprouted below the burn. Most quaking aspen stems have broken off at the girdle.
In conclusion, several alternatives to basal applications of 2,4,5-T have been evaluated. Recognizing the small sample size of each treatment, no single formulation or method can be singled out as the best in all cases. Based on an evaluation of effectiveness after two growing seasons several treatments can be eliminated as ineffective. A more intensive review may now be directed toward the most promising alternatives identified here.
Footnotes
↵1 Presented at the annual conference of the International Society of Arboriculture at Boyne Falls, Michigan in August of 1981.
- © 1981, International Society of Arboriculture. All rights reserved.
In this issue
Jump to section
Related Articles
Cited By...
- No citing articles found.