Anything Scary About California's Produce Options This Halloween?

California Food Safety Check

Each year the California Department of Pesticide Regulation (CalDPR) collects produce samples from multiple steps between the farmers and consumers. They recently released their results for 2018.  They tested a total of 3,666 samples of 140 different crops grown in California, other US states and items that were imported from 25 different countries.  For each sample they analyzed for 400 different pesticides or their known breakdown products.  This is also part of an enforcement program so it is great that they are still so transparent with their findings.

As with previous surveys, the results document the fact that the growers who produce our food are following the EPA label requirements that are designed to insure that by the time it gets to consumers is quite safe.  That safety standard is based on national standards set by the EPA.  For 78% of the crops there we either no detectable residues or residues below the legal limits. Few of the remaining examples were at all problematic

Particularly for the US grown samples, excessive concentrations were very rare.  There were some residues of chemicals found which are not technically supposed to be used on that crop, and as in the past most of these “no established tolerance” cases were on the imported items.  

The residue issues varied quite a bit by source. Those from different parts of the US were similar, but those from China, Mexico and Central America had more cases of "no tolerance." Perhaps the best profile was for crops imported from South America.

301 of the items were being sold as “Organic.”  The rule for organic set by the USDA is that no detected residues should exceed 5% of the EPA tolerance .  In 2018 only 55.4% of detections from organic sample met that standard so they should not have been able to be sold as "USDA Organic Certified."  Imported organic residues over 5% of the tolerance made up 66.7%  of detections which is very similar to that same measure for domestic conventional produce.  55.4% of the detections on imported conventional crops would not have disqualified them if someone was trying to sell them as organic.  Below is the list of specific pesticide residues that were found on organic samples.   

AMETOCTRADIN 1, BIFENAZATE 1, BIFENTHRIN 1, CAPTAN 1, CHLORPROPHAM 2, CYAZOFAMID 1, CYPERMETHRIN 1, CYPRODINIL 1, CYROMAZINE 1, DDE 5, DIELDRIN 1, FENAMIDONE 1, FLONICAMID 2, FLUBENDIAMIDE 1, FLUDIOXONIL 4, FLUOPICOLIDE 1, FLUOPYRAM 3, FLUPYRADIFURONE 1, IMIDACLOPRID 2, MANDIPROPAMID 1, PENDIMETHALIN 1, PENTHIOPYRAD 1, PERMETHRIN 2, PROPAMOCARB 1, PYRACLOSTROBIN 1, PYRIMETHANIL 1, ROTENONE 2, SPINOSAD 16

Those who think they are buying something safer by spending more for organic might want to rethink that logic. Only the 16 spinosad detections represent something allowed for use on organic, and organic still has the legacy of residual DDT metabolites like DDE.

While CalDPR made it very clear that this report was good news, they called out seven commodities for which they though the residues could be a legitimate health concern. These are Dragon Fruit (Vietnam), Chayote (Mexico), Lychee (China), Cactus Pear (Mexico), Star Apple (Vietnam)m and Tomatillo (Mexico).  They also added Star Apple from Vietnam  and Guaje from Mexico because of products found there for which there is no set tolerance.

Once again this is evidence that our food supply is safe and also incredibly diverse. This testing program is different from the USDA’s Pesticide Data Program (PDP) in that it includes a number of more exotic items. However it also includes many more mainstream fruits and vegetables and among those there were no above-tolerance detections. But in both cases the take-away is that we should enjoy our fruit and vegetable options and consume them as part of a healthy lifestyle.

                                                                                                                                        

Exterminate!

(This piece was originally posted on the POP Agriculture Podcast 9/19/2019)

The Tardis (photo by Zir, Wikimedia Commons)

The show has been running on the BBC since 1963, and part of what makes that long run possible is that the Doctor has the ability to be re-born from time to time with a different human body (although supposedly with two hearts).  There have been 13 different stars playing the part of The Doctor, and the most recent one is Jodie Whittaker (#13), the first female. I just finished binge watching that season to catch up! Other recent leads have been David Tennant (#10), Matt Smith (#11), and Peter Capaldi (#12).

