Friday, June 19, 2015
One of the cool things about agricultural technology is that it gets both more effective and safer over time.
Agricultural chemical manufacturers are developing products that have much shorter lives—that break down far more quickly and don’t persist in the environment nearly as long as earlier products.
“Contrary to the one-dimensional view of pesticides as broad-spectrum and persistent, recently developed insecticides are highly selective for insect pests,” write the authors of a report on potential pesticides.
I chatted with a South Illinois corn and soy farmer last week. His 1,500-acre family farm has virtually stopped using insecticides—which were extensively used a generation ago.
He said the use of insect-killing chemicals on his farm has been made unnecessary by stacked traits that put varieties of the Bacillus thuringiensis into the seed—so the plant itself prevents insect attack and chemical sprays are unnecessary.
It has the additional benefit of impacting only those insects actually feeding on the crop. Other insects in the environment are not impacted.
He still uses herbicide, but generally in just two applications annually. His farm has gone to no-till agriculture, and he applies glyphosate herbicide once to kill off the spring growth, and most years one second application later in the year is all that is necessary. Sometimes the second application is avoided.
He said that when he started farming half a century ago, the chemicals were heavily used and were dramatically toxic or caustic. His overall use of chemical additives is down dramatically, and his soil is healthier than it was, he said.
This farmer said he’s a believer in technology. It made his farm profitable, and something his two adult sons are interested in taking over.
One of the interesting features about some new insecticides is that they’re patterned after natural products. Bacillus thuringiensis is a natural soil-born bacterium. By inserting the effective sections of Bt’s genome into agricultural plants, the plants are provided with the ability to protect themselves.
Some researchers are now looking at another natural product, tarantula venom, as a potential agent for pesticides.
It turns out tarantula venom isn’t only scary to humans, but very effective against the cotton bollworm and other insects. And they don’t have to be stung; they can be killed from eating it.
There are cautions here, though. since some of these biopesticides or “botanicals” may actually be more toxic in the environment than their synthetic cousins.
“Synthetic pesticide use has been the dominant form of pest control since the 1940s. However, biopesticides are emerging as sustainable pest control alternatives, with prevailing use in organic agricultural production systems,” write the authors of the paper, “Bioinsecticide-Predator Interactions: Azadirachtin Behavioral and Reproductive Impairment of the Coconut Mite Predator Neoseiulus baraki.”
They warn that while natural and approved for organic farming, azadirachtin has certain toxicity issues. The authors note that 70 percent of synthetic insecticides have natural analogs, but that the natural ones are not always safer.
Azadirachtin, which is approved for organic farming, is derived from the seeds of the neem tree. One concern is that its use as an insecticide can screw up the natural relationship between problem insects and their natural predators—since the predators are also impacted by the insecticide.
The used of the product “may lead the predators to leave the area, compromising the biological control,” and ultimately making farmers more reliant on chemicals.”
Clearly, this stuff is complicated, but it’s heartening that as more study occurs, we’re understanding relationships better and developing better agricultural controls.
© Jan TenBruggencate 2015