To see this report in Portable Document
Format (PDF), please click on the button. 
Should you not have Adobe
Acrobat Reader (required to read PDF files), this free program
is available for download at http://www.adobe.com/prodindex/acrobat/readstep.html
Open Forum: In an attempt to promote free and open discussion of issues, The Agrichemical and Environmental News encourages letters and articles with differing views. To discuss submission of an article, please contact Dr. Allan Felsot at 509-372-7365 or afelsot@tricity.wsu.edu or Dr. Catherine Daniels at 509-372-7495 or cdaniels@tricity.wsu.edu. The newsletter is available in a hardcopy version for a $15 yearly subscription fee. Please contact newsletter editor Sally O'Neal Coates at 509-372-7378 or scoates@tricity.wsu.edu for details.
Return to Agrichemical and Environmental News Index
Transgenic crops have been good for publishers of both print and internet media. Websites have proliferated touting the various "truths" about genetically modified crops, ranging the gamut from safety and benefits to lurking catastrophe. Printed books proclaim fearful postures with titles like Against the Grain: Biotechnology and the Corporate Takeover of Your Food (5) and Genetically Engineered Food: Changing the Nature of Nature (subtitled What You Need to Know to Protect Yourself, Your Family, and Our Planet) (14). Forwards penned by crusaders like Ralph Nader destine these books for the best-seller list. But should the man who told us not to buy the rear engine-mounted Corvair be trusted about the dangers of biotechnology?
Therein lies a big problem. Who and what information do we trust to decide whether transgenic technology is safe? The books mentioned above (which were actually copyrighted by environmental advocacy groups), as well as the Greenpeace website (4) are obviously against genetic engineering of food. But they do raise the following legitimate concerns about the short- and long-term safety of transgenic crops:
Greenpeace et al. argue that these concerns were not addressed prior to commercializing and planting millions of acres of transgenic crops, or, as the Europeans call them, GMOs (genetically modified organisms). But based on the acreage of Bt transgenic corn and cotton planted in the United States (Figure 1), we and our livestock have already been exposed to transgenic crops for at least four years, apparently without any health problems. Are we all just guinea pigs? Or has the safety information been available all along, but not accessed by those concerned?
Use of Bt transgenic corn and cotton in the U.S. |
 |
I can understand why many feel uncomfortable with GMOs. The study of genetics in high school biology classes was not a particularly pleasant experience. If you haven't followed the transformation of high school genetics into college biology and beyond to molecular biology, then transgenic technology will seem simultaneously new, mira-culous, and overwhelmingly mysterious. The arcane jargon of molecular biologists makes their tricks of trade inaccessible to all but ardent practitioners. Thus, genetic engineering seems remote and untested. Yet for over twenty-five years we have had the capability to move genes from one species to another. Such feats grew in parallel with our understanding of how to map gene locations on the chromosomes.
Nevertheless, the concerns posed by environmental advocacy groups are legitimate. To address the validity of these concerns, we must separate what is testable and what is sociological. In this essay I address the question of whether Bt proteins can be toxic to humans and whether they can pose risks of allergic reactions.
Bt transgenic crops are considered "plant pesticides," and they are subjected to the same battery of tests given to old and new chemical pesticides. Perhaps on the surface, it looks as though the U.S. Environmental Protection Agency (EPA) gave the major transgenics producers the green light to commercialize their seed lines with just a cursory critique. But, in fact, the risk assessment process was expedited by the nearly forty years of positive experiences with commercial Bt sprays.
The place to start with questions about the safety of Bt transgenic crops is with Bt itself. Bt is one of many microbial pesticides. Its formulated fermentation cultures can be sprayed on foliage to control selected insects because the ubiquitous bacterium synthesizes a toxic protein, known as the delta-endotoxin, every time it stops growing and produces a spore. In 1998, the EPA compiled many years of collected data into a re-registration eligibility decision document (RED) that covers all Bt products not produced by genetic engineering (17). The data overwhelmingly supported the safety of Bt to humans and nontarget organisms. Certain Bt spray formulations are among the few insecticides certified for organic agriculture (19).
Over twenty years ago, scientists began to discover numerous strains of Bt that were toxic to different spectra of insects. More than fifteen years ago, molecular biologists began to identify the genes coding for the various insecticidal proteins characteristic of the individual Bt strains. Eventually they successfully moved these genes across species lines and into production crops.
The insecticidal gene the molecular biologists moved into corn, cotton, or potatoes is actually a truncated version of the natural gene. For the gene to function in plant cells, small snippets of DNA are attached that allow the code to be read. To track the location of the gene and help select plant cells that have successfully incorporated the gene into their chromosome, marker genes encoding for either antibiotic or herbicide resistance are also spliced onto the toxic protein gene. The plant cells, however, do not activate the antibiotic markers. The herbicide resistance gene specifically confers protection to a naturally occurring bacterial amino acid called phosphinothricin, which is the active ingredient of the commercial herbicide glufosinate.
We have known for a long time that the insecticidal proteins produced by the various strains of Bt are toxic only to comparatively few species of insects by virtue of the coincidence of the insects specialized gut physiology and shape of the proteins themselves. All other organisms, lacking these unique factors, tolerate Bt exposure without exhibiting symptoms of injury. Indeed, high doses of Bt that are fed, injected, or placed in the air of laboratory rats are essentially non-toxic. Similarly, feeding rats high doses of any of the purified insecticidal proteins causes no measurable toxic effects (Table 1). For comparison, the table shows how common substances around the house (table salt, caffeine, vitamin A, and the lawn herbicide 2,4-D) could cause illness at much lower doses than Bt proteins.
|
|||
|
|||
Registered Transgene |
|
|
|
| Bt CryIA(b) |
|
|
|
| Bt CryIA(b) |
|
|
|
| Bt CryIA(c) |
|
|
|
| Bt Cry9C |
|
|
|
| Bt spray |
|
|
|
| Table Salt |
|
||
| Caffeine |
|
||
| Vitamin A |
|
||
| 2,4-D |
|
||
B) LD50 for oral exposure of rats C) Level of exposure causing adverse effects |
|||
Controversy surrounds the potential for non-protein chemicals to cause adverse effects after long-term (i.e., chronic) daily exposure. However, when proteins are toxic, the effect is immediate (acute), never cumulative (chronic) (11).
