Research on Jointed Goatgrass In Nebraska

Crop rotations, tillage effects, and cultivar considerations for jointed goatgrass control continue to be the focus of Professor Gail Wicks' research.  Wicks is a Weed Scientist with the University of Nebraska West Central Research & Extension Center in North Platte.  His research focuses primarily on the effects of individual cultural practices in an integrated management program to control jointed goatgrass.  Wicks determined that jointed goatgrass density, number of spikelets or joints, and percent dockage in harvested grain are greater in winter wheat-fallow rotations than in rotations incorporating spring crops.  A wheat-fallow-corn-corn-fallow rotation is out-performing other rotations with respect to jointed goatgrass control.  Wicks advised, "If the jointed goatgrass infestation is heavy, growers should use longer rotations incorporating spring crops with winter wheat and fallow.  It appears that it would be wise to follow the first crop of corn with a second crop of corn.  This would assure that sufficient time has been allowed to reduce viable jointed goatgrass seed density to an amount that would not affect winter wheat yield in a dry year."  

Wicks explained why corn was used in rotation for jointed goatgrass control and not grain sorghum, "Grain sorghum continues to grow in the fall, drying out the soil and preventing jointed goatgrass seed germination.  Lower soil moisture following sorghum may reduce winter wheat yields (and plant competition) following the fallow phase of this rotation."

Unlike research in Kansas, Wicks research in Nebraska shows that tillage helps to control jointed goatgrass.  He states, "Beginning tillage for fallow, wheat, and corn production in April provided conditions suitable for more jointed goatgrass seeds to germinate before wheat planting than no-till in the wheat stubble and minimum tillage in corn stubble.  This trend has been consistent across four years."  Tillage did not reduce corn yields in 1998 and 1999 due to timely rains, but corn yields were less using tillage for corn in 1997 and during the drought year of 2000.  As for post-harvest tillage, Wicks said, "It all depends on the weather and moisture conditions.  If fields receive enough moisture, post-harvest tillage may stimulate more jointed goatgrass seed germination than waiting until the following spring to till."

     Wheat cultivar comparisons for jointed goatgrass management include Pronghorn (relatively tall), Alliance (medium height), and Vista (relatively short).  "Planting a medium-tall cultivar like Pronghorn reduces jointed goatgrass seed production compared to a short cultivar like Vista," said Wicks.  "jointed goatgrass seed production may not be reduced by planting tall wheat cultivars every year.  This is probably related to environmental conditions and fertility management."  Wicks added, "In the fall, jointed goatgrass densities were less in the corn (plots) that was planted into Pronghorn wheat stubble vs. Alliance and Vista stubble.  Corn yield was greater with corn planted into Pronghorn stubble than Vista wheat stubble."  In addition to Pronghorn, Alliance and Arapaho wheat cultivars also compete well with jointed goatgrass in the wheat-fallow-corn-corn rotational system.

To find out more about the research conducted by Gail Wicks please contact him at gwicks1@unl.edu or contact Doug Schmale, JGG Extension Coordinator.

Dr. Drew Lyon, a Weed Scientist at the University of Nebraska's High Plains Ag Lab Weed Tour in Sydney, has worked extensively on managing Clearfield wheat in western Nebraska cropping systems.  Dr. Lyon is currently cooperating with Dr. Steve Miller at the University of Wyoming on a study to evaluate proper management of Clearfield wheat in crop rotations for control of jointed goatgrass in the Central Great Plains.  The basis of this study is that using Clearfield wheat every 2 or 3 years will provide more sustainable jointed goatgrass control and less risk of developing herbicide resistant jointed goatgrass-wheat hybrids compared to a continuous rotation.

To find out more about the research conducted by Dr. Drew Lyon please contact him at dlyon@unlnotes.unl.edu or contact Doug Schmale, JGG Extension Coordinator.