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Crabgrass’ secret: The despised weed makes herbicide to kill neighboring plants

June 26, 2013 — Contrary to popular belief, crabgrass does not thrive in lawns, gardens and farm fields by simply crowding out other plants. A new study in ACS’ Journal of Agricultural and Food Chemistry has found that the much-despised weed actually produces its own herbicides that kill nearby plants.

Chui-Hua Kong and colleagues point out that crabgrass is not only a headache for lawns and home gardens, but also a major cause of crop loss on farms. Scientists long suspected, but had a hard time proving, that the weed thrived by allelopathy. From the Greek “allelo-,” meaning “other,” and “-pathy,” meaning “suffering,” allelopathy occurs when one plant restricts the growth of another by releasing toxins. They set out to determine if crabgrass has this oppressive ability.

Kong’s team isolated three chemicals from crabgrass that affect the microbial communities in nearby soil and did indeed inhibit the growth of staple crops wheat, corn and soybeans. “The chemical-specific changes in [the] soil microbial community generated a negative feedback on crop growth,” the scientists said, noting that the chemicals also would have a direct toxic effect on other plants.

The authors acknowledge funding from the National Natural Science Foundation of China.

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Story Source:

The above story is reprinted from materials provided by American Chemical Society.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Bin Zhou, Chui-Hua Kong, Yong-Hua Li, Peng Wang, Xiao-Hua Xu. Crabgrass (Digitaria sanguinalis) Allelochemicals That Interfere with Crop Growth and the Soil Microbial Community. Journal of Agricultural and Food Chemistry, 2013; 61 (22): 5310 DOI: 10.1021/jf401605g

Note: If no author is given, the source is cited instead.

ScienceDaily: Agriculture and Food News

‘Trojan Horse’ Antimicrobial Seeks to Kill Pathogens Through Direct Food Contact

A computerized illustration of SDC attacking a microorganism.

An antimicrobial product used to disinfect and sanitize food contact surfaces in the restaurant and manufacturing industries is now being tested directly on food and has shown a “materially significant reduction” in Salmonella contamination on poultry.

That’s according to Hank Lambert, CEO of PURE Bioscience Inc. of El Cajon, CA, the company that created and patented its silver dihydrogen citrate (SDC) product about a dozen years ago. SDC is a colorless, odorless and low-toxicity liquid containing silver ions, citric acid, water and other ingredients.

Bacteria respond to the citric acid as a food source, and the active ingredients in SDC then cause irreversible damage to the microorganism’s DNA, reproductive functions stop, and the organism dies. The company claims that its product has 30-second bacterial and viral kill times and 24-hour residual protection.

Salmonella is a serious problem in the poultry industry, and infection from the bacteria is a common source of foodborne illness. The U.S. Centers for Disease Control and Prevention estimates there are 1.2 million illnesses linked to Salmonella bacteria each year, with about 23,000 hospitalizations and 450 deaths.

PURE® Hard Surface is registered with the U.S. Environmental Protection Agency for food surface decontamination applications, and SDC has been determined Generally Recognized as Safe (GRAS) for use as a biocide on food processing equipment, machinery and utensils. Besides Salmonella, the company notes that the SDC formula in PURE® Hard Surface is also effective on hazardous food pathogens such as E. coli and Campylobacter, as well as on a several types of viruses and fungi.

PURE Bioscience’s new product, as yet unnamed, along with test results and other information, is about to be submitted to the U.S. Food and Drug Administration and the U.S. Department of Agriculture for potential regulatory approval for direct food contact as a processing aid for poultry.

Lambert told Food Safety News that Dr. James Marsden of Kansas State University’s Animal Science and Industry faculty has tested the SDC formula on poultry and is now embarking on additional tests of the product on produce (lettuce, cilantro and spinach) and meat (beef, pork, lamb and veal).

“The results showed that the combination of treatments has the potential to reduce Salmonella on raw poultry products to levels below the detection limit when SDC is included in the process,” notes a company statement.

Marsden will be preparing the submissions to USDA and FDA, which the company indicates would be made before the end of May.

“These are specific approvals for specific food groups,” Lambert explained. “We would have to go through the [Food Contact Notification] process for produce and for the other meats. We might use different applications and dilutions.”