Despite the good news shown in Table 1, it might be argued that Bt sprays do not leave as much insecticidal protein as is present in a transgenic plant, in which every tissue makes large quantities of the protein. Dose makes the poison, so how do we know that we just haven't fed the rats enough protein to cause an effect? To answer this question, we need to know how much protein we might be exposed to if eating food made from transgenic corn.
Fortunately, the amounts of Bt protein in various tissues of transgenic corn plants throughout the growing season have been measured and reported to the EPA (16).
The levels of Bt protein in currently registered transgenic corn hybrids range from non-detectable quantities (<0.005 micrograms per gram of plant tissue, µg/g) to 4 µg/g. (Table 2. Note that, contrary to popular perception, different tissues do not express the same amount of protein. For these calculations we are referring to the edible component, the grain.) Using the highest amount of protein present in grain, we can calculate the amount of popcorn needed to be consumed by a human two-year-old child to reach the highest doses fed to rats. To reach a human-equivalent dose of 5000 milligrams of Bt protein per kilogram of rat body weight (mg/kg), a child would have to eat 27.5 pounds of popcorn. Assuming every new video release is equivalent to one pound of popcorn, even a movie critic can't see that many movies in a day. In other words, the EPA justifiably declared the risk of a toxic reaction from Bt proteins as essentially nil.
|
||||||
|
||||||
Registered Transgene |
Whole Plant |
Leaf |
Roots |
Pollen |
Grain |
Grams of insecticidal protein per acre |
| Bt CryIA(b) | 3.65-4.65 | 7.93-10.34 | NA | 0.09 | 0.18-0.39 | 16.4-20.9 |
| Bt CryIA(b) | 0.6 | 4.4 | <0.008 (A) | 7.1 | <0.005 (A) | 2.7 |
| Bt CryIA(c) (B) | 0.22 | 0.10 - 0.26 | 0.03 | NA | 0.01 | 1.5 |
| Bt Cry9C (B) | 4.7 | 9.5 | 5.6 | 0.1 | 4 | 21.3 |
| Bt spray (C) | NA (D) | NA | NA | NA | NA | 14 |
(A) Limit of detection
for the Novartis transgene protein was roots, 0.008 µg
protein per gram tissue and grain, 0.005 µg/g
|
||||||
I found a very scary website the other day published by a group called STOP (Society Targeting Overuse of Pesticides) (13). In a four part "exposé" they used a combination of physician anecdotes, testimonials, and out-of-context statements from toxicology studies to paint a very alarming picture of Bt sprays, despite overwhelming evidence of the safe use of Bt sprays for over forty years (remember--it's certified organic). STOP does, however, raise an important issue of whether some individuals are uniquely sensitive. Allergic reactions to proteins are not uncommon, but allergy has a well-defined etiology (i.e., biochemical cause) that is quite distinct from toxicity .
It is clear from my interpretation of the STOP anecdotes, that reports of illness following woodland sprayings of Bt products have not been clinically confirmed as toxicity, but could conceivably enter the realm of allergic reaction. (It is important to note that, because Bt sprays are formulated with other non-insecticidal ingredients [officially known as inerts] to ease their delivery, adverse reactions are not necessarily a result of the Bt protein itself.)
A number of food proteins are definitively associated with allergenic reactions. Fortunately, we know quite a bit about the biochemical events associated with allergic reactions, as well as the kinds of proteins that cause problems (6). First, an allergic response should be distinguished from toxicity. Toxicity is the cascade of reactions resulting from exposure to a dose of chemical sufficient to cause direct cellular or tissue injury or otherwise inhibit normal physiological processes. Allergic responses are immune system reactions resulting from stimulation of a specific group of antibodies known as IgE.
Many food allergens are proteins that are fairly stable to digestion or only partially broken down (6). The protein or its fragments migrate across the intestinal wall and stimulate immune cells known as lymphoctyes. Lymphocytes stimulate the production of the IgE antibodies that are specific for each allergen (which is also known as an antigen). Eventually, subsequent exposures to the antigens lead to release of biochemicals known as histamines and prostaglandins. These chemicals, in an effort to protect the body, cause smooth muscle contractions (for example, the gut walls), dilation of blood vessels, and constriction of the lung bronchia. Such effects manifest as the typical allergic symptoms of respiratory distress, running nose and stuffiness, swelling, and skin rashes.
One way to determine whether food proteins are allergenic is to determine their digestibility using mixtures that simulate the environment of the stomach with its acid pH and enzymes. If a protein is unstable in this environment after a short contact time, then it has no potential for allergenicity. Food allergens are almost always proteins, and one common characteristic among them is their stability to digestion, as well as to heat (as in cooking) (6). Furthermore, the amino acid sequence of allergenic food proteins have been mapped out, and suspected allergens can be compared for similarities in structure. Finally, many protein allergens have a sugar molecule attached to them while they are partially transformed in a reaction known as glycosylation.
With the exception of the cry9C-containing hybrid of corn, all transgenic Bt proteins are rapidly degraded by the stomach environment and are unstable when heated (Table 1). The cry9C protein is stable to simulated stomach conditions, but it is not glyco-sylated and has not caused any adverse effects characteristic of immune system responses in mammalian studies. Furthermore, no part of its structure resembles known allergenic proteins.
A recently published study showed that farm workers who picked vegetables that were sprayed with a commercial Bt formulation called Javelin exhibited positive responses to skin prick and antibody tests (2). The Bt formulation is a fairly complex mixture containing large amounts of spores, intact delta-endotoxin proteins, residual amounts of fermentation medium, bacterial cell wall debris, and vegetative (i.e., growing) Bt cells.
The experimenters prepared the Javelin in
the laboratory to separate water soluble components, the Bt spores,
and the Bt endotoxin protein. They then subjected the farm workers
to skin prick tests, which are routinely used to test for allergic
reactions to foods or other substances. Only the Javelin extracts
representing the water soluble portions and the spores gave positive
reactions. No significant positive reactions were noted with the
delta endotoxin proteins. Test-tube-type studies with the IgE
antibody confirmed that only the water soluble extracts and spores
gave positive immune system reactions.
The unique experimental design of the farm worker study allowed
the authors to confidently conclude, "results of this investigation
should partially allay recent concerns about the occurrence of
possible adverse health effects in consumers after exposure to
transgenic foods." Furthermore, "it is unlikely that
consumers would develop allergic sensitivity after oral exposure
to transgenic foods (e.g., tomatoes, potatoes) that currently
contain the gene encoding this [the Bt] protein."
