User Login    
 + Register
News : Cool Weather Slows Weed Burndown, Spray When Warm Says MU Specialist
Posted by Randy on 2014/4/15 4:48:57 (465 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
2015/8/28 17:19:39 - Missouri Highway Patrol Trooper Killed Audrain County Accident
2015/8/28 4:26:43 - Harrison County Man Arrested For Child Pornography
2015/8/28 4:14:50 - Opponents Of Missouri Hog Farm Win Court Ruling
2015/8/28 4:09:36 - Police Escort Fills In For Dad On First Day Of Kindergarten
2015/8/28 4:04:09 - Northeast Missouri Suspect Badly Hurt After Police Shooting
2015/8/28 4:00:11 - New Missouri Court Fines, Sex Ed Laws Set To Take Effect Today
2015/8/28 3:54:40 - Police Say Woman Found Getting High On Canned Air At Walmart
2015/8/27 14:18:52 - Milan Wildcat Coaches Shows For Thursday, 8/27/15
2015/8/27 13:50:00 - Trenton Lady Bulldogs Win Home Opener At Riverside CC
2015/8/27 12:10:32 - Trenton Tennis Beats Carrollton, 7-2
2015/8/27 11:59:59 - Lawson Sweeps Trenton In Tuesday Volleyball
2015/8/27 10:41:46 - Brookfield Downs Trenton In Head-To-Head Golf Duel
2015/8/27 8:40:00 - Grundy County Circuit Court News
2015/8/27 6:40:00 - Freightliner Truck Swerves To Avoid School Bus
2015/8/27 6:25:13 - Trenton Hy-Vee Honors Joel McCully With Legendary Customer Service Award
2015/8/27 4:14:05 - Suspect Charged In Naked Home Invasion In Maryville
2015/8/27 4:09:17 - Missouri Couple Accused Of Multistate Sex Trafficking
2015/8/27 4:03:09 - Missouri Man Convicted Of Raping 13-Year-Old Dies In Prison
2015/8/27 3:58:37 - More Than Two Dozen Arrests Made At Independence Motels
2015/8/27 3:54:33 - Burger King To McDonald's: Lets Make A McWhopper
2015/8/27 3:50:03 - Two Children Removed From Rat Infested, Feces Filled Home
2015/8/26 11:20:00 - Princeton Tiger Coaches Shows For Wednesday, 8/26/15
2015/8/26 9:11:31 - Spickard Fall Festival Schedule Announced
2015/8/26 9:07:42 - Trenton City Council Meeting Results
2015/8/26 7:41:02 - Two Reporters Killed On Live Television
2015/8/26 6:23:52 - Gallatin City Council Approves Tax Levy
2015/8/26 6:20:00 - Building And Nuisance Board Add Additional Properties To Nuisance List
2015/8/26 6:00:00 - Grundy County Sheriff Reports Two Arrests
2015/8/26 5:50:00 - Fire Safety Fire Officer One Course To Be Hosted By Trenton Fire Department
2015/8/26 5:42:41 - Texas Man Accused Of Multiple Violations After Accident Near Bethany



Bookmark this article at these sites

                   

Listen to KTTN-FM