The popular herbicide paraquat works well and is inexpensive, but emerging research shows a correlation of paraquat exposure and Parkinson's disease, reported Kerry Klein on Valley Public Radio.
Klein met with UC Cooperative Extension weed advisor Kurt Hembree at an almond orchard near Selma that was clear of weeds. Growers kill weeds because weeds kill crops, Hembree said.
"Direct competition for water and nutrients. Whatever the tree likes, the weeds like," he said.
Hembree explained how the paraquat works.
"Paraquat's a contact-type herbicide," he said. "In other words, it's a material that, if you sprayed it on a plant, it'll disrupt the plant's cells. And basically in five or six days, whatever it touches, it spots up and it causes necrosis and death on the tissue."
Paraquat is toxic, so it requires careful handling to protect the safety of applicators.
“Something like paraquat, you're going to wear rubber boots, you're going to wear goggles while you're spraying,” Hembree said. “You don't want to get this stuff on your skin or on your mouth or anywhere.”
The KVPR story said paraquat is among the top 10 most common herbicides in California, and the San Joaquin Valley gets more than three-quarters of the state total. Caroline Tanner, a neurologist at UC San Francisco, was also interviewed for the story.
“People who mixed or applied this chemical had more than double the risk of developing Parkinson's disease compared to people really very similar as far as where they lived, even what they did for a living, age and gender,” she said.
However, people who were careful with personal protective equipment didn't have a greater risk of Parkinson's disease, Tanner said.
Wilen recommends home gardeners use a swivel (or hula) hoe to scrape the surface and decapitate weeds. “It's a bit of exercise,” she said, "but you can do it so quickly, it's not a problem.”
Another weed control strategy is a thick layer of mulch, with does double-duty by reducing water evaporation from the soil surface, thereby conserving water. Wilen suggests a three- to four-inch layer of mulch be spread in garden beds and landscape borders before the weed seeds have a chance to germinate. Mulch blocks the sunlight weeds need to push through the ground.
Fabric weed barriers are useful for controlling particularly challenging weeds, like nutsedge. Wilen suggests covering the fabric with mulch for an esthetically pleasing weed-free garden.
Though the common herbicide glyphosate (such as Roundup) kills weeds and is safe if used correctly, Wilen prefers using the swivel hoe. "It's just quicker and easier than pulling out the spray equipment," she said.
- Author: Brenda Dawson
Reporter Amina Khan with the LA Times profiled husband-and-wife entomologist team Christina and Mark Hoddle of UC Riverside (Mark is also a UC Cooperative Extension entomology specialist). The pair travel the world seeking parasitoids that can serve as biological control to invasive California pests and then test the results at the Center for Invasive Species Research at UC Riverside. "Bugs don't take weekends," Christina Hoddle told the reporter, "so neither do we."
Weed threatens rice-growing areas
Heather Hacking, Chico Enterprise Record
Autumn is for Apples: An Interview With Carol Fall
Jennifer Jewell, aNewsCafe.com
As apple season approaches, this article examines the Trinity Heritage Orchard Project through an interview of Carol Fall, program representative for UC Cooperative Extension Trinity County. The project has identified and mapped century-old apple trees from Gold Rush-era homesteads that are now on public lands and available for gleaning. Fall also evaluates how fruits of these heirloom varieties are best picked and used—whether for baking, cider-making, eating fresh or storing for winter months—and takes cuttings from the most significant varieties to plant elsewhere in the community. The article says Fall will provide apple samples Oct. 8 at Weaverville's annual Salmon Festival.
In the 8-minute segment, which runs from about 23:50 to 31:30 in the hour-long show, Hanson outlined Cooperative Extension weed management research.
"Weeds are a tremendous problem for farmers in every cropping system," Hanson said. "In contradiction to some other pests, weeds don’t spike. They are a constant problem. Farmers are spending money on weed control and trying to minimize productivity declines from weeds competing for water, fertilizer and sunlight."
Hanson said much of UC's weed research looks at chemical control, the approach used by 85 percent of farmers.
"We try to find the most efficient rates, most effective chemicals, and the least environmentally damaging products," he said.
Callison seemed intrigued by the fact that weed seeds can lie dormant in soil for years and even decades.
"It is said, one years seeding is 10 years weeding. That’s probably an underestimate," Hanson said.
For automated, mechanical weed control to work, scientists must teach machines how to distinguish between unwanted vegetation and the crop being cultivated. A new, high-tech system using x-rays to detect tomato stems is under development by UC Davis Cooperative Extension agricultural engineer David Slaughter and USDA Agricultural Research Service researcher Ron Haff. The output from the x-ray detector is input to a microcontroller that controls a pair of pneumatically powered mechanical weed knife blades.
Slaughter and Haff's work was explained this week in an online newsletter produced by Vision Systems Design, an organization that provides automation solutions for engineers and integrators worldwide.
The mechanical weeding machine includes an x-ray mounted to the side of a shielded tunnel that is pulled behind a tractor over the row of tomato plants. As the x-rays radiate across the tunnel, they are detected by an array of 32 photodiodes whose output is tied to a single point at the input of a summing amplifier, the story says.
The system was used in field trials on a 15-meter row containing 39 standing tomato seedlings. At a speed of about 1 mile per hour, the detection system identified all 39 stems of standing plants with no false positives.