As the number of acres farmed by certified organic practices increases along with the acreage of Bt transgenic crops, no doubt we will be exposed to Bt protein. But transgenics or not, we already are exposed to Bt proteins. Indeed, our exposure may be ancient as well as unavoidable. Studies of the natural ecology of Bt show it is abundant in the foliage of numerous plant species, and its presence in the soil may result from washoff with rainfall (7, 12). Even more curious is the occurrence of Bt in stored grain that has not been specifically sprayed. Stored grain is commonly infested by moths and beetles that may be susceptible to naturally occurring Bt. Exposure to Bt by organisms feeding on the grain is confirmed by finding Bt spores in the feces of birds and rodents collected from the feed mill (8). Indeed, birds and rodents have been suggested as possible spreaders of the Bt spores. A recent study from Canada indicated that Bt can be detected occasionally on produce in grocery stores when no known aerial applications have taken place on the subject crops in the field (3).
Still, some people will be concerned about the ubiquity of the Bt transgenic protein in whole fields of corn or cotton. But would the amount necessarily be any different than produced by applications of Bt spray? The mass of Bt endotoxin protein in a corn crop after spraying one commercial product may approach 14 grams per acre. The amount of protein in transgenic crops could be as low as 1.5 grams per acre or as high as 21 grams per acre (Table 2). Thus, the introduction of engineered protein into the environment doesn't seem to present an environmental burden any different than a single Bt spray.
One argument that Greenpeace uses to warn us against transgenic foods is that the genes being transferred come from sources that have never been part of the human diet. The ubiquity of Bt in the environment, and its presence on fresh unsprayed produce and in stored grain suggests that we have historically been exposed to Bt proteins.
Greenpeace warns us by relating the story of allergenic soybeans produced after being engineered with a gene from Brazil nuts that directed increased synthesis of the essential amino acid methionine (10). But they do not emphasize that the researchers already knew that Brazil nuts contained an allergenic protein. Indeed, the purpose of the study was to determine whether transfer of the Brazil nut gene to soybean would express a protein possessing the same allergenic property. The researchers did not uncover anything unexpected but proved that transgenes from allergenic foods are still functional. FDA policy already mandates labeling of foods with genes from known allergenic foods (9).
I'm sure that Greenpeace staff bet that few internet surfers will seek out and read the original scientific studies they mention to validate their position. But they shouldn't be surprised that contrary perspectives abound among those who critically read the scientific literature.
A perception exists that our regulatory system is broken and the EPA cannot be trusted. Take it from a rabid critic of EPA's risk assessments that prior to registering Bt transgenic crops, the agency already had in hand all of the studies addressing the health issues raised by Greenpeace and others. In Part III, I'll examine the remaining issues concerning environmental effects and resistance management.
Dr. Allan S. Felsot is an Environmental Toxicologist with the Food and Environmental Quality Lab at Washington State University, and a frequent contributor to AENews. He can be reached at (509) 372-7365 or afelsot@tricity.wsu.edu.
Think of insects and mites in an agricultural context and you will think of pests-the (usually) small organisms that chew or suck the life out of crops, reducing quality and profits. But not all insects and mites are our enemies. Some bugs are most definitely our friends and we are increasingly recruiting them as valuable foot soldiers in our battles against their pestiferous cousins.
As this new century begins, the focus of crop pest management around the world has shifted, and will continue to shift, towards reducing pesticide inputs. Already we have made great advances in this direction but the greatest advances are likely yet to come. Integrated Pest Management (IPM) has become the catch cry of pest control specialists everywhere. Biological control is usually a part of IPM systems. This is where our foot soldier bugs come in.
Biological control of insect and mite pests is most often thought of in "classical" terms. Classical biological control involves importing an exotic predator or parasitoid to control an exotic pest. This is the kind of biological control that receives media attention. The first and possibly most famous classical biological control success involved the Australian cottony cushion scale insect, which threatened to destroy the Californian citrus industry early last century. Importation of an Aussie beetle predator by American entomologists saved the day (and the industry).
However, most biological control is truly natural. It occurs without fanfare, often unobserved or unrecognized. This type of biological control is referred to as "conservation biological control." The existence of a successful biological control system of this type sometimes is recognized only when something disrupts it. Using a broad-spectrum insecticide (i.e., one that kills ALL insects and mites, good and bad, in a crop) is often a good way of disrupting, thereby exposing, a natural biological control system. For example, spider mites in many crops only become significant pests when their predators are killed. Large populations of spider mites are rarely found in natural or relatively undisturbed ecosystems like woodlands or parks.
Preserving and encouraging beneficial insect and mite populations in agroecosystems is a fundamental component of IPM. To do so, we need to know which pesticides the beneficials can tolerate and which they cannot. Armed with this information, we can develop IPM programs that are highly compatible with those insects and mites most beneficial to a particular crop.
At present, very little information on tolerance to specific pesticides is available for our beneficial bugs in Washington State. A new research program has been established at Washington State University Prosser to fill this information void, at least for the approximately twenty-five important beneficial bug species found in grapes and hops. Using laboratory bioassay techniques and procedures, researchers will examine each species of beneficial insect and mite for susceptibility to a range of commonly used pesticides (i.e., insecticides, miticides, fungicides). First, we will determine the toxicity of different pesticides to predators and parasitoids. We will also examine possible sub-lethal impacts of pesticides (such as suppression of reproduction) on beneficials. We will consider the possibility of positive effects of pesticides on beneficials as well. For example, a commonly used insecticide in Washington, imidacloprid (trade names: Admire, Provado) has been demonstrated to increase reproduction in one species of predatory mite (James 1997).
Fungicides, the impact of which is often ignored, can also affect beneficial bugs, particularly predatory mites. For example, the use of lime sulfur and mancozeb for disease control was once a major impediment to biological mite control in Australian vineyards. Substitution of fungicides determined to be safe to predatory mites, such as wettable sulfur, copper, and some synthetics, resulted in commercially acceptable biological control of mites (James 1989, James and Whitney 1993, James and Rayner 1995). Perhaps research on predatory mites in Washington vineyards could result in a similar positive outcome.
