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 (402 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
2015/5/27 16:10:00 - AAA Blue Jays Open Season With Burleigh Grimes Doubleheader
2015/5/27 16:04:44 - NCMC Dean Retires After 27 Years
2015/5/27 15:57:40 - Newtown-Harris Announces Teacher Resignation And Hire
2015/5/27 15:53:30 - Chillicothe Man Injured After Car Strikes Deer
2015/5/27 15:50:42 - Bluegrass Festival Coming To Chillicothe In June
2015/5/27 15:37:24 - Truck/SUV Collision Injures 19-Year Old
2015/5/27 15:32:55 - ATV Accident Sends Marceline Man To Hospital
2015/5/27 15:28:16 - Wednesday Morning Accident Kills Novinger Man
2015/5/27 5:37:33 - Public Input Sought For Poosey Conservation Area Plan
2015/5/27 4:28:16 - Remains of Man Missing More Than 20 Years Found In Submerged Car
2015/5/27 4:12:43 - Missouri Man Dies After Being Bitten In Both Legs By Snake
2015/5/26 5:42:17 - Two Injured In ATV Accident
2015/5/26 4:21:12 - Inmate Sentenced To Life In Prison May Be Free Man This Summer
2015/5/26 4:07:52 - Police: 3 Children Hurt When Water Spout Uproots Bounce House
2015/5/25 5:57:00 - 10 Historical Facts About Memorial Day
2015/5/25 5:46:10 - Forgotten For Decades, Fallen NY Soldier Is Finally Honored
2015/5/22 17:55:36 - Woman Found Pushing Dead 3-Year-Old Son in Swing
2015/5/21 14:21:21 - NCMC Foundation Presents "Salute Awards"
2015/5/21 11:35:05 - Marshall Man, Accused Of Shooting At Police, Captured In Alabama
2015/5/21 11:25:26 - Police Surround Home Of Suspected Murderer In Sedalia
2015/5/21 10:20:00 - Daily Room Rate At Sunnyview Increases By Eight Dollars
2015/5/21 10:20:00 - Milling Work Scheduled To Begin Next Week In Trenton
2015/5/21 10:10:04 - Kansas Truck Driver Injured In U.S. 36 Accident
2015/5/21 10:07:54 - Putnam County Teens Injured In Late Night Accident
2015/5/21 10:00:00 - AP : Suddenlink Sold To European Company
2015/5/21 10:00:00 - Local Bank Purchases Tax Credits, In Hopes Of Improving Trenton's Downtown
2015/5/21 9:47:51 - Efforts Underway To Repair Lawn Damage At Grundy County Courthouse
2015/5/20 10:55:08 - Area Organizations Plan To Distribute Money-Saving Light Bulbs
2015/5/20 10:47:05 - Gallatin Library Receives $5,628 Grant
2015/5/20 10:00:00 - Area Rivals Tie For 3rd At Class 1 Boys Golf Tournament



Bookmark this article at these sites

                   

Listen to KTTN-FM