Late summer to early fall may not be the showiest time for dandelions, but it’s the best time to eliminate them from your lawn. I usually avoid using toxic lawn chemicals, so I was curious to try the new Ortho Elementals Lawn Weed Killer sample that I received at the recent Garden Writers Association Symposium in Indianapolis. This broadleaf weed killer is made with naturally occurring iron. The active ingredient is iron HEDTA–or hydroxyethylenediaminetriacetic acid, for those of you studying organic chemistry!
The product works by creating iron toxicity at the cellular level. Because the mechanism of iron uptake is different in broadleaf plants such as dandelion from that in monocots such as lawn grass, the weeds die while the grass is unaffected. This naturally occurring chemical is reported to be safe for humans and other animals. Sprayed areas are safe to reenter as soon as the product dries. And further background research shows that iron HEDTA is not persistent, so it is quite friendly to the environment. Additionally, rather than spraying the entire yard, you’re supposed to spray only the dandelions (or other broadleaf weeds you want to eliminate), so much less chemical is used than with conventional weed killers.
The initial results are impressive. I spot sprayed dandelions in my yard this last weekend. In just 72 hours, they looked like the dandelion in the “after” photo below. The true test will be how much regrowth happens. The label indicates that for best results, two applications three to four weeks apart may be necessary. So I expect that the dandelions will regrow from the roots and need another shot of weed killer to wipe them out entirely.
That golden bane of perfect green lawns may soon earn a place of prominence in the horticultural world. Sure, there are gardeners who occasionally harvest dandelion greens for salads or make batches of homemade dandelion wine, but the plant remains an all-too-common weed despised by most suburban homeowners.
That may all change if researchers at the Fraunhofer Institute in Germany have any say. They’ve discovered how to make lemonade out of lemons, if you will, by harvesting dandelion latex (that white sticky stuff in dandelion stems) to make rubber. The idea isn’t new. During World War II, the Allies experimented with all sorts of alternatives to latex from rubber trees because plantations in Southeast Asia had fallen under control of the Japanese. But dandelion rubber never took off, partly because dandelion latex polymerizes (sets up) when it hits the air. The German researchers have been able to turn off the enzymes that cause polymerization, and in the process, increase dandelion latex yields by 500 percent. Time magazine called it one of the 50 best inventions of 2009.
Healthy rubber trees still produce a lot more latex than a dandelion plant, but a serious fungus is threatening to wipe out commercial rubber production from trees. The disease has already eliminated widespread rubber tree cultivation in South America, and is threatening to do so in Southeast Asia.
Rubber from natural latex is important in making car tires elastic enough to inflate. If latex from rubber trees becomes unavailable, that from dandelions may take its place. Another bonus of dandelion latex–it appears to be less allergenic than latex from rubber trees.
So, next spring if your neighbors complain about the crop of dandelions in your front yard, just let them know that you’re on the cutting edge of technology, and have started your very own dandelion latex plantation.