Clearly, examining the individual susceptibilities of natural enemy species to different pesticides is an ambitious program. However, it is one that is crucial to the effective development of IPM systems in hops and grapes. We must learn more about the impacts of all chemicals used in crops, on the good bugs as well as the bad bugs. Armed with this information, we will be able to more effectively recruit and utilize our insect and mite friends as allies in the ongoing war against crop pests.
Dr. David James is an Assistant Entomologist with Washington State University's Irrigated Agriculture Research and Extension Center (IAREC) in Prosser. He can be reached at djames@tricity.wsu.edu or (509) 786-9280.
In the "chemical soup"
of the environment, insects must locate food and shelter, avoid
being eaten, and-for obvious reasons-boy must meet girl. For many
lepidopterans (moths), success in finding a mate is achieved through
the female's release of attractant chemicals that prove irresistible
to males of her species. These attractant chemicals are known
to science as "sex pheromones." The sex pheromone for
a female moth must be able to rise out from the "background
stink" of competing odors and convey the unambiguous message
to males of her species, "I am here and I am ready for sex."
A female moth excretes pheromones in the form of an odor cloud or "plume" that travels through the air carrying its seductive message as it evaporates and dissipates. Typically, she will only produce and release pheromones at certain times of the day under specific environmental conditions. Release of pheromones during windy or rainy weather, for example, would prove unproductive. The shape and effective dispersal of the plume in the airstream is determined by factors including wind, temperature, vapor pressure, and topography.
Pheromone structures must remain fairly stable as they move through the air. Large molecules can prove unstable and too heavy to volatilize, while small ones can dissipate too rapidly. In keeping with this objective, moth sex pheromones have a very limited size range, containing between twelve and twenty carbons (see examples, Figure 1).
We know a great deal about the chemistry of sex pheromones. They are metabolically derived from fatty acids. Codling moth pheromone's main component is (E,E)-8,10-dodecadien-1-ol, a primary alcohol consisting of a straight chain of twelve carbons with two conjugated double bonds. Other moth pheromones contain molecules that differ substantially in structure; some are epoxides, acetates, or aldehydes (Figure 1). The codling moth pheromone, also known as codlemone, is an excellent example of a successfully synthesized pheromone with commercial application in mating disruption (see AENews Issue 159, "Codling Moth: Serious Pest Provides IPM Model.")
One might think that the female moths' limited range between twelve and twenty carbons for their pheromone structures would result in interspecific sensitivity among the thousands of moth species that release pheromones-i.e., moths of various species being attracted to one another's pheromones. In fact, pheromone chemists have determined that many pheromones consist of blends of two or more volatile chemicals that need to be emitted in exactly the right proportions to elicit the correct response from the appropriate male.
In addition to chemical structure differences between the various moth pheromones, there are substantial differences between species in the release rates and activity period of pheromones. For example, the codling moth pheromone evaporates about 7.5 times faster than that of the Pandemis leafroller (Figure 1).
The Nearness
of YouProximity is another factor in the success of pheromone attraction. While a moth pheromone plume can be huge, with detectable pheromones ranging from yards to miles from the point-source female, concentration of the attractant does decrease with distance from the female. To be effective, the sex pheromone must persist at a sufficient concentration when it reaches the recipient male moth to elicit a response.
In theory, the female silk moth produces sufficient attractant to excite ten trillion male moths. But environmental factors, release rate, and proximity must align if the excitation response is to occur.
Finding himself within the active space of a pheromone plume, the male moth's initial long-range orientation is though anemotaxis-movement into the prevailing wind. As he gets closer, the male may orient himself toward the female by chemotaxis-movement toward the higher concentration of pheromone.
Once the male is in close proximity to the female, and the pheromone concentration has exceeded a threshold, genetically stereotyped responses are set in motion. A cascade of behavioral courtship behaviors begins. If the female deems him worthy, copulation will occur.
Next month, I will address the biological aspects of sex pheromones. Male moths detect pheromones via neural structures on their antennae called sensilla. These structures result in a marked difference in appearance, or sexual dimorphism, between males and females in many moth species.
Dr. Douglas B. Walsh is an Agrichemical and Environmental Education Specialist with WSU's Food and Environmental Quality Laboratory. His office is at the Irrigated Agriculture Research & Extension Center (IAREC) in Prosser, and he can be reached at dwalsh@tricity.wsu.edu or (509) 786-2226.
|
 |
of selected moth pheromones. |
Return to Table of Contents for the April 2000 issue
In the February 1999 issue of Agrichemical and Environmental News, Washington State University's Pesticide Information Center (PIC) attempted to summarize the value of Section 18s to Washington agriculture. Using economic data from the Section 18 requests, we concluded that in 1998 alone, Section 18s were worth $443.2 million to Washington's agricultural industry. Dollar figures for Section 18s are typically comprised of avoided crop losses but may also include savings associated with not having to replant or rehabilitate acreage involved in severe pest infestations.
A year later, we find-not surprisingly-that Section 18s are still saving the industry money. The estimated dollar value of Section 18s issued in 1999 was $447.7 million, up $4.5 million from 1998.
While these numbers are interesting to compare and may even be impressive to toss around, be aware of some disclaimers:
Given those caveats, those of you who find this number useful or even interesting can track this information on an ongoing basis via WSU's Pesticide Notification Network web page. You can get there through the PICOL (Pesticide Information Center On-Line) web page or directly by going to the PNN page itself. Once on the PNN web page, click on the Section 18 information and pull up the list for 2000. As we receive each Section 18 request, we calculate and post the estimated value. When a Section 18 is issued as either an emergency exemption or a crisis exemption the value is then added to the annual running total at the top of the page.
What all this really means is that we should take a minute to thank the growers, commodity/commission groups, WSU research and extension staff, WSDA, and, yes, even EPA. The people who work processing Section 18s are making a significant contribution to Washington agriculture. And that's no estimate!
