Pesticide-resistant weeds closing in on Pennsylvania
live.psu.edu/story/56464#nw69
Friday, November 18, 2011
Credit: USDA Early growth stage of water-hemp, a weed that is becoming resistant to certain herbicides.
UNIVERSITY PARK, Pa. — The challenge of weeds that have become resistant to glyphosate — the active ingredient in Round-Up herbicide — has become an evolving national threat, with new challenges emerging and spreading annually. At least three glyphosate-resistant species on the horizon for Pennsylvania require new strategies to combat them, according to a specialist in Penn State’s College of Agricultural Sciences.
Penn State Extension weed scientist Dwight Lingenfelter said several resistant species currently are approaching Pennsylvania. These weeds were controlled routinely over the years with glyphosate-based herbicide programs, but now the effectiveness of those programs is dwindling.
“There’s a species called Palmer pigweed or Palmer amaranth, which is a huge problem — especially in cotton-growing regions,” he said. “In the past, farmers were spending only maybe $20 to $30 an acre to control pigweed; now they’re up over $90 to $100 an acre, because of its resistance to a number of herbicide modes of action.
“Currently, we don’t have any major outbreaks of it in Pennsylvania, but we’re hearing reports from Delaware and Maryland that they’re starting to find Palmer pigweed, and it’s more than likely to creep into our cropping systems, especially in the southern tier of the state.”
Lingenfelter said a second resistant species slowly invading the state, water-hemp, already is creating big problems in the Midwest and South and is resistant to numerous herbicides as well.
“We had a person bring in a sample of water-hemp this summer, so we know there are some populations in our state currently,” he said. “We’re also seeing glyphosate-resistant species of horseweed or marestail spreading throughout the state — it’s very common in the mid-Atlantic region and Midwestern states.”
While it might sound like it’s losing its effectiveness, glyphosate is still vital in “burn-down” weed-control programs, which work by killing any vegetation on a treated field.
“It’s still a very effective herbicide for a number of species in our area,” he said. “It controls a number of weeds in the burn-down period and still is a foundation or backbone for many weed-control programs. We recommend using other herbicides in combination with it to control weeds that aren’t being controlled by glyphosate alone.
“We work with farmers to explain various programs that use different techniques and management options in a situation like that,” he said. “Generally, we recommend that if you’re using glyphosate in the burn-down, you also should use something such as 2-4-D or a product like Valor XLT Sharpen prior to planting soybeans. We also encourage tank-mixing herbicides or using pre-packaged products so multiple modes of action are in the weed-control program.”
The mode of action is the way an herbicide affects the weed to kill it, Lingenfelter explained. “There are about 10 different major modes of action available, and you can combine those to get control of the particular species you’re going after. We highly recommend having at least two modes of action that act on that particular weed species.”
Newer herbicide products introduced in the last five years can help control resistant species in burn-down programs. But Lingenfelter pointed out that, while “new” products are being introduced on the market, the industry hasn’t produced a formulation that employs a new mode of action in more than 15 years.
“The reality is that many companies are repackaging products and giving them different trade names so it looks like we have a lot of new herbicides when in reality we do not. And if they were to discover a new mode of action in some lab today, we wouldn’t reap the benefits of it for at least 10 years, because it takes that long to get through all of the testing phases and field trials before it would hit the market.”
Lingenfelter said the diversity and rotation of crops grown in Pennsylvania gives it an advantage over states in the Midwest and South when it comes to fighting resistant weeds. Corn, cotton and soybeans are the primary field crops in the Midwest and South, and more than 90 percent of the acres are sprayed with glyphosate, so weeds are pushed to develop resistance.
“Here in Pennsylvania, we typically rotate between corn, soybeans, alfalfa, small grains and sometimes various vegetable crops, depending on the area of the state,” he said. “Because of this, we use a variety of weed-control methods. Not only does this allow for different herbicides and a rotation of herbicide modes of action, but it allows for other weed-management techniques — such as mowing forage crops or the addition of cover crops — and other cultural tactics such as variations in planting date, seeding rate or row spacing.
“We still use a lot of Round-Up-ready corn and soybeans, but glyphosate is not the primary means of control. Also, different types of weeds are common in different crops depending on life cycles and growth habit. Our diverse rotations should hold off resistance pretty well, but we’ll have to start thinking about different techniques to handle it.”
Lingenfelter said Pennsylvania growers can learn a lesson from watching the experience of their neighbors in states to the south and west. “The majority of the resistance problem in these other regions is they were relying on a single mode of action — that being glyphosate.”
For more information, contact Dwight Lingenfelter at 814-865-2242 or dxl18@psu.edu.
Penn State scientists part of new stink bug research project
live.psu.edu/story/56032#nw69
October 27, 2011
Stink-bug damage such as this cost the mid-Atlantic apple industry an estimated $37 million in 2010. (Credit: Penn State Department of Entomology)
UNIVERSITY PARK, Pa. — Researchers in Penn State’s College of Agricultural Sciences are part of a new, multi-state project to study the brown marmorated stink bug.