Hard core Doctor Who fans call themselves “Whovians,”   The Urban dictionary puts it this way:  “A few easy ways to tell if someone is a Whovian are: Turn off all the lights while repeating "Hey, who turned out the lights?", moving statues around while they aren't looking or telling them not to blink while staring at a statue, yelling exterminate at them in a freaky as hell robot voice, and watching how they react. If they start screaming they're most likely a Whovian.” 

So, what’s the “exterminate” thing about?  There are new and different “bad guys” for the Doctor to out-wit in most episodes, but throughout the years of shows, a frequent “threat to the future of humanity” has been a strange race of robotic space beings called the Daleks.  Back in the earliest, obviously low budget days of the show, the Daleks looked a lot like modified trash cans (I guess “dust bins” since it’s British) with toilet plungers for arms.  That basic, funky, Daleck look has been preserved over the history of the show as has that creepy chant that of theirs: “Exterminate! Exterminate! ….” 

Dalek image by Nelo Hotsuma from Rockwall [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)]

So the Daleks of Dr. Who are a classic example of fictional, pop-culture aliens who are out to exterminate humans. There are also many examples of pop-culture stories of humans trying to “exterminate” some sort of alien invaders.  On today’s POPagriculture podcast we are going to talk about a real world story about how humans successfully managed to “Exterminate” some alien invaders who were threatening the grape industries of California.

Standard Intro

So, in California there are lots of farmers who tend 880,000 acres of grapes.  These include those that are specifically for drying to make raisins.  Other grapes are grown as a nice, fresh, mostly seedless snack.  Throughout the state there are also various “appellations” for wine grape production.  Together these crops bring in about 5.8 billion dollars a year to the state’s economy. These products are loved by not just Americans but by people around the world.  California has nearly ideal climatic conditions for each of these grape categories, and since they are relatively drought tolerant they are a good fit for our limited water resources.  One nice thing is that we don’t have much rain during the summer and so we don’t have to deal with some difficult fungal diseases that are a big challenge in places like Europe.  There are still certainly pests that have to be dealt with, but the grape industry has always been a leader in doing that is a sustainable way.

Lobesia: European Grapevine Moth image by Jack Kelly Clark, University of California Extension

So that’s the background, but the drama for our story began in the summer of 2009 in a famous, premium wine grape-growing region called the Napa Valley.  One of the growers there spotted a caterpillar munching away on some of his grapes.  Now there are several kinds of moths that can be pests of California grapes, particularly during their larval stage as caterpillars.  But the grower noticed that this one didn’t look like those familiar types. Being suspicious he sent a picture to a county extension agent – a kind of University employee whose job it is to support the industry with research and advice.  It turned out that was a new kind of moth to California – an alien invader!  Ok, not a space alien, but scary from the perspective of grape farmers.  It was called the European Grapevine Moth or “EVGM.” As its name implies it has been a pest in that continent for a long time.  That name doesn’t sound scary enough for our story so lets use the scientific name, Lobesia botrana.

Now the thing is that this wasn’t just another moth.  The caterpillar stage of this bug would do a lot more damage to the grape clusters than the other moth species and that would mean nice things like “frass” or insect poop on the grapes or later the raisins.  To make matters worse, the feeding opens the way for fungi that rot the grapes and that kind of infection can spread from berry to berry throughout the cluster.  This would make it a lot harder for the raisin growers to have a high quality product, it would mean a lot more food waste even all the way to the consumer level for the table grapes.  Moldy grapes definitely don’t make for high quality wine!

Rotting grape image by Andrea Lucchi, University of California

 

Now of course there wasn’t an extraterrestrial “Doctor” to lead this campaign, but even Dr. Who drafts a team of regular humans to help defeat the aliens.

In this case the team comprised representatives of the grower communities, university experts and government employees from the relevant state and federal departments. They held an emergency meeting and decided that they wanted to see if they could come up with a way to not only stop the spread of the pest, but if at all possible to completely eradicate it from California.  Eradicate! Doesn’t sound quite as harsh as “exterminate!” but it’s essentially the same idea.