Jane M. Thomas is the Pesticide Notification
Network (PNN) Coordinator for the Pesticide Information Center
(PIC) at WSU. She can be reached at (509) 372-7493 or jmthomas@tricity.wsu.edu.
| *ED. NOTE: For the uninitiated, a "Section 18" is a temporary exemption of a pesticide from the full requirement of registration in the case of an emergency circumstance. This exemption derives its nickname from the section of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) that provides for it. (BACK TO ARTICLE) |
Return to Table of Contents for the April 2000 issue
Follow the links below to a series of tables summarizing a number of new pest control products introduced over the past several years. These lists were compiled from the Interregional Research Project #4 (IR-4) Winter 2000 newsletter. Further details on individual products can be found on the IR-4 website. Many of the pesticides listed exhibit reduced risk and may serve as viable alternatives for older pesticides. If you are interested in determining whether specific technologies could meet your crop protection needs, please contact me at (509) 786-2226 or dwalsh@tricity.wsu.edu.
|
|||||
|
|
|
|
|
|
Return to Table of Contents for the April 2000 issue
|
In contrast to the usually more sober contributors to the Agrichemical and Environmental News, Dear Aggie deals light-heartedly with the peculiarities that cross our paths and helps decipher the enigmatic and clarify the obscure. Questions may be e-mailed to Dear Aggie at dearaggy@tricity.wsu.edu. Opinions are Aggie's and do not reflect those of WSU.
Dear Aggie:
I ran across the following in the February 23, 2000, Federal Register:
"This regulation establishes time-limited tolerances for residues of the inert ingredient (herbicide safener) 3-dichloroacetyl-5-(2-furanyl)-2, dimethyloxazolidine, which is also known as furilazole (CAS Reg. No. 121776-33-8) in or on corn commodities (grain, forage, and stover), at 0.01 ppm."
If inert ingredients are so darned inert, why do they need tolerances?
Inert Inquirer
Dear Inquirer:
A truly "inert" ingredient may not need a tolerance, but it might have one anyway. The reason can be found in CFR 40 Ch. 1 §153.125 (e):
Designation of a substance as a pesticidally inert ingredient does not relieve the applicant or registrant of other requirements of FIFRA with respect to labeling of inert ingredients or submission of data, or from the requirements of the Federal Food, Drug, and Cosmetic Act with respect to tolerances or other clearance of ingredients. (emphasis added)
So, whether the registrant decided to apply for a tolerance or EPA decided to require one, the result will be an inert ingredient with an established tolerance.
That answers your direct question, but Aggie became fascinated by an additional, implied question: "When is an inert not inert?" or "Are safeners necessarily inert?" (If you weren't implying that, no matter. When Aggie becomes fascinated, it's "in for a penny, in for a pound.")
The crux of this matter is the definition of "inert," as opposed to "active." The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) clearly designates an ingredient "active" if it has direct pesticidal activity OR if it "has the ability to elicit or enhance" the pesticidal effect of another compound; in other words, if it's a "helper." A good example is that can of RAID® on your grocer's shelf. Check the label and you'll see a potent combination-an active pyrethrin insecticide and its (non-insecticidal, but technically "active") synergist, PBO (piperonyl butoxide).
Safeners are a special type of "helper" compound, acting to "safen" the activity of another compound so that the latter can be tolerated by a subject crop. For example, thiocarbamate and chloroacetamide herbicides are registered for use on corn and sorghum but are actually toxic to them. Safeners are added to the formulation to help these crops break down the toxic herbicide faster. (The safeners themselves may have direct herbicidal activity but only at very high doses.) It could be said that such safeners "elicit or enhance" the weed control effect of the primary compound. Interpreted thus, the law would consider safeners active ingredients, not inerts. In this light, your original question might have been whether the author of the Federal Register entry you cited was in error calling furilazole an "inert." Naturally, Aggie would not presume to make that accusation, and is relieved that was not the question you asked.
(Reference: Code of Federal Regulations 40, Subpart G, section 153.125, Criteria for determination of pesticidal activity; Devine et al. 1993, Physiology of Herbicide Action, PTR Prentice Hall)
Dear Aggie:
I heard the other day that the USDA has passed some rules regarding organic agriculture. Seems to me that I heard this about two years ago. Aggie, I'm getting the sense of déjà vu all over again. Am I losing my memory?
Been Here Before
Dear Been Here:
Aggie can't tell if you're losing your memory, but you have certainly heard this news story before. The USDA Agricultural Marketing Service released the first proposed rules for a national organic standard on December 16, 1997. The agency received 275,603 responses, an historical record. Nearly every response was adamantly against allowing, as the initial proposal did, the use of genetically engineered food, irradiation, and sewage sludge in organic agriculture and food processing. The second draft of the proposed rules eliminates these three bones of contention, with the interesting disclaimer by the USDA that there was no evidence of any adverse effects from any of the three practices. The recently released rules can still be commented upon, but USDA expects to have the final rule out by the end of the year. Who says the government doesn't reflect the will of the people? (http://www.ams.usda.gov/nop/)
Return to Table of Contents for the April 2000 issue
Washington Pest Consultants Association organizes an annual series of collection dates and sites for empty pesticide containers. Dates and locations are subject to change; it may be wise to confirm with a telephone call before participating. Contact telephone numbers for specific events are given in the table below. For general questions, or if you are interested in hosting an event at your farm, business, or in a central location in your area, contact Northwest Ag Plastics representative Clarke Brown at (509) 965-6809 or David Brown at (509) 469-2550 or dbrownwash@msn.com.
