Dandelions Overtake Lawns, Weed Killers Abound
Herbicide Applied in Fall Offers Best Chance for Lasting Control
May 9, 2009
Unless you are into dandelion wine, controlling this perennial turf weed becomes a top priority for lawn aficionados.
“The dandelion is certainly the most recognizable of all weeds flowering in our lawns and folks certainly have different perspectives on them,’’ said Kevin Frank, professor of Crop and Soil Sciences at Michigan State University.
There are even websites devoted to dandelions, including Dandelion Watch .
Most lawn enthusiasts do not have a favorable perspective on the tap-rooted perennial, known for pretty yellow flowers followed by globe-like, grayish white seed heads.
Flowers are produced from May to June followed by a second flowering period in autumn when the day length is less than 12 hours.
Dandelion Destruction
Each spring, legions of homeowners apply a weed and feed fertilizer hoping to control broadleaf weeds such as the dandelion. It is an admirable pursuit, though misguided, said Ron Calhoun, a turf expert at Michigan State University.
“Fall is absolutely the best time to control weeds, including dandelions,’’ Calhoun said. “They are no longer growing and instead are storing food for next spring.’’
Rather than pushing out growth, weeds begin pulling in nutrients to store in the roots. A herbicide applied in early October is drawn into the roots, but death does not come until six months later.
Once the weed breaks dormancy in spring, it draws energy from its roots to push out new growth. The root-stored herbicide moves up through the plant and kills it, Calhoun explained.
Spring Vs. Fall
Herbicides applied only in spring may set the weed back, as evidenced by twisting and curling, put it likely will survive, Calhoun said. “It has enough energy stored in the roots to push out another flush of growth,’’ Calhoun said.
Frank last autumn followed his own advice on controlling weeds, including dandelions, by applying a broadleaf herbicide to his lawn in October.
“This spring the results were pretty impressive, except for that strip I missed with the sprayer,’’ Frank said.
Dandy Dandelions
There are scores of annual and perennial weeds that establish themselves in turf grass, but the dandelion is among the most recognized and is widespread throughout North America. It tolerates many types of soil, from loose sand to compacted clay. Seeds are dispersed by wind, so people living near fields are especially prone to dandelion infestation.
People intent on fighting dandelions this spring can try digging them out, but be sure to get the entire tap root or the weed will come back.
Frank said you can also use a herbicide once dandelions reach the puff-ball stage, but don't expect great results.
"If you enjoy the color or like dandelion wine, just let them thrive and worry about it this fall,' Frank said.
