User Login    
 + Register
TV Banner
News : Cool Weather Slows Weed Burndown, Spray When Warm Says MU Specialist
Posted by Randy on 2014/4/15 4:48:57 (231 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
2014/8/30 0:20:00 - Lexington Runs Over Trenton, 34-6
2014/8/29 16:07:54 - "Kaleidoscope Run" To Start Homecoming Week At THS
2014/8/29 15:51:13 - Trenton, In Return To Class 2, To Host District 16 Softball Tournament
2014/8/29 15:36:48 - Trenton Golfers Take Fifth Place At Lafayette Tournament
2014/8/29 15:32:52 - Drive One For Your School Event To Raise Money For Three Area School Districts
2014/8/29 15:27:34 - Princeton Chamber To Meet Concerning Cow Palace Repairs
2014/8/29 15:23:47 - NFL Suspends Former Mizzou Standout Aldon Smith For Nine Games
2014/8/29 15:21:23 - KC Chiefs Lose Preseason Finale, 34-14 At Green Bay
2014/8/29 15:00:00 - KC Royals Claim Veteran Jayson Nix Off Waivers
2014/8/29 10:05:43 - Lawson Softball Tips Chillicothe, 3-2
2014/8/29 9:51:45 - Truman State Hoops Coach Leaves For Pro Job
2014/8/29 9:50:00 - CHS Lady Hornet Volleyball Opens Season With Sweep Of Trenton
2014/8/29 9:40:04 - Softball Scoreboard : Gallatin Tips Milan 2-1
2014/8/29 9:22:50 - Savannah Tennis Beats Trenton, 8-1
2014/8/29 7:28:34 - Amber And Jim Shippen Latest Contributors To WMH Foundation
2014/8/29 6:20:30 - Hamilton Resident Life Flighted After Accident South Of Cameron
2014/8/29 5:21:37 - Trenton Downtown Improvement Association Approves Loans For Building Projects
2014/8/29 4:35:36 - Crews In Hazmat Suits Search Springfield Home For Ricin
2014/8/29 4:27:55 - Suspect In 6-Year-Old's Death Charged With First-Degree Murder
2014/8/29 4:23:52 - Missouri Unveils Aid Effort To Ferguson Businesses
2014/8/29 4:19:11 - Cat-Astrophic Revelation Purr-Turbs Hello Kitty Fans
2014/8/29 4:15:39 - 4-Year-Old Expelled Over His Mother's Facebook Post
2014/8/29 4:10:25 - Date Set For Local Recount On "Right To Farm" Issue
2014/8/29 4:03:50 - One Injury In Accident West Of Trenton
2014/8/28 15:01:25 - KC Royals Turning Back Clock To 1974
2014/8/28 14:50:00 - Milan Coaches Shows For Thursday, 8/28/14
2014/8/28 12:50:00 - Chillicothe Hornets Have Dominant Tennis, Golf Performances
2014/8/28 12:32:42 - KC Royals Urge Fans To "Wear Blue" For Rare Sunday Night Game
2014/8/28 12:27:24 - KC Royals Place Top Prospect Starling In Arizona Fall League
2014/8/28 12:21:45 - Brookfield Wins Extra-Inning Showdown With Penney, 3-2



Bookmark this article at these sites

                   

Listen to KTTN-FM