PURE Bioscience has recently been repositioning itself to focus more on the food industry, said Lambert, who previously managed the food safety services business for Underwriters’ Laboratories (UL) and has also worked as a food industry and consumer products executive. He joined the company as CEO this past September in order to move the new agenda forward.

“I was instantly attracted and interested in a food safety solution to take antimicrobial applications in the food industry to the next level and provide an increased level of protection against the pathogens that are so persistent throughout the food industry,” he said.

Lambert said the next step would be arranging for pilot plant testing in USDA-inspected poultry processing plants. If everything goes well, he said that federal agency regulatory approvals could be in place by the end of the year.

Food Safety News

Common crop pesticides kill honeybee larvae in the hive

Four pesticides commonly used on crops to kill insects and fungi also kill honeybee larvae within their hives, according to Penn State and University of Florida researchers. The team also found that N-methyl-2-pyrrolidone (NMP) — an inert, or inactive, chemical commonly used as a pesticide additive — is highly toxic to honeybee larvae.

“We found that four of the pesticides most commonly found in beehives kill bee larvae,” said Jim Frazier, professor of entomology, Penn State. “We also found that the negative effects of these pesticides are sometimes greater when the pesticides occur in combinations within the hive. Since pesticide safety is judged almost entirely on adult honeybee sensitivity to individual pesticides and also does not consider mixtures of pesticides, the risk assessment process that the Environmental Protection Agency uses should be changed.”

According to Frazier, the team’s previous research demonstrated that forager bees bring back to the hive an average of six different pesticides on the pollen they collect. Nurse bees use this pollen to make beebread, which they then feed to honeybee larvae.

To examine the effects of four common pesticides — fluvalinate, coumaphos, chlorothalonil and chlorpyrifos — on bee larvae, the researchers reared honeybee larvae in their laboratory. They then applied the pesticides alone and in all combinations to the beebread to determine whether these insecticides and fungicides act alone or in concert to create a toxic environment for honeybee growth and development.

The researchers also investigated the effects of NMP on honeybee larvae by adding seven concentrations of the chemical to a pollen-derived, royal jelly diet. NMP is used to dissolve pesticides into formulations that then allow the active ingredients to spread and penetrate the plant or animal surfaces onto which they are applied. The team fed their treated diet, containing various types and concentrations of chemicals, to the laboratory-raised bee larvae.

The team’s results are reported in the current issue of PLoS ONE.

“We found that mixtures of pesticides can have greater consequences forlarval toxicity than one would expect from individual pesticides,” Frazier said.

Among the four pesticides, honeybee larvae were most sensitive to chlorothalonil. They also were negatively affected by a mixture of chlorothalonil with fluvalinate. In addition, the larvae were sensitive to the combination of chlorothalonil with the miticide coumaphos. In contrast, the addition of coumaphos significantly reduced the toxicity of the fluvalinate and chlorothalonil mixture.

According to Chris Mullin, professor of entomology, Penn State, these pesticides may directly poison honeybee larvae or they may indirectly kill them by disrupting the beneficial fungi that are essential for nurse bees to process pollen into beebread.

“Chronic exposure to pesticides during the early life stage of honeybees may contribute to their inadequate nutrition or direct poisoning with a resulting impact on the survival and development of the entire bee brood,” he said.

The researchers note that fluvalinate and coumaphos are commonly used by beekeepers on crops to control Varroa mites, and are found to persist within beehives for about five years. Chlorothalonil is a broad-spectrum agricultural fungicide that is often applied to crops in bloom when honeybees are present for pollination because it is currently deemed safe to bees. Chlorpyrifos is a widely used organophosphate in crop management.

“Our findings suggest that the common pesticides chlorothalonil, fluvalinate, coumaphos and chloropyrifos, individually or in mixtures, have statistically significant impacts on honeybee larval survivorship,” Mullin said. “This is the first study to report serious toxic effects on developing honeybee larvae of dietary pesticides at concentrations that currently occur in hives.”

The team also found that increasing amounts of NMP corresponded to increased larval mortality, even at the lowest concentration tested.

“There is a growing body of research that has reported a wide range of adverse effects of inactive ingredients to human health, including enhancing pesticide toxicities across the nervous, cardiovascular, respiratory and hormone systems,” Mullin said. “The bulk of synthetic organic chemicals used and released into U.S. environments are formulation ingredients like NMP, which are generally recognized as safe. They have no mandated limits on their use and their residues remain unmonitored.