| Apr. 3 | 8a-11a | Bruce | Simplot | Chuck Spytex | (509) 488-2132 |
| 1p-3p | Othello | B&H Chemical | Larry Hawly | (509) 488-6576 | |
| Apr. 4 | 8a-Noon | Harrah | Husch & Husch | Allen Husch | (509) 848-2951 |
| Apr. 24 | 9a-11a | Quincy | Quincy Farm Chemical | Ron Turner | (509) 787-3556 |
| May 1 | 8a-Noon | Walla Walla | McGregor's | Gary Burt | (509) 529-6787 |
| 1p-3p | Waitsburg | McGregor's | Terry Jacoy | (509) 337-6621 | |
| May 2 | 8a-11a | Pomeroy | Western Farm Service | Jerry Wilsey | (509) 843-3491 |
| 1p-3p | Dayton | McGregor's | Jeff Bruce | (509) 397-4704 | |
| May 3 | 8a-10a | Prescott | Agri Northwest | Shawn Elder | (509) 547-8870 |
| 11a-2p | Prescott | Broetje's Orchard | Joe Shelton | (509) 749-2217 | |
| Prescott | Flat Top Ranch | Dave Hovde | (509) 547-9682 | ||
| 3p-5p | Pasco | Air Trac | Gerald Titus | (509) 547-5301 | |
| May 4 | 8a-11a | Eltopia | Wilbur Ellis | Vern Record | (509) 297-4291 |
| 1p-3p | Eltopia | Eastern Wa Spray Serv. | Willis Maxon | (509) 297-4387 | |
| May 5 | 8a-Noon | Connell | B&R Crop Care | Chris Eskildsen | (509) 234-7791 |
| 1p-3p | Pasco | Pfister Crop Care | Steve Pfister | (509) 297-4304 | |
| May 8 | 1p-3p | Seattle | Washington Tree Svc. | Ron Angel | (360) 362-9100 |
| May 9 | 8a-Noon | Mount Vernon | Skagit Public Works | Robin LaRue | (360) 336-9400 |
| 1p-3p | Mount Vernon | Tronsdale Air Service | Kevin Belisle | (360) 661-0422 | |
| May 10 | 8a-11a | Port Orchard | Kitsap Mod. Risk Facility | Niels Nicolaisen | (360) 337-5781 |
| Olympic View Ind. Pk | Omega Pest Management | Todd Best | (360) 373-4531 | ||
| 1p-4p | Tacoma | DOT/Wilbur-Ellis Co. | Randy Knutsen | (253) 351-6591 | |
| DOT Permit Office | Dave Patterson | (253) 589-7255 | |||
| May 11 | 8a-Noon | Puyallup | Pete's Spray Service | Pete Tovoli | (253) 922-9437 |
| May 12 | 8a-Noon | Centralia | Lewis Cty Public Works | John Prigmore | (360) 740-1193 |
| 2p-4p | Morton | DOT | Craig Robbins | (360) 496-5516 | |
| May 16 | 8a-10a | Fairfield | Wilbur Ellis | Ric Murison | (509) 283-2411 |
| 11a-1p | Waverly | Wilbur Ellis | Monte Bareither | (509) 283-2432 | |
| 3p-5p | Tekoa | McGregor's | Charles Wedin | (509) 284-5391 | |
| May 17 | 8a-10a | Oakesdale | Wilbur Ellis | Jerry Jeske | (509) 285-4511 |
| 11a-1p | Garfield | Cascade Flying Service | Doran Rogers | (509) 635-1212 | |
| 3p-5p | Palouse | McGregor's | Dale Deerkop | (509) 635-1591 | |
| May 18 | 8a-11a | Pullman | McGregor's | Larry Schlenker | (509) 332-2551 |
| 1p-3p | Mockonema | McGregor's | Dale Deerkop | (509) 635-1591 | |
| May 19 | 8a-11a | St John | McGregor's | Rick Bafus | (509) 648-3218 |
| 1p-3p | Dusty | Dusty Farm Co-Op Inc. | John Stoner | (509) 397-3111 | |
| May 22 | 9a-3p | Outlook | Snipes Mtn. Trans. Stn. | Mark Nedrow | (509) 574-2472 |
| May 23 | 8:30a-3p | Yakima | Terrace Hts. Landfill | Mark Nedrow | (509) 574-2472 |
| May 30 | 8a-Noon | Quincy | Wilbur Ellis | Dale Martin | (509) 787-4433 |
| 2p-5p | Quincy | Quincy Flying Service | Richard Weaver | (509) 787-3223 | |
| May 31 | 8a-10a | Ephrata | The Crop Duster | Martin Shaw | (509) 754-3461 |
| 1p-4p | Wilbur Airport | Greg's Crop Care | Greg Leyva | (509) 647-2441 | |
| June 1 | 8a-10a | Davenport Airport | Northwest Aviation Inc | Lee Swain | (509) 725-0011 |
| 1p-3p | Harrington | Western Farm Service | Jim Baye | (509) 253-4311 | |
| June 2 | 8a-10a | Ritzville | Cenex Grange Supply | Dale Anderson | (509) 659-1360 |
| 1p-3p | Odessa | Cenex Grange Supply | Greg Luiten | (509) 982-2693 | |
| 4p-6p | Lind | Rudy's Aviation | Rudy Fichtenberg | (509) 677-8858 | |
| June 5 | 8a-10a | Mattawa | Wilbur Ellis | Al Hilliker | (509) 932-4988 |
| 11a-Noon | Royal City | Saddle Mountain | Mike Pack | (509) 346-2291 | |
| 2p-5p | Royal City | Cenex | Ted Freeman | (509) 346-2213 | |
| June 6 | 8a-1p | Othello Airport | Conner Flying Inc. | Mark Conner | (509) 488-2921 |
| 1p-2p | Othello | B&H Chemical | Larry Hawley | (509) 488-6576 | |
| 3p-5p | Bruce | Cenex | Lori Anderson | (509) 488-5261 | |
| June 7 | 8a-11a | Moses Lake | Tom Dent Aviation | Tom Dent | (509) 765-6926 |
| 2p-5p | Warden | D&S Crop Care | David Smith | (509) 349-7660 | |
| June 8 | 1p-3p | Almira | Cenex | Don Felker | (509) 639-2421 |
| June 9 | 8a-11a | Wenatchee | Fieldmen's Assoc. | Floyd Stutzman | (509) 669-0420 |
| June 13 | 8a-Noon | Prosser | Simplot | John Cullen | (509) 837-6261 |
| 2p-5p | Sunnyside | Bleyhl Farm Service | Gary Herdon | (509) 839-4200 | |
| June 14 | 8a-Noon | Zillah | Bleyhl Farm Service | Ray Oversby | (509) 829-6922 |
| June 19 | 8a-10a | Spokane | WSDA | Tim Schultz | (509) 533-2690 |
| 222 N Havana | WSU | Jim Lindstrom | (509) 533-2686 | ||
| 11a-1p | Mead | Cenex | Todd Race | (509) 466-5192 | |
| 3p-5p | Deer Park | Inland Agronomy | Jim McAdam | (509) 276-2611 | |
| June 20 | 8a-9a | Fairfield | Wilbur Ellis | Ric Murison | (509) 283-2411 |
| 10a-11a | Waverly | Wilbur Ellis | Monte Bareither | (509) 283-2432 | |
| 1p-3p | Tekoa | McGregor's | Charles Wedin | (509) 284-5391 | |
