The Mountain Stewards recently hosted a panel discussion at Signal Mountain Library concerning the effects of chemical fertilizers and weed killers on our bodies and the environment, and panelists offered a host of tips for people interested in improving their own health as well as that of their yards.
Ann Brown, a member of the Tennessee Valley Chapter of Wild Ones, an organization focused on gardening with native plants, discussed pesticides that are harmful to pollinators and the dangers of a weed-free lawn.
Pesticides, which include herbicides, insecticides and fungicides, are the major culprits behind the 40-percent decline in insects worldwide and the near-extinction of 40 percent of the world's insect pollinators, she said. In addition to pollinating plants, invertebrates such as insects perform beneficial functions such as cleaning water and aerating and creating soil, Brown explained. Honeybees have also declined by 50 percent in the past 20 years, and one of the causes is pesticides, she said.
Brown said neonicotinoids are the type of pesticide most harmful to the environment. Initially deemed "bee-safe," neonicotinoids are used extensively in the Midwest on corn and soybean crops. Since neonicotinoids are water-soluble, they can be sprayed, used to treat seeds or injected into the soil — making all parts of the plant toxic to insects.
Imidacloprid is the most commonly used neonicotinoid, and the most toxic to pollinators, said Brow, adding that. European studies have shown the pesticide affects invertebrates and birds through the water system. She said Europe was the first to ban the pesticide, fearing the effect it would have on citizens' health and the related costs that would be borne by its national health care systems.
Signal residents whose hemlocks have been treated to kill the invasive woolly adelgid may be aware that neonicotinoids are used to get rid of the pest, which threatens the area's hemlocks with extinction. Treating hemlocks with a neonicotinoid drench will affect any flowering plants in the yard for seven years, which drops to three years if the tree is sprayed or painted with the pesticide, said Brown.
She noted that the plants people buy from nurseries are typically treated with neonicotinoids in the greenhouses where they're grown, though several local nurseries offer some that aren't, she said.
"If you want to do a pollinator garden or a yard that's good for wildlife, make sure it's not treated with neonics," said Brown. "If you quit using pesticides, your yard will balance."
Lyn Rutherford, landscape inspector with the city of Chattanooga, warned attendees of the harmful effects that using chemicals in yards, gardens, golf courses, parks and roadways has on water quality.
She encourages people who hire others to do their landscaping to question them about what they're spraying on their lawn, explaining that what is put on our yards directly correlates with the quality of our water.
Like asphalt, yards don't infiltrate stormwater like the forest floor. So if you do use fertilizers or pesticides, don't do so when it's about to rain or the chemicals will go straight into the water supply. Rutherford also advises adding buffer plants by creeks to help infiltrate water and break down pollutants.
The worst pollutant is sediment, she said, which clogs drains underneath roads and makes it difficult for aquatic wildlife to breathe. To keep sediment out of the water, she suggests taking erosion-prevention measures in bare spots in your yard.