 

 

In order to see what they were up against, sixty thousand “Sticky traps” were distributed state wide at a density of 39 per square kilometer in vineyards and 10 per square kilometer in residential areas. In the next 2010 growing season they found 100,000 moths in several California counties.  This was going to be a big challenge!  Only a comprehensive strategy with broad participation would give any hope of winning.  So the team developed a multi-prong strategy:

 

Those sticky traps continued to be used to monitor progress, but they were careful to use red colored traps because they are much less likely to accidentally trap honeybees.

 

It was important to find ways to limit further spread of the aliens. The adult moths can fly, but they don’t tend to fly too far as long as they can find the grapes they want. Quarantine rules were set up to prevent fruit, farm equipment, recycled fence or grape posts, or other things that might allow the pest to hitch-hike long distances. It turned out that the moth larvae could survive the stemming and crushing and even pressing of wine grapes – so it was critical not to move around those by-products of the winemaking process.

 

They also used an approach called “pheromone confusion” that was set up on an area-wide basis where the Lobesia had been found.  This involves putting up emitters of the specific sex hormone for this moth so that the males are getting so many “scent trails” that they rarely actually find a female to actually mate. 

 

There were lots of outreach programs to get everybody up to speed on the situation and to know their role.  This included grape growers, wineries, and fruit or raisin packers, and pest control advisors. The outreach also had to include on the order of 3,000 homeowners because they also needed to cooperate, especially if they had backyard grapes, as many did. The coordinated task force would help those owners to treat their grapes or remove their fruit so that they didn’t become a reservoir to then fan out into the commercial vineyards. Not only were there public meetings to reach all these groups, there was a Facebook page and a website at www.bugspot.org.

 

The researchers developed a sophisticated “degree day model” to predict when each of the 3-4 new generations of moths would be coming out so that insecticide sprays could be timed just right, not only to protect the crop, but to prevent the moth numbers from really blowing up as they would if not strategically checked this way.  Almost all of this spraying was done on a voluntary basis at the grower’s own cost.  In Napa and Sonoma in 2012 the growers treated more than 12,000 acres.  The organic growers also sprayed using the insecticide options that are allowed under their rules.  

 

The combination of the quarantines, the pheromone confusion and the well-timed insecticide sprays achieved what is called an “allee effect” in population biology lingo.  This is when the population size gets down to the point where there are too few of the pests in a given area to successfully mate.

 

 Historical progress towards eradication of EVGM from California. University of California.

This massive, voluntary, cooperative effort was highly coordinated across the different counties of the state and it began to pay off.  In 2011 there were 2,335 acres quarantined because of the presence of the moth.  By 2014 that number was down to 446 acres.  By 2016 the pest was officially declared to have been eradicated.

Victory Lap! (University of California)

 

 

In the Dr Who shows the Daleks don’t ever seem to manage to “eliminate” humans, but in this story the humans managed to “eliminate” the alien pest. 

 

There have been some other historical examples where the humans were able to “exterminate” a new insect pest.  Another strategy that was used in some of these battles was the intentional release of sterile males of the pest species so that they so that they would out-compete the wild males trying to breed with the wild females.  This helped when the Mediterranean Fruit Fly came to California several times over the years.   

 

Another pest eradication success story had to do with a pest of cotton called the Pink Bollworm.  In that case in addition to the release of sterile males, pheromone confusion, area-wide “plow downs” and strategic sprays, the growers also had the opportunity to use lines of “Bt cotton,” genetically engineered to be resistant to the pest. 

 

Now unfortunately, it will never be possible to have this sort of victory over all the pests of grapes or any crops for that matter.  Still, when growers are only up against a familiar set of pests, they can achieve a sufficient degree of control to protect their livelihood, keep food affordable, and prevent the pest-related quality or food safety problems that would otherwise flow on down to the consumer level.

 

 

 

 

 

 

 

Florida Citrus Industry Is Facing An Existential Threat From Bacteria, But A Virus Offers Hope

Orange Juice (Image by AlbanyColley, Pixabay)

(This article was originally posted on Forbes on 4/30/19) When I was growing up in the early 1970s there was a ubiquitous television ad promoting Florida orange juice including the line, "a day without orange juice is like a day without sunshine." That "dark day" could be approaching soon, at least in terms of the juices we get from the "Sunshine State" and the livelihood of the farmers who grow the trees that have long supplied us.