| June 21 | 8a-10a | Oakesdale | Wilbur Ellis | Jerry Jeske | (509) 245-4511 |
| 11a-1p | Rosalia | Western Farm Service | John Hartley | (509) 523-6811 | |
| 3p-5p | St John | McGregor's | Rick Bafus | (509) 648-3218 | |
| June 22 | 8a-Noon | Colfax | Grange Supply | Darrel Tyler | (509) 397-4353 |
| June 23 | 8a-10a | Pullman | McGregor's | Larry Schlenker | (509) 332-2551 |
| 11a-1p | Palouse | Dale's Flying Service | Dale Schoeflin | (509) 878-1531 | |
| June 30 | 10a-Noon | Quincy | Cobia Spray Service | Jim Cobia | (509) 785-6771 |
| 1p-4p | Warden | Wilbur Ellis | Norman Parton | (509) 349-2333 | |
| July 3 | 8p-11p | Harrah | Ag Air | Lenard Beierle | (509) 865-1970 |
| July 10 | 8a-Noon | Walla Walla | McGregor's | Gary Burt | (509) 529-6787 |
| 1p-3p | Waitsburg | McGregor's | Terry Jacoy | (509) 337-6621 | |
| July 12 | 8a-10a | Prescott | Agri Northwest | Shawn Elder | (509) 547-8870 |
| 11a-2p | Prescott | Broetje's Orchard | Joe Shelton | (509) 749-2217 | |
| Prescott | Flat Top Ranch | Dave Hovde | (509) 547-9682 | ||
| 3p-5p | Pasco | Air Trac | Gerald Titus | (509) 547-5301 | |
| July 13 | 8a-11a | Eltopia | Wilbur Ellis | Vern Record | (509) 297-4291 |
| 1p-3p | Eltopia | Eastern Wa Spray Serv. | Willis Maxon | (509) 297-4387 | |
| July 14 | 8a-Noon | Connell | B&R Crop Care | Chris Eskildsen | (509) 234-7791 |
| 1p-3p | Pasco | Pfister Crop Care | Steve Pfister | (509) 297-4304 | |
| July 17 | 8a-10a | Oroville | Northwest Wholesale | Herb Teas | (509) 662-2141 |
| 11a-3p | Tonasket | Wilbur Ellis | Brian Hendricks | (509) 682-5315 | |
| July 18 | 8a-10a | Okanogan | Okanogan Air Service | Bill Lockwood | (509) 422-2617 |
| 1p-4p | Brewster | Wilbur Ellis | Brian Hendricks | (509) 682-5315 | |
| July 19 | 8a-Noon | Chelan | Wilbur Ellis | Brian Hendricks | (509) 682-5315 |
| July 20 | 8a-Noon | Yakima | Wilbur Ellis | Doug Whitner | (509) 248-6171 |
| July 31 | 8a-11a | Wilbur Airport | Greg's Crop Care | Greg Leyva | (509) 647-2441 |
| 2p-4p | Davenport Airport | Northwest Aviation Inc | Lee Swain | (509) 725-0011 | |
| Aug. 1 | 8a-11a | St John | McGregor's | Rick Bafus | (509) 648-3218 |
| 2p-4p | Mockonema | McGregor's | Dale Deerkop | (509) 635-1591 | |
| Aug. 2 | 8a-11a | Garfield | Cascade Flying Service | Doran Rogers | (509) 635-1212 |
| 1p-4p | Palouse | Dale's Flying Service | Dale Schoeflin | (509) 878-1531 | |
| Aug. 3 | 8a-10a | Pullman | McGregor's | Larry Schlenker | (509) 332-2551 |
| 1p-3p | Dusty | Dusty Farm Co-Op Inc. | John Stoner | (509) 397-3111 | |
| Aug. 4 | 8a-11a | Clarkston | Valley Helo Service | James D. Pope | (509) 758-1900 |
| 1p-3p | Pomeroy | McGregor's | Mark Welter | (509) 843-1468 | |
| Aug. 8 | 8a-11a | Dayton | McGregor's | Doug Wendt | (509) 382-4704 |
| 1p-4p | Waitsburg | McGregor's | Terry Jacoy | (509) 337-6621 | |
| Aug. 9 | 8a-11a | Eltopia | Wilbur Ellis | Vern Record | (509) 297-4304 |
| 1p-3p | Pasco | Pfister Crop Care | Steve Pfister | (509) 297-4304 | |
| 4p-5p | Pasco, Kahlotus Rd. | Air Trac | Gerald Titus | (509) 547-5301 | |
| Aug. 10 | 8a-10a | Eltopia | Eastern Wa Spray Service | Willis Maxson | (509) 297-4387 |
| 11a-2p | Connell | B&R Crop Care | Chris Eskildsen | (509) 234-7791 | |
| 4p-6p | Othello | B&H Ag Chemical | Larry Hawley | (509) 488-6576 | |
| Aug. 11 | 8a-11a | Othello Airport | Conner Flying Inc. | Mark Conner | (509) 488-2921 |
| 2p-5p | Moses Lake | Moses Lake Air Service | Perry Davis | (509) 765-7689 | |
| Aug. 14 | 8a-11a | Quincy | Wilbur Ellis | Dale Martin | (509) 787-4433 |
| 1p-3p | Quincy | Quincy Flying Service | Richard Weaver | (509) 787-3223 | |
| Aug. 15 | 8a-10a | Royal City | Cenex | Ted Freeman | (509) 346-2213 |
| 11a-1p | Royal City | Saddle Mountain | Mike Pack | (509) 346-2291 | |
| 2p-5p | Mattawa | Wilbur Ellis | Al Hilliker | (509) 932-4988 | |
| Aug. 16 | 8a-11a | Ephrata | The Crop Duster | Martin Shaw | (509) 754-3461 |
| 1p-3p | White Trail | The Crop Duster | Martin Shaw | (509) 754-3461 | |
| Aug. 21 | 8a-11a | Toppenish | Western Farm Service | Steve Laws | (509) 865-2045 |
| 1p-4p | Harrah | Husch & Husch | Allen Husch | (509) 848-2951 | |
| Aug. 22 | 8a-11a | Cowiche | D&M Chemical | Dee Gargus | (509) 678-5750 |
| Sept. 5 | 8a-11a | Chelan | Northwest Wholesale | Herb Teas | (509) 662-2141 |
| Sept. 6 | 8a-11a | WenatcheeTree Fruit Stn. | Fieldmen's Assoc. | Floyd Stutzman | (509) 669-0420 |
| Sept. 11 | 9a-11a | St John | Gossard Aviation Inc. | Wesley Gossard | (509) 648-3722 |
| 1p-3p | Pine City | Reed Aviation | Pete Reed | (509) 523-3950 | |
| Sept. 12 | 8a-10a | Warden | Kilmer Crop Dusting | Terry Kilmer | (509) 349-2491 |
| 11a-1p | Bruce | Simplot | Chuck Spytex | (509) 488-2132 | |
| 3p-5p | Othello | South Saddle Orchard | Mike Macy | (509) 539-5836 | |
| Sept. 14 | 8a-11a | Zillah | Bleyhl Farm Service | Ray Oversby | (509) 829-6922 |
| Oct. 3 | 9a-10a | Ellensburg | DOT | Susanne Tarr | (509) 962-7577 |
| Oct. 13 | 8a-3p | Othello | Conner Flying Inc. | Mark Conner | (509) 488-2921 |
| Oct. 16 | 8a-10a | Waterville | Western Farm Service | Dale Gromley | (509) 745-8857 |