The research is funded by a recently announced $5.7 million grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture through its Specialty Crops Research Initiative.
The three-year project is aimed at developing economically and environmentally sustainable pest-management practices for the brown marmorated stink bug, which has caused millions of dollars worth of crop damage and become a major homeowner nuisance since it first was found in the United States, near Allentown, in the late 1990s.
Penn State will receive nearly $900,000 of the grant to study stink bug biology and behavior, develop monitoring and management tools and practices, and provide extension education programs to disseminate new knowledge to crop producers.
“It’s too early to put a dollar value on crop damage this year, but the apple industry alone estimated losses of about $37 million as the result of stink bug infestations in the mid-Atlantic region in 2010,” said Greg Krawczyk, extension tree-fruit entomologist at Penn State’s Fruit Research and Extension Center in Biglerville.
Krawczyk, who leads the Penn State portion of the project, noted that crop damage this year appears to be lower than last year, though it varies from region to region. “Growers who experienced big losses last year managed this pest better during this season, but some individual growers still suffered losses of up to 60 percent,” he said.
Because the brown marmorated stink bug is native to Asia, it has few natural enemies in North America, allowing populations to grow largely unchecked. The pest is known to feed on as many as 300 host plants and migrates readily, further complicating control.
Krawczyk said one of the goals of the research is to develop control tactics that rely on the principles of IPM, or integrated pest management. IPM utilizes a variety of methods — including biological controls, pheromones for mating disruption and other techniques — that help minimize pesticide use.
He explained that some broad-spectrum pesticides that are effective against stink bugs also kill the beneficial insects tree-fruit growers rely on as part of IPM programs. “That upsets the balance in the orchard ecosystem — allowing other pests to become more of a problem — and could reverse much of the progress we’ve made in IPM, which has helped Pennsylvania growers to reduce pesticide use by as much as 75 percent in recent decades.”
Penn State scientists will study stink bugs as they relate to the production of tree fruits, vegetables and grapes. Researchers will explore biological control options, stink-bug chemical ecology (chemically mediated interactions among plants and insects), and monitoring strategies. The project also will assess the pest’s economic impact and the economic feasibility of new management methods.
Krawczyk said although the research will focus mostly on specialty crops and will not directly address infestations in homes or in major agronomic crops such as corn and soybean, knowledge gained should aid in the development of recommendations that could be useful for habitat-scale management.
Other Penn State personnel taking part in the project include David Biddinger, senior research associate in entomology at the Fruit Research and Extension Center; Gary Felton, professor and head of entomology; Shelby Fleischer, professor of entomology; Jayson Harper, professor of agricultural economics; Steven Jacobs, senior extension associate in entomology; Michael Saunders, professor of entomology; and John Tooker, assistant professor of entomology.
The project is led by USDA’s Agricultural Research Service, along with a core group of land-grant universities: Penn State, Rutgers, Virginia Tech, and the universities of Maryland and Delaware. Also participating are researchers from Cornell, Oregon State University, North Carolina State University, Washington State University and the Northeast IPM Center.
More information about the brown marmorated stink bug is available online at http://ento.psu.edu/extension/factsheets/brown-marmorated-stink-bug.
Weed Killers and Your Garden
http://www.emagazine.com/view/?5244
EARTHTALK
Week of 07/11/10
Dear EarthTalk: Within my lawn I have over 100 citrus, mango and avocado trees. When I use Scott’s Bonus S Weed and Feed, am I feeding my new fruit any poison? Will the weed killer be taken up by the fruit?– Richard Weissman, Miami, FL
In short, yes and yes: You will jeopardize the health of your fruit trees and your yard in general if you use such products. Scott’s Bonus S Weed and Feed, as well as many other “weed-and-feed” fertilizers (Vigero, Sam’s, etc.), contain the harsh chemical herbicide atrazine, which excels at terminating fast-growing weeds like dandelions and crabgrass but can also kill other desirable plants and trees and damage your entire yard as toxin-carrying root systems stretch underground in every corner and beyond.
Howard Garrett, a landscape architect who founded the DirtDoctor.com website and is an evangelist for natural organic gardening and landscaping, points out that anyone who reads the label on such products will learn that even manufacturers don’t take their health and environmental effects lightly. Some of the warnings right there in black and white on the Scott’s Bonus S Weed and Feed packaging include precautions against using it “under trees, shrubs, bedding plants or garden plants” or in the general vicinity of any such plants’ branch spreads or root zones.
Scott’s also recommends not applying it by hand or with hand-held rotary devices or applying “in a way that will contact any person either directly or through drift.” And just in case you were thinking it was okay for the environment, Scott’s adds that “runoff and drift from treated areas may be hazardous to aquatic organisms in neighboring areas” and that the product is “toxic to aquatic invertebrates.”