The iconic orange juice industry in Florida is facing an existential threat because of a severe bacterial disease of citrus that was introduced to the US from Asia in 2005 (the Asian Citrus Psyllid insect that helps to spread it was first found in Floria in 1998). A Florida homeowner may have inadvertently introduced the bacterium to the US in citrus budwood he brought home from Asia to graft onto his backyard trees.  The malady is often called "Citrus Greening," but in Asia it is known as Hualongbong and so we now tend to call it HLB. HLB has since spread to virtually all the back yard and commercial citrus trees in Florida, killing many of the trees and forcing the growers to struggle to keep the remaining ones alive with intensive nutrient feeding and other stop-gap measures.  

Oranges showing symptoms of "Greening" or HLB (USDA image)

In 2013 journalist Amy Harmon wrote an excellent article for the New York Times about the history of this crisis titled: "The Race To Save The Orange By Altering Its DNA."  She described in detail how this long-anticipated threat finally materialized and how the Florida growers funded university research to explore possible solutions including genetic engineering.  A biotech solution was identified using some defensive peptides that are naturally made by spinach plants, but as Harmon explained, that sort of "GMO" solution was a hard sell to the big, brand-sensitive juice companies who buy the oranges.  I have been personally disappointed to watch the way that the juice companies have acquiesced to the pressure to use a "non-GMO" label.  That unfortunate marketing ploy now appears on all the brands including the one company that relies exclusively on Florida fruit as opposed to a mix with imports. This is a classic case of how "control of the food supply" is really the in the hands of anti-technology activist groups, not the big companies most often so accused.

This is my current bottle of FL grapefruit juice, but I have to "hold my nose" when buying in because of the misleading "non-GMO" label (Ruby Red grapefruit was generated using mutagenesis breeding, no a problem but definitely "genetically modified")

But realistically, deploying a biotech trait like this in a perennial crop would be quite slow because the growers would have to start over with new trees or possibly graft onto the existing rootstocks and regrow the entire above ground part of the plant.  In the mean time, the industry has been steadily declining and the fear is that it will reach a point where it just isn't worth maintaining the juice plants.  Orange juice can certainly be imported, but for a time the Florida industry was able to distinguish itself by its better tasting "not-from-concentrate" advantage.  

This same destructive disease now threatens the citrus industries in other states.  The disease and its insect vector are already present in California, but for now it has been contained to mostly urban/suburban areas in the southern part of the state.  If it spread to something like the tangerine/mandarin groves of the Central Valley and other parts of the $3.4 Billion California citrus industry, that would be a disaster (think Cuties(r), Halos(r), lemons, navel oranges, grapefruit etc.)

From my current bag of mandarins (again sadly with the misleading non-GMO label)

But I'm happy to say that today I'm writing about a newer technological approach to deal with this disease.  An extended public comment period ran through Tuesday May 30th in which the USDA asked for feedback on the question of whether or not to approve the commercial deployment of a different way to protect orange trees from the HLB disease.  It is something which could possibly be implemented much more quickly than by genetically engineering the trees themselves.  This is something that could be presented in a way that would make it sound scary, but its really not. 

There is a virus that infects orange trees called Tristezea.  It also came from outside the US and began causing problems in all the citrus growing regions of the US in the 1960s.  At first it was also a lethal disease, but eventually it was found that by avoiding certain rootstock types, the virus could infect the trees with no symptoms at all.  (Virtually all fruit crops have been grown on rootstocks for a centuries).  In Florida today all but the youngest trees are infected with Tristeza, but with strains that are benign for trees when they are on the rootstocks now used.  The new biotech solution is to add genetic sequences for the spinach antimicrobial peptides to the RNA of the virus, and then get that virus to infect orange trees.  This could be done with new trees when they are in nurseries, but it may be possible to also "graft transmit" the virus into at least they younger trees already out in the commercial groves.  In this case that new small branch does not need to take over, it just allow the virus+peptides to move into the other parts of the existing trees.  In any case, modifying the virus is far more efficient than having to separately engineer and propagate each of the popular citrus varieties in the industry.