“Multi-billion pounds of these inactive ingredients overwhelm the total chemical burden from the active pesticide, drug and personal-care ingredients with which they are formulated. Among these co-formulants are surfactants and solvents of known high toxicity to fish, amphibians, honey bees and other non-target organisms. While we have found that NMP contributes to honeybee larvae mortality, the overall role of these inactive ingredients in pollinator decline remains to be determined.”

Other authors on the paper include Wanyi Zhu, graduate research assistant in entomology, Penn State, and Daniel Schmehl, postdoctoral associate in entomology and nematology,University of Florida.

The National Honey Board, the U.S. Department of Agriculture-National Institute of Food and Agriculture-Agriculture and Food Research Initiative-Coordinated Agricultural Projects and the Foundational Award programs funded this research.

Story Source:

The above story is based on materials provided by Penn State. The original article was written by Sara LaJeunesse. Note: Materials may be edited for content and length.

Agriculture and Food News — ScienceDaily

Industry’s Secret Plan to Get the Feds to Kill GMO Labeling in Every State

With the disappointing results now in from I-522, the initiative in Washington state that would have required labeling of genetically engineered food (aka, GMOs), the looming question is, what’s next? At least for the junk-food lobby, that answer in painfully clear: stop this state-level movement at any cost.

In last Wednesday’s New York Times, Stephanie Strom reports on the dirty details contained in industry documents that I obtained from the Washington state attorney general’s office in the wake of a lawsuit brought against the Grocery Manufacturers Association for illegally concealing donors to the “No on 522″ campaign.

As I explained back in February, the food industry’s ultimate game plan to stop the bleeding in the state-by-state onslaught of GMO labeling efforts is to lobby for a weak federal law that simultaneously preempts or trumps any state-level policy. While we have known that industry would want to put an end to the public-relations nightmare happening state by state, this document for the first time reveals the lobbyists’ specific strategy.

The details are even worse than I thought and give new meaning to the word “chutzpah.” I had predicted a federal compromise, where industry would agree to a weak form of labeling in exchange for stripping state authority. But what industry wants instead is to stop state laws to require labeling, while not giving up anything in return. In their own words, the game plan is to “pursue statutory federal preemption which does not include a labeling requirement.”

Let me repeat that: The junk food lobby’s “federal solution” is to make it illegal for states to pass laws requiring GMO labeling. Period. End of story.

This is not the way preemption is supposed to work. A quick primer: preemption simply means that a higher law trumps a lower law, so federal trumps state, and state trumps local. This is often the most economically feasible policy approach for business. But it’s also industry’s way of ensuring uniformity and stopping a movement in its tracks.

Here is the pattern: a grassroots movement builds over time to enact local or state laws to protect public health or increase the minimum wage or some other social goal, and industry fights these efforts for years, until they can no longer win. At that point, corporate lobbyists either get their own weak bill passed or work with advocates to pass a compromise version. In exchange, this new law will preempt or prevent any state or city from passing a different or stronger law. It will also negate any law already passed. Forever.

But usually, there is some underlying legal requirement that industry must follow for the concept of preemption to even make sense. The idea is to require some action by industry, with the trade-off for companies to follow one standard instead of 50. Take menu labeling in chain restaurants as a good example. For that issue, there was also a grassroots movement in both states and cities around the nation. So when the National Restaurant Association had enough of fighting those bills, the lobbying group agreed to a federal compromise to require only calorie counts (a weak standard) in exchange for preemption; that is, not allowing any state or local laws to go further. In fact, the Grocery Manufacturers Association itself endorsed this plan.

But, in the current GMA chutzpah scenario, the federal government would outlaw states from enacting GMO labeling, while food makers would not have to label their products. In other words, industry would stop the grassroots movement and not have to pay any price.

Now that the junk food lobby’s true agenda has been revealed, our federal representatives and officials are on notice: the food movement will be holding you accountable to ensure that this democracy-killing power grab does not come to fruition.

You can read the entire set of documents from GMA here. Much of the text is redacted, a sign that industry has a lot more to hide.

Food Safety News