Postemergence Control of Feral Rye in Clearfield Wheat with ALS Inhibiting Herbicides.
Billie McKean and Case Medlin. Oklahoma State Univ, 2307 N Lakeview Court, Stillwater, OK 74075
Feral rye (Secale cereale L.) is a major weed problem in many Oklahoma wheat
fields. Feral rye infestations decrease
the economic potential by lowering the amount of harvestable crop through
direct competition and also dockage losses through contamination of the
harvested grain. Due to its robust growth habit and similar growing season,
it's a difficult weed in Oklahoma wheatfields to control. The only labeled in-season chemical control
practice for this weed is imazamox herbicide which requires the planting of
imidazolinone-tolerant wheat. Imazamox
marginally controls feral rye. Methods
for improving control of feral rye are needed and should be researched. The objective of this research was to
evaluate feral rye control with various herbicide options in Clearfield winter
wheat. In 2006, a field study was
conducted at OSU's North Central Research Station near Lahoma, Oklahoma. The experimental design was a randomized complete
block with four replications.
Treatments included imazamox (35 and 55 g ai/ha), imazapyr (70 and 195 g
ai/ha), or nicosulfuron (55 or 70 g ai/ha) applied with two different
surfactants (i.e. Dyn-A-Pak and Induce).
Treatments were applied postemergence in March 2006 with a CO2 backpack
sprayer and a hand held boom. Weed
control and crop injury ratings were recorded from two weeks after application
until harvest. There were no notable differences in weed control or crop
response due to herbicide application rate or surfactant used. At 4 weeks after
application (WAA), imazamox and imazapyr controlled feral rye at least 98%,
regardless of rate or surfactant used.
Imazamox applications resulted in the lowest crop response ratings (less
than 5%) of the products evaluated.
Crop injury from imazapyr ranged from 11% to 21%. Nicosulfuron controlled feral rye less than
85% and resulted in at least 80% stunting of the crop.