Vol. 54—2000 - NorthEastern Weed Science Society

BACKPACK-BASED BRUSH MANAGEMENT ON A LIMITED ACCESS RIGHT-OF-WAY
J.M. Johnson, A.E. Gover and LllII)' J. Kubas"
ABSTRACT
Withina limitedaccess right-of-way, at leastthreevegetationmanagementzones shouldbe
designated. Thesemanagementzones includea non-selectivezone addressingthe shouldersand
guiderails; a safety clear zone extending at least 30 feet from the road edge that is kept free of all
woody vegetation;anda selective zone extendingto 80 feet fromroadedge, wheretall growing
woody species, as well as anyotherundesirablespecieswould besuppressed. Withthis zone
conceptin mindthe PennStateRoadsideResearchProject,a cooperativeprojectbetweenThe
PennsylvaniaStateUniversityandThePennsylvaniaDepartmentof Transportation, set out to
establisha largescale demonstrationof selective brushcontroltechniques. Inparticular,to
demonstrate the effectiveness of backpack-based applications on managing vegetation in the
selective zone. A 14 mile stretch of 1-78 in Northampton County was chosen for the
demonstration.This sectionofI-78 was firstopenedto trafficinNovember,1987. The initial
applicationsweremadein October, 1993. At thattime,the most commonbrush species were
staghom sumac(Rhus typhina L.) and black locust (Robinia pseudoacacta L.). Other species
included: boxelder maple (Acer negundo L.), shrub-type willows (Salix spp.), black birch
(Betula lenta L.), yellow-poplar (Liliodendron tulipi[era L.), sycamore (Platanus occidentalis
L.), Ailanthus (Ailanthus altissima Mill.), and Pauiownia (Paulownia tomentosa Thunb.).
Table I lists the vegetation efforts that were undertaken by the research project, as well as
time,materialsandcomments. The PennStatelPennDOTRoadsideVegetationManagement
project hasspent nearly 300 hOUTSaetually treating brush in this corridor, in addition to other
projectsandfollow-up evaluations. Vegetationmanagementin the selective zone is crucialto
maintaininga safecorridor,butis oftenneglected. Thehazardsassociatedwithtall growing
treesfallingontothe roadwayandlimited.sightdistancearetheprimaryconcernsassociated.with
vegetationin thiszone.
Thereareseveralconsiderationsworthmentioningforvegetationmanagementin the
selective zone. Clearingas farfromtheroadwayas practicalduringconstructionis essential.
Areasalong1-78thatarenativeterrain,whereno cutor fill activitywas done,were often cleared
to only 50 feet from the madway. These areas are populated by large trees that were probably
tall enough to fallon the roadway when it was built. Again, a distanceof eighty feet from the
roadway should be managed for the elimination of tall growing trees where the right-of-way
width allows.
A brushmanagementprogramshouldbeinitiatedas soon as possible afterconstructionof a
limited-access roadway. Six years after the opening of l- 78, there was already large, well
established brush present. The sooner a brush management program begins, the smaller the
brush, the more selective the applications can be and the less damage will be done to desirable
vegetation.
The Krenite-based applications relied on in this demonstration werespecific to brush. To
addresstheherbaceousspecies suchas Canadathistle(Cirsium arvense L.) orJapanese
knotweed (Polygonum cuspidatum Sieb. & Zucc.) at the same time as brush, a mix based around
glyphosate or bmadleaf chemistry should be employed. Where colony-forming herbaceous
vegetationis treated,reseedingdesirablespecies is necessary.
For contracting purposes, a contract crew should be able to switch between backpacks and
truckbasedhosesbased on the vegetation. Thesemethodsof applicationprovideflexibility.
greaterselectivityandarerelativelyinexpensive. Basedon roughareaestimatesusingthe most
expensivevisit (7/98), the cost of managing brushin thiscorridorworksoutto about$6.50/acre
peroperation.Thiscost was arrivedat usingthe following estimates:
14 miles long, two 80 ft shoulders, a 50 ft median ~ 356 acres; $24/hOUTX77 hours ~ $1848;
herbicide cost = $436.
11ProjectAssociate,ProjectAssociate.andProfessorofOmamentalHorticulture, respectively,ThePennsylvania
StateUniversity,UniversityPark,PA 16802
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