| 11a-2p | Coulee City | Western Farm Service | Pete Thiry | (509) 632-5697 | |
| 3p-5p | Ephrata | The Crop Duster | Martin Shaw | (509) 754-3461 | |
| Oct. 17 | 8a-11a | Wilbur Airport | Greg's Crop Care | Greg Leyva | (509) 647-2441 |
| 1p-4p | Davenport Airport | Northwest Aviation Inc. | Lee Swain | (509) 725-0011 | |
| Oct. 18 | 8a-Noon | Rosalia | Western Farm Service | John Hartley | (509) 523-6811 |
| 1p-3p | Mockonema | McGregor's | Dale Deerkop | (509) 635-1591 | |
| Oct. 19 | 8a-10a | Connell | B&R Aerial Crop Care | Chris Eskildsen | (509) 234-7791 |
| 1p-3p | Pasco, Kahlotus Rd. | Air Trac | Gerald Titus | (509) 547-5301 | |
| Oct. 23 | 8a-10a | Spokane | WSDA | Tim Schultz | (509) 533-2690 |
| 222 N Havana | WSU | Jim Lindstrom | (509) 533-2686 | ||
| 11a-1p | Mead | Cenex | Todd Race | (509) 466-5192 | |
| 3p-5p | Deer Park | Inland Agronomy | Jim McAdams | (509) 276-2611 | |
| Oct. 26 | 9a-Noon | Coulee City | Cenex | Huck Dilling | (509) 632-5292 |
| 1p-3p | Almira | Cenex | Don Felker | (509) 639-2421 | |
| Oct. 27 | 8a-Noon | Moses Lake | Tom Dent Aviation | Tom Dent | (509) 765-6926 |
| 2p-5p | Warden | Kilmer Crop Dusting | Terry Kilmer | (509) 349-2491 | |
| Oct. 30 | 9a-3p | Outlook | Snipes Mtn. Trans. Stn. | Mark Nedrow | (509) 574-2472 |
| Oct. 31 | 8:30a-3p | Yakima | Terrace Hts. Landfill | Mark Nedrow | (509) 574-2472 |
Return to Table of Contents for the April 2000 issue
In reviewing the February postings in the Federal Register, we found the following item that may be of interest to the readers of Agrichemical and Environmental News.
In the February 8 Federal Register, EPA announced that in accordance with an agreement reached with AgrEvo, the registrant is requesting both use deletions for its formetanate hydrochloride-containing insecticides and some product cancellations. (The product cancellations involve SLNs.) The proposed use deletions cover plum and prune use, as well as greenhouse grown ornamentals. (Page 6208)
In the February 11 Federal Register, EPA announced the availability of PR Notice 2000-1. This document clarifies EPA's policy with respect to the applicability of the "treated articles exemption" in 40 CFR 152.25(a) to antimicrobial pesticides. A copy of this document is available electronically at http://www.epa.gov/pesticides/ under the February 11 information. (Page 7007)
In the February 22 Federal Register, EPA announced that revised risk assessments were available for acephate and methamidophos. Electronic copies of both can be accessed at http://www.epa.gov/oppsrrd1/op/status.htm. Comments on these documents are due to EPA on or before April 24, 2000. (Page 8702)
On October 21, 1999, EPA reopened the comment period on the proposed rule "Standards for Pesticide Containers and Containment" to obtain comment on four specific issues. On December 21, 1999, EPA extend the comment period by 60 days until February 19, 2000. EPA is now reopening the comment period for an additional 30 days until March 20, 2000. (Page 9234)
The PNN is operated by WSU's Pesticide Information Center for the Washington State Commission on Pesticide Registration. The system is designed to distribute pesticide registration and label change information to groups representing Washington's pesticide users. PNN notifications are now available on-line. To review those sent out in the month two months prior to this issue's date, either access the PNN page via the Pesticide Information Center On-Line (PICOL) Main Page on URL http://picol.cahe.wsu.edu/ or directly via URL http://www.tricity.wsu.edu/~mantone/pl-newpnn.html. We hope that this new electronic format will be useful. Please let us know what you think by submitting comments via e-mail to Jane Thomas at jmthomas@tricity.wsu.edu.
Chemical (type) |
Federal Register |
Tolerance (ppm) |
Commodity (raw) |
|
||
Yes/No |
New/Extension |
Expiration Date |
||||
| imidacloprid (insecticide) | 16-Feb-00 pg 7737 | 0.2 | sweet corn, fodder | Yes | New | 12-31-01 |
| 0.05 | sweet corn, grain | |||||
| 0.1 | sweet corn, forage | |||||
| Comment: These time limited tolerances are being established in response to EPA granting a Section 18 exemption for the use of imidacloprid to control flea beetles on sweet corn seed in Minnesota and Idaho. EPA has authorized the corn seed to be planted in states where the corn flea beetle is creating an emergency situation. | ||||||
| zinc phosphide (rodenticide) | 23-Feb-00 pg 8872 | 1 | alfalfa, forage and hay | Yes | Extension | 12-31-02 |
| Comment: This time-limited tolerance is being extended in response to EPA granting a Section 18 for the use of zinc phosphide to control voles in California alfalfa. This action also amends the tolerance, raising it from 0.1 ppm to 1.0 ppm. The amendment is necessary because the request is for a new use pattern. | ||||||
W.S.U. Pullman Home Page Comments and questions: cdaniels@tricity.wsu.edu Technical Assistance: scoates@tricity.wsu.edu Copyright © Washington State University / Disclaimer Electronic Publishing and Appropriate Use Policy University Information: 509/335-3564