EPTAM^® FOR YELLOW NUTSEDGE SUPRESSION ON IDLE LAND

 

 

Corey V. Ransom and Joey K. Ishida

Malheur Experiment Station

Oregon State University

Ontario, OR, 2005

 

 

Introduction

 

Yellow nutsedge is extremely competitive with onions and other crops.  Few herbicide treatments are effective for managing yellow nutsedge within an onion crop.  Herbicides that can be used in corn and dry bean can effectively reduce yellow nutsedge tubers in the soil.  Generally, we think that yellow nutsedge does not grow well in a wheat crop because wheat is so competitive.  However, following wheat harvest, yellow nutsedge shoots can be seen actively growing.  Little is known about yellow nutsedge growth following wheat harvest and its potential to produce additional tubers during this time.  Also, the time between wheat harvest and fall ground preparation may be a window to further reduce the yellow nutsedge population.  A special local-needs registration allows Eptam^® to be used to treat “idle land” after crop harvest and prior to planting other crops.  We conducted two trials to determine the utility of Eptam in reducing yellow nutsedge tuber production and to evaluate the effect of Roundup^® on tuber viability.   

 

Materials and Methods

 

Treatments were applied to yellow nutsedge-infested fields following a failed dry bean crop or wheat harvest.  Treatments included Roundup Ultramax II^® at 64.0 fl. oz/acre after harvest and before disking and Eptam at 3.5, 5.0, and 7.0 pt/acre after disking and incorporated with a second disking operation.  The fields were irrigated prior to the first disking.  Roundup was applied at the dry bean and wheat field sites on August 27 and 31, respectively.  Core samples were taken after the initial disking to determine the number of tubers present in each plot.  Eight core samples were taken from each plot and cores measured 4.25 inches in diameter and 8 inches in depth.  The soil was washed from the cores and the number of yellow nutsedge tubers counted.  After the soil surface had dried, Eptam treatments were applied and immediately incorporated into the soil by disking 3 to 4 inches deep.  Eptam treatments were applied to the dry bean site on September 1 and the wheat field site on September 12.  The number of shoots emerging from each plot was determined by counting the number of shoots in 3 1-yd² quadrates.  Because virtually no shoots emerged following the second disking at the dry bean field site, a second set of core samples was not taken.  A second set of core samples was taken at the wheat field site to evaluate the effect of Roundup applications on tuber viability.  A malfunction of a storage chamber caused the extracted tubers to freeze and no evaluation of tuber viability was conducted.   

 

Results and Discussion

 

At the wheat field site, only 3 to 8 shoots/yd² emerged by November 9 and there were no significant differences among treatments.  Treatments were evidently initiated too late in the season.  At this point, disking alone was probably able to prevent additional tubers from being produced.  However, yellow nutsedge growth during the period following wheat harvest and prior to treatment initiation was probably long enough to allow significant tuber production to occur.  This research demonstrated that in order for idle-land treatments with Eptam to be of benefit, they need to be applied as soon after wheat harvest as possible.  Practices such as disking alone may also be effective for reducing yellow nutsedge growth and tuber production.