Vol. 54—2000 - NorthEastern Weed Science Society

EFFECT OF RATE, FORMULATION AND APPLICATION METHOD ON
EFFICACY AND PHYTOTOXICITY OF GRANULAR HEXAZINONE
IN WILD BLUEBERRY FIELDS
D. E. Yarborough and T. M. Hess'
ABSTRACT
Granular hexazinone has been used in wild blueberry fields since 1993, either as a liquid
impregnatedon fertilizeroras a 10%granule. Concernsaboutlackof efficacyand
blueberryinjurywhenappliedwitha Vicoo-typespreaderprompteda requestto evaluate
a 5%granuleto providefor betterdistributionandcrop safety. Granularhexazinonewas
appliedas PrononeMG® on 6/16/99 witheitheranairassistspreaderorVicon®
spreaderat 1 or2 Ibai/ain a 50/0or 10%formulationto 1.5acreblockson a commercial
blueberry field on Township 18 MD, Maine. Ten, I meter square transect per treatment
block were evaluated for two untreated blocks and for each application equipment,
formulation and rate (2x2x2~ 8 treatment blocks) on 8/6/99 for weed cover and
phytotoxicity to blueberry plants. The effect of equipment was highly significant with
the air-assist application having a greater weed cover and less phytotoxicity and the
Vicon spreader with less weed cover and a higher phytoxicity rating. With both the airassistspreaderandtheViconspreader,weedcoverwas
reducedforthetreatedvs the
untreated and was lower for the 2 lb vs the I Ib rate but formulation percentage had no
effect on weed.cover. Phytotoxicitywas significantlyhigheron the 10%vs the 5%
formulation, whenappliedwiththeVicon spreader,butrateor formulationhadno
significanteffect on phytotoxicitywhenappliedwithan airassist spreader. So the 5%
granule would provide better crop safety when used at the higher rate in the Vicon
spreaderbuthadno significanteffect on weedcover. No effect on weedcover or
phytotoxicityforthe5%vs 100/0formulationwas seen whenappliedwiththeair-assist
spreader.
, Blueberry Specialist and Research Associate, University of Maine, Orono, ME 04469­
5722
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