Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

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EVALUATION OF HERBICIDES FOR CONTROL OF AUTUMN OLIVE USING FOLIAR
TREATMENTS. J.M. Johnson, A.E. Gover, and L.J. Kuhns, The Pennsylvania State
Univ., University Park.
ABSTRACT
As part of an ongoing research project funded by the Pennsylvania Department
of Transportation, a study was established to investigate the effectiveness of several
herbicides and tank mixes for controlling autumn olive (Elaeagnus umbellata Thunb.,
ELGUM).
This trial was established in a pasture near University Park, PA. Sixty ELGUM
were tagged and measured to determine crown diameter and height. The treatment
volume for each shrub was derived using the calculated crown profile area (average
diameter by height) and a targeted application volume of 935 l/ha. Target plant height
ranged from 1.7 to 3 m.
The study was arranged in a randomized complete block design with twelve
treatments and five replications, with each plant serving as a replicate. Treatments
were foliar applied on July 7, 2005 using a CO 2 -powered sprayer equipped with a spray
wand and single TeeJet XR8008VS tip. Herbicide treatments, in kg ae/ha, included
metsulfuron at 0.042, alone or in combination with a premix of dicamba at 0.28 plus
diflufenzopyr at 0.11; metsulfuron at 0.084 plus triclopyr (triethylamine) at 2.5;
metsulfuron at 0.13 combined with either imazapyr at 0.56, fosamine at 12.1, picloram
at 0.56, or fosamine at 12.1 plus imazapyr at 0.56; imazapyr at 1.1; glyphosate
(isopropylamine) at 3.4; triclopyr at 3.4; and fosamine at 4.0 plus imazapyr at 0.07. A
nonionic surfactant 1 was added to all treatments at 0.25 percent v/v, except those
containing the surfactant-loaded glyphosate. Percent canopy reduction was visually
rated on September 1, 2005 and July 10, 2006, 8 and 50 weeks after treatment (WAT).
At 8 WAT, ELGUM treated with triclopyr alone or in combination with metsulfuron
was completely defoliated. ELGUM treated with metsulfuron plus fosamine and
metsulfuron plus picloram was rated at 79 to 93 percent canopy reduction.
When rated 50 WAT, ELGUM treated with metsulfuron at rates (kg ae/ha) of
0.084 or higher, imazapyr alone at 1.1, or triclopyr alone at 3.4 had average canopy
reduction ratings of 91 to 100 percent. Reduction ratings for fosamine plus imazapyr
were significantly lower than the best rated treatments at 70 percent. Treatments
including metsulfuron at 0.042, or glyphosate alone at 3.4 were ineffective at controlling
autumn olive.
1 ChemSurf 90, Chemorse Ltd., Des Moines, IA.
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