Of course, homeowners aren’t the only ones who want lush plant or grass growth without weeds. Farmers have been using atrazine for decades all over the country, although not surprisingly concentrations are highest along the Midwest’s so-called Corn Belt. The herbicide consistently delivers slightly increased agricultural yields, but environmentalists wonder at what cost. The Natural Resources Defense Council (NRDC), a leading environmental research and advocacy non-profit, reports that atrazine exposure has been shown to impair the reproductive systems of amphibians and mammals, and has been linked to cancer in both laboratory animals and humans. Male frogs exposed to minute doses of the herbicide can develop female sex characteristics, including hermaphroditism and the presence of eggs in the testes. Researchers believe such effects are amplified when atrazine and other chemicals are used together.
As to safer alternatives, Garrett recommends organic fertilizers. “Synthetic fertilizers are unbalanced, often contain contaminants, have no carbon energy, contain far too much nitrogen and have few trace minerals,” he says. “Organic fertilizers, on the other hand, contain naturally buffered blends of major nutrients, trace minerals, organic matter and carbon. They have lots of beneficial life and, most important, they contain nothing that will damage the roots of your trees and other plants.” Some of Garret’s top choices include corn gluten meal (a natural way to prevent the growth of new weeds), THRIVE by AlphaBio, Garrett Juice, Ladybug, Medina, and Soil Mender. More and more choices are coming on the market all the time thanks to the growing popularity of organic gardening.
CONTACTS: Scotts; The Dirt Doctor; NRDC.
Research links pesticides with ADHD in children
May 17, 12:02 AM EDT
Research links pesticides with ADHD in children
By CARLA K. JOHNSON
AP Medical Writer
CHICAGO (AP) — A new analysis of U.S. health data links children’s attention-deficit disorder with exposure to common pesticides used on fruits and vegetables.
While the study couldn’t prove that pesticides used in agriculture contribute to childhood learning problems, experts said the research is persuasive.
“I would take it quite seriously,” said Virginia Rauh of Columbia University, who has studied prenatal exposure to pesticides and wasn’t involved in the new study.
More research will be needed to confirm the tie, she said.
Children may be especially prone to the health risks of pesticides because they’re still growing and they may consume more pesticide residue than adults relative to their body weight.
In the body, pesticides break down into compounds that can be measured in urine. Almost universally, the study found detectable levels: The compounds turned up in the urine of 94 percent of the children.
The kids with higher levels had increased chances of having ADHD, attention-deficit hyperactivity disorder, a common problem that causes students to have trouble in school. The findings were published Monday in Pediatrics.
The children may have eaten food treated with pesticides, breathed it in the air or swallowed it in their drinking water. The study didn’t determine how they were exposed. Experts said it’s likely children who don’t live near farms are exposed through what they eat.
“Exposure is practically ubiquitous. We’re all exposed,” said lead author Maryse Bouchard of the University of Montreal.
She said people can limit their exposure by eating organic produce. Frozen blueberries, strawberries and celery had more pesticide residue than other foods in one government report.
A 2008 Emory University study found that in children who switched to organically grown fruits and vegetables, urine levels of pesticide compounds dropped to undetectable or close to undetectable levels.
Because of known dangers of pesticides in humans, the U.S. Environmental Protection Agency limits how much residue can stay on food. But the new study shows it’s possible even tiny, allowable amounts of pesticide may affect brain chemistry, Rauh said.
The exact causes behind the children’s reported ADHD though are unclear. Any number of factors could have caused the symptoms and the link with pesticides could be by chance.
The new findings are based on one-time urine samples in 1,139 children and interviews with their parents to determine which children had ADHD. The children, ages 8 to 15, took part in a government health survey in 2000-2004.
As reported by their parents, about 150 children in the study either showed the severe inattention, hyperactivity and impulsivity characteristic of ADHD, or were taking drugs to treat it.
The study dealt with one common type of pesticide called organophosphates. Levels of six pesticide compounds were measured. For the most frequent compound detected, 20 percent of the children with above-average levels had ADHD. In children with no detectable amount in their urine, 10 percent had ADHD.
“This is a well conducted study,” said Dr. Lynn Goldman of the Johns Hopkins Bloomberg School of Public Health and a former EPA administrator.
Relying on one urine sample for each child, instead of multiple samples over time, wasn’t ideal, Goldman said.
The study provides more evidence that the government should encourage farmers to switch to organic methods, said Margaret Reeves, senior scientist with the Pesticide Action Network, an advocacy group that’s been working to end the use of many pesticides.
“It’s unpardonable to allow this exposure to continue,” Reeves said.
On the Net:
Pediatrics: http://www.aap.org/
EPA: http://www.epa.gov/pesticides/food
U.S. Farmers Cope With Roundup-Resistant Weeds
http://www.nytimes.com/2010/05/04/business/energy-environment/04weed.html