Vol. 51—1997 - NorthEastern Weed Science Society

72
BVAL
ATION OF BURN-DOWN MATERIAl.S FOR TOTAL VEGETATION CONTROL
UNDER GUIDE RAILS
Jon M. Johnson, Chad W. Spackman and Larry J. Kuhnsl/
ABSTRAcr
A stud evaluating glufosinate-ammonium (glufosinate) and pelargonic acid (Scythe2') for
total vege lion control along roadsides was initiated as part of a cooperative project between The
Pennsylv ia State University and The Pennsylvania Department of Transportation. Roadside
treatments were applied to 3 by 25 ft plots located along a guiderail near State College, PA, on July
20, 1996; sing a CO2-powered hand held sprayer. To compare any potential differences in spray
volumes, GPA and 80 GPA were both applied using either two Spraying Systems OC-04 spray
tips at 23 si or two OC-08 spray tips at 36 psi, respectively. Visual ground cover ratings of
annual an perennial weed species were taken July 18, to assess the original weed pressure and
July 29, 9 ys after treatment (DAT); August 30, 41 DAT; and October 4, 1996, 76 DAT.
Predomin t weed species were common lambsquarters (ChenopodiumalbumL.), common
ragweed ( rosiaartemisiifoliaL.), wild carrot (DaucuscarotaL.), wild parsnip tPastinaca
sativaL.), spotted knapweed (CentaureamaculosaLam.), chicory (CichoriumintybusL.), white
sweetelov r (Melilotusalba Medik.), giant foxtail (SetariafaberiHerrm.), and green foxtail
(SetariaVI idis L.).
The in tial green cover ratings were, on average, between 78 and 94 percent for all plots.
Glufosina was the only postemergent product that provided significant early signs of necrosis to
the trea plants 9 DAT. By 41 DAT, treatments containing sulfometuron methyl and diuron
combined ith a postemergent product and imazapyr plus diuron provided significantly better
control th all other treatments, with green cover 15 percent or less. Glufosinate alone;
glufosina plus 2,4-D; glufosinate plus imazapyr; Scythe plus glyphosate; and sulfometuron
methyl pI diuron all provided poor control.
All tre tments began to show an increase in weed pressure 76 DAT. The glufosinate,
glufosina plus 2,4-D, and glyphosate all continued to show excellent long-term control when
used in co bination with sulfometuron methyl and diuron. The imazapyr and diuron mix also
maintain excellent control at this rating period
Glufo . ate, when tank mixed with sulfometuron methyl and diuron, provided statistically
similarres Its at both the 0.5 and 1lbla rates. Glyphosate at 21b/a performed well at both 41 DAT
and 76 D T when tank mixed with sulfometuron methyl and diuron, Reducing the rate of
glyphosa to Ilbla and adding Scythe did not significantly reduce control. Treatments 10 and 12
compared Scythe, glyphosate, sulfometuron methyl, and diuron at 40 versus 80 GPA. There was
no statisti al difference noted at any rating period between these two treatments.
rapid bumdown and long-term control control are desired, glufosinate at both 0.5 and 1
ufosinate plus 2,4-D , when combined with sulfometuron methyl and diuron can be
11Project istant, ResearchTechnologist,andProfessorof OrnamentalHorticulture,respectively,The
Pennsy ania State University,UniversityPark,PA. 16802
2/Scythe,5 % pelargonicacid, MycogenCorp.