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Posts Tagged: Weeds

Researchers raise concern over paraquat health risks

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.

Weeds will compete with a new orchard for water, sun and nutrients, and interfere with harvest in mature orchards. Weeds in this orchard were killed with an herbicide.
Posted on Tuesday, March 7, 2017 at 11:16 AM
Tags: Kurt Hembree (1), weeds (7)

Control garden weeds in early spring

UC Cooperative Extension IPM advisor Cheryl Wilen recommends swivel hoes over herbicides for weed control.
Weeds are easiest to control when they are tiny emerging plants, reported Jeanette Marantos in a Los Angeles Times blog post. Marantos got tips on weed management from Cheryl Wilen, UC Cooperative Extension integrated pest management advisor in Southern California.

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.

Posted on Wednesday, April 13, 2016 at 11:21 AM
Tags: Cheryl Wilen (2), weeds (7)

Unwelcome weed 'stinkwort' spreading quickly in California

Invasive weed stinkwort, Dittrichia graveolen, can spread rapidly on overgrazed land, river and stream banks and roadsides.
UC Cooperative Extension experts are advocating for aggressive control of invasive stinkwort to prevent it from becoming an established California weed, reported the Sacramento Bee. Joe DiTamaso, UCCE specialist in the Department of Plant Sciences at UC Davis, said he believes CalTrans will have to treat stinkwort as an invasive of high and unique concern if it has any hope of controlling its spread.

Stinkwort made its first California appearance in 1994, but remained quite rare until the mid-2000s, when it began spreading rapidly. Stinkwort is now found in 36 of the state's 58 counties, particularly along roadsides.

"If it gets a major foothold and produces millions and millions of seeds, then the seedlings will grow and they can form a carpet," DiTomaso said. "Then it would block light and prevent the growth of more desirable species – like native plants. It will out-compete them, and that is a concern."

Another troubling aspect is that the weed has been seen in vineyards, said John Roncoroni, UCCE advisor in Napa County, a weed science expert.

"I've seen it on the roadsides in Napa, and it's just encroaching into the vineyards at Napa Valley College," he said.

Posted on Tuesday, August 13, 2013 at 12:03 PM

Invasive weed threatens California rice

Winged primrose willow grows erect, unlike other waterprimroses, which grow prostrate on the ground.
Winged primrose willow, a weed native to South America, was found last fall in a few Butte County rice fields, alarming agriculture officials about its possible spread to Colusa and Glenn counties, said an article in the Colusa County Sun-Herald.

The weed is highly invasive, produces vast quantities of seeds and survives under a wide range of hydrological and climatic conditions.

"Farmers have to keep an eye out for this weed, and let us know if they think they have it," said Luis Espino, UC Cooperative Extension advisor in Colusa, Glenn and Yolo counties, a rice production expert.

Unlike other waterprimroses, the winged primrose willow can grow within flooded rice fields, which makes it even more problematic for local farmers if it should get established in this area, Espino said.

 

Posted on Friday, April 27, 2012 at 10:25 AM

UC farm advisor outlines problems posed by invasive species

Faber said kudzu (shown above) was introduced as a ground cover, and then took off in the southern U.S.
Invasive plants and insects are proliferating faster than ever, causing massive problems in the environment, UC Cooperative Extension farm advisor Ben Faber told farmers at the Ventura County Research Symposium yesterday, the Ventura County Star reported.

Faber said invasive species are being introduced at a rapid rate around the world, and are primarily spread by humans.

He differentiated between non-native plants that are beneficial, such as avocados and citrus, and invasive plants that have been accidentally introduced into an ecosystem where they run rampant.

"An invasive species is something out of place and out of control," he said.

Fresno State report confirms state’s farmers apply water efficiently
Fresno State press release

Claims that California farmers are wasteful and inefficient in managing their water supplies are inaccurate, according to a new report released by Fresno State's Center for Irrigation Technology.

The study is the culmination of a yearlong effort by irrigation experts to update the 1982 University of California Cooperative Extension report “Agricultural Water Conservation in California with Emphasis on the San Joaquin Valley” by David C. Davenport and Robert M. Hagan.

The new study concludes that the 1982 report correctly framed the potential for agricultural water-use efficiency, and many of its findings are still relevant 30 years later.

Posted on Thursday, November 17, 2011 at 8:55 AM
Tags: Ben Faber (0), invasive weeds (0), water (0)

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