If you’ve noticed some odd development on your tomato plants or rose bushes in northeast Johnson County this spring, you’re not alone.
Horticulturist and tomato breeder Keith Mueller says he’s seen more plants that usual this year showing signs of exposure to herbicides typically used to kill common lawn weeds.
“I’ve seen it all across the city and out in the fields in the country, too,” Mueller said. “You’ve seen it more and more the past 15 years or so, but it’s pretty widespread this year. You rarely ever saw it back then.”
Mueller attributes the damage, which manifests as twisted and curled leaves and stems on tomato plants, to exposure to the chemicals 2,4-Dinitrophenylhydrazine (2,4-D) and Triclopyr. Two decades ago, these weed killers were typically sold to consumers in amine-based formulations, which bound up the active ingredients in a relatively stable compound and slowly released them over a period of a few weeks. But versions of the products that delivered the active ingredients using the more volatile chemical ester as a base became popular among consumers who wanted to see results quickly.
The active ingredients in these products affect the cell structure and growth not only of common yard weeds, but also of a number of garden plants, from tomatoes and roses to grape vines and viburnum. What’s more, the compounds travel easily via air currents, and can spread for long distances.
“It can drift for hundreds of feet, even miles, if winds are right,” Mueller said.
Mueller noted that as these ester-based compounds have become more common, he’s seen more and more of the telltale signs of exposure in area tomato crops. He spotted signs of exposure to 2,4-D on plants at a commercial nursery in the area recently and posted a video of it on Twitter:
— KC Tomato (@kctomato) June 12, 2017
Ward Upham of the Kansas State University Extension’s master gardeners program said his group gets calls about this kind of plant damage every year, but that it may be more widespread than normal in 2017 on account of the above-average temperatures and early spring weather.
“When it’s warm and humid, that affects the volatility [of the ester-based weed killers],” Upham said. “Plus people have probably had their tomatoes out earlier than usual because of the warm weather.”
Damage from the chemical exposure can be mild, in which case the plant simply “grows out” of the phase, or severe, in which the plant dies.
While Upham said that studies have failed to detect traces of the chemicals in tomatoes that set on plants that have shown signs of damage, “that might not be the case if whoever was spraying used way too much.”