Chute N The Bull 10-18-10

All sports fans know that when the team didn't do as well as expected
this year, there's always next year. Weed control can work like that
too. If you didn't get the sandburs this year, make plans now to get 'em
next year.

We conducted a study in 2010 on how well four products controlled
sandbur in bermudagrass and how much the three post-emergent products
injured the bermudagrass crop. Following is a list of the different
products we used, how well they controlled sandbur and how much crop
injury they caused.

Prowl H2O® (pendimethalin)
This is a pre-emergent product that must be applied before the sandbur
emerge. This is usually in March or very early April. Rainfall must
occur within two weeks of application or efficacy will be reduced
dramatically. We used 2.1 and 3.2 quarts of product per acre in our
study. Sandbur control was rated at 63 and 70 percent, respectively.
This was statistically the same as that provided by the post-emergent
products. Prowl H2O® was not evaluated for crop injury.

Roundup WeatherMax® (glyphosate)
Roundup WeatherMax® is labeled for sandbur control only after the first
cutting of hay on bermudagrass. Application must be made very soon after
hay cutting or crop injury may occur. There is a 28-day grazing and
haying restriction after the herbicide has been applied.
We used two rates of Roundup Weathermax®, 6.5 and 11 ounces per acre.
Sandbur control was rated at 100 percent for each rate. Crop injury in
the form of discoloration and reduced plant height was observed 14 days
after treatment, but the bermudagrass outgrew the injury within 30 days
after treatment. We harvested the plots, and there was no yield
difference between the Roundup WeatherMax® plots and the plots that
didnot receive herbicide.

Pastora® (metsulfuron methyl and nicosulfuron)
Pastora® is a relatively new product that is a mixture of herbicides
trade-named Cimarron® and Accent®. The label requires using the product
when sandbur are less than 2 inches tall and bermudagrass is less than 4
inches tall. There are no grazing or haying restrictions with Pastora®.
We applied Pastora® at rates of 1 and 1.5 ounces per acre. We achieved
sandbur control ratings of 97 and 100 percent, respectively. We saw
visual crop injury soon after treatment, but the bermudagrass largely
outgrew the injury after 30 days. When we harvested the crop 35 days
after application, there was no statistically significant yield difference between
the Pastora® treatments and the plots that did not
receive herbicide.

Panoramic® (imazapic)
Panoramic® is a generic version of a product that was previously sold as
Plateau®. It has both pre-emergent and post-emergent activity, but is
usually more effective when used post-emergent. The label states to not
use Panoramic® on drought-stressed bermudagrass, when bermudagrass is in
the transition stage between dormancy and full green-up, on newly
aerated fields, in the establishment year for bermudagrass or on the variety World Feeder.

We applied Panoramic® at rates of 6 and 12 ounces per acre. Sandbur
control was rated at 100 percent for each rate. However, crop injury was
very severe. Panoramic® caused the worst visual injury symptoms of the
herbicides tested, and the injury carried over into yield. The 6 and 12ounce
rates of Panoramic® caused yield reductions of 41 and 78 percent,
respectively, when harvested 35 days after treatment.

Summary
All the herbicides we tested controlled sandbur. Visual crop injury
symptoms were noted in all the post-emergent treatments 14 days after
treatment, but the visual crop injury symptoms decreased dramatically
when observed 30 days after treatment. Neither Roundup WeatherMax® nor
Pastora® decreased bermudagrass yield when harvested 35 days after
treatment, but Panoramic® applications caused severe yield reductions.
In general, we feel that Prowl H2O® is a good pre-emergent product if
rainfall occurs in a timely fashion after application and that Pastora®
and Roundup WeatherMax® are good post-emergent products if applied in a
timely manner. Although it controls sandbur well, we have difficulties
recommending Panoramic® due to crop injury concerns.
If you have sandburs, now's your chance to plan to get' em next year.

You can find this and past articles on the web at
http://www.mycountrytractor.com/ for your reference. Extension programs
serve of all ages regardless of socioeconomic level, race, color, sex,
religion, disability, or national origin. The Texas A&M University
System, U.S. Department of Agriculture, and the County Commissioners
Courts of Texas Cooperating serve of all ages regardless of
socioeconomic level, race, color, sex, religion, disability, or national
origin. The Texas A&M University System, U.S. Department of Agriculture,
and the County Commissioners Courts of Texas Cooperating


Thank you,

Tommy Neyland
County Extension Agent
Texas Agrilife Extension Service
P.O. Box 188
Centerville, Texas 75833
903.536.2531 phone
903.536.3804 fax