A small scale trial that was run for several years confirms that this sort of virus inoculation can make the trees resistant to the HLB pest and to allow full productivity.  As part of that experiment, trees with no virus were planted all around these test blocks and then followed to see if the engineered virus ever moved into them (the virus can be transmitted by aphids under certain circumstances).  In fact the virus didn't move, though even if it did it wouldn't be a big issue.  Also, over time the modified virus loses the genes for the spinach peptides which is then another barrier to any sort of unwanted spread.  Also it is clear that the Tristezea virus does not have any bad effects on other crops or wild plants since the virus has been very widespread for decades without causing problems in other species.

I've included the comments that I submitted to the USDA below concluding with my hope that the experience in Florida will pave the way for using a similar approach in California if we ever have to save that industry as well. I sincerely hope that the USDA does approve this new method and I sincerely hope that those who control the juice plants will both help the growers that supply them and trust consumers to be smart enough to listen to the logic about this technology.

This is the Website about the USDA comment process:

--> https://www.aphis.usda.gov/aphis/ourfocus/biotechnology/brs-news-and-information/2019_brs_news/ctv_reopen_april2019
This is the link for comments followed by what I submitted:


-->

The Animal and Plant Health Inspection Service (APHIS) Notice: Environmental Impact Statements; Availability, etc.: Preliminary PestRisk Assessment for Permit for Release of Genetically Engineered CitrusTristeza Virus

I am writing in support of this release permit as I believe that it is a very logical strategy with the potential to literally save the citrus industry in Florida. If it proves successful it could play a similar role in the unfortunately likely scenario that HLB becomes a more serious threat to citrus production in other regions such as California. I am a plant pathologist with a Ph.D. from the University of California, Davis. My own work there was with fungal diseases, but I spent a lot of time in the lab of Dr. Robert Shepherd, a National Academy virologist. Starting at that time in the late 1970s I had many close colleagues who were working on the early stages of plant genetic engineering and I have continued to follow that field ever since. The progress of the field has been remarkable. 

In preparation for this comment I read all the available documents from the USDA site and corresponded with some of the university researchers who have done the relevant work on issues like the potential for recombination and transmission of the modified Tristeza virus.

This approach of using an asymptomatic strain of the virus is particularly logical for this perennial crop. To engineer the orange scion itself would require the generation of separate "events" in each of the important cultivars and then a delay to graft those onto existing trees and bringing that new "top" into bearing. Using the virus makes it far more feasible to utilize more than one combination of antimicrobial peptides which will help to prevent the development of resistance in the HLB bacterial pathogen population. 

There are several convincing reasons that this strategy is likely to be safe with regard to any potential for spread to non-target citrus or to other plant species. There is very low rate of aphid transmission even under ideal lab conditions. The track record of zero transmission to sentinel plants in the previous limited release further demonstrates that the modified virus is extremely unlikely to move beyond the intended trees. The fact that recombination will likely lead to loss of the peptide part of the viral genome is another safety factor and will again allow for the deployment of different peptides in a follow-up grafting step if that is needed down the line. The fact that the Tristeza strains to be used are already ubiquitous in Florida citrus represents a multi-decade "experiment" showing that this virus represents no threat to other species or to citrus that is grown on the rootstocks for which infections by these strains are asymptomatic. With the tremendous advances in the speed, sensitivity and affordability of genetic assays, it will be possible to rigorously monitor the efficacy and safety of the strategy. As for the anti-microbial peptides from spinach - long experience supports their safety from a food point of view.

I believe that this release can be the culmination of an exemplary example of an effort funded by the grower community and partnering with the public, academic community to employ state-of-the-art science.

A Closer Look At Organic Pesticides In California

I've posted an article on Forbes taking a general look at the role of organic-approved classes of pesticides in California.  The take-home points are that pesticide actives that are approved for use in organic made up 55% of the total crop use in 2013 and that those are used by both organic and conventional growers.  I also take a look at the relative toxicity (simple acute ingestion toxicity) and there is a similar range for the organic and synthetic options.  None of this is surprising because what determines whether a pesticide can be "organic" is whether it is "natural", and that is not a safety-based criterion.  The safe use of all pesticides is the responsibility of the EPA and similar regulators around the world.

In this post I'd like to delve in more detail into what these widely used organic pesticides are and why they are used by all sorts of growers.

Major Categories of Organic-Approved Pesticides

