User Login    
 + Register
PDQ Cleaning
News : Cool Weather Slows Weed Burndown, Spray When Warm Says MU Specialist
Posted by Randy on 2014/4/15 4:48:57 (272 reads) News by the same author

COLUMBIA, Mo. – Weed control at spring planting, an increasing challenge with herbicide-resistant weeds, presents extra concerns when temperatures stay low, day and night. Weather bears watching more than usual.
Click to see original Image in a new window

Kevin Bradley, University of Missouri weed specialist, knows how to control weeds when warm weather makes plant biology work.

When spring air temperatures rise above 60 F and don’t drop to frosty levels at night, the plants, including weeds, grow rapidly.

With normal temperatures the leaf pores open and plant juices flow. That’s good for weed control.

Many burndown herbicides applied prior to planting depend on that biology. Sprayed on the leaves, the herbicides “translocate.” That is, they move from leaf to root, where the chemistry kills the plant. Weeds are controlled.

Bradley normally urges growers to apply weed control early in the season. That catches weeds just after seedling stage, when they’re small and vulnerable. Small weeds require less herbicide.
This spring, weather has not cooperated. Days above 60 F have been rare. And many nights drop well below 40 F. The weed seedlings are there, but their biology is not in overdrive as usual this time of year.

When temperatures drop below 40 F, weed control falters.

Any burndown application, including glyphosate, requires systemic action, Bradley says. The herbicide needs time to penetrate leaf cuticles and move in the plant for optimum effect.
“Weed control will be poor if you make a burndown application and extended cool, cloudy weather follows. That’s an extra concern if temperatures drop below 40 F.”

Bradley, with help of MU climatologists, looked at April daily temperature cycles across mid-Missouri. Temperatures were lowest 3 to 6 a.m. They reached peaks at 2 to 3 p.m.

Over the last 14 years, records show April temperatures dropped below 40 F as much as a third to half the days, depending on location.
Burndown failures have been common when temperatures drop below 40 F, Bradley adds. “Failure was most likely directly related to air temperature at or after application.”

Variations occur among herbicides and among weeds. This makes management difficult. “There have been few studies on temperature impact on control,” Bradley says.

He advises farmers ready to apply burndown to watch local forecasts closely.

“Wait for favorable temperatures,” he says. “We realize this isn't always possible. Decision must be balanced by size of weeds at time of application. Size may determine decisions. You can’t wait so long that weeds exceed the best size for control. This can happen quickly with horseweed and giant ragweed this time of year.”
Weed control concerns increase when cover crops were grown on cropland over winter. Cool weather increases risk of failed control. Those beneficial plants become weeds in the next crop.

“If you realize you must spray in cool weather, you may want to increase the rate of glyphosate or whatever burndown herbicide you use.”

To improve control, add at least one other tank-mix partner to ensure better success.

Even with low overnight temperatures in the forecast, apply at the time of peak warmth and sunshine in the afternoon. That is when best growth and translocation occur. Avoid early mornings and later afternoons.

“Realize you are not the only one,” Bradley says. “I get lots of calls about when to spray in this cool weather.”

Printer Friendly Page Send this Story to a Friend Create a PDF from the article


Other articles
2014/10/31 13:20:00 - Milan Coaches Show For Thursday, 10/30/14
2014/10/31 9:42:05 - KC Royals Acquire Minor League Catcher
2014/10/31 7:40:47 - PSC Cold Weather Rule Takes Effect November 1
2014/10/31 7:33:53 - MoDOT To Hold Winter Readiness Drill
2014/10/31 6:31:42 - Trenton Police Department Offers Halloween Safety Tips
2014/10/31 4:35:51 - Halloween Is A Dangerous Night For Impaired Driving
2014/10/31 4:26:18 - Student Threatens To Bring Gun To School; Lack Of Communication Upsets Parents
2014/10/31 4:21:03 - Ameren To Lower Gas Rates For Missouri Customers
2014/10/31 4:12:03 - Elderly Man Shoots Woman Who Kicked In Door
2014/10/31 4:07:35 - Trenton Woman Arrested On Violation Of Probation
2014/10/31 4:05:02 - Unity Road To Be Closed For Railroad Crossing Work
2014/10/30 10:19:14 - 11 Men Sentenced In International Child Porn Ring
2014/10/30 10:07:13 - Plane Crashes Into Building At Airport In Wichita, Kansas
2014/10/30 9:22:06 - Grundy County Circuit Court News
2014/10/30 9:19:12 - Summit Natural Gas To Raise Rates
2014/10/30 9:13:29 - Chillicothe Police Make Additional Arrest In Drug Investigation
2014/10/30 4:40:00 - Mother Upset After School Vaccinates Her Child Without Her Permission
2014/10/30 4:36:29 - Illinois Teacher Calls Jamaican Students "N" Word After They Object To 'Afro-American'
2014/10/30 4:09:13 - Kirksville Teen Arrested For Child Molestation
2014/10/30 4:02:02 - Missouri Inmate Indicted For Killing Cellmate
2014/10/30 3:59:21 - Wentzville Parents Charged In 10-Week-Old's Death
2014/10/29 12:36:00 - "Mr. Mizzou" John Kadlec Passes Away at 86
2014/10/29 12:33:08 - NCMC Announces Cancellation of "Meet the Pirate" Night
2014/10/29 12:28:54 - Pre-Season Parent Meeting Approaches For THS Wrestlers
2014/10/29 12:24:51 - Alex Smith Suffers Shoulder Injury
2014/10/29 12:19:43 - 7th Heaven : Royals Push World Series To Dramatic Final Game
2014/10/29 10:40:56 - Health Fair To Be Held Saturday In Mercer County
2014/10/29 10:38:44 - Solar Farm, Electric Rates Topic Of Trenton Board Of Public Works
2014/10/29 10:36:41 - Program On Ebola To Be Presented Saturday In Chillicothe
2014/10/29 10:34:22 - Chillicothe Police Department Makes Arrests On Drug Charges



Bookmark this article at these sites

                   

Listen to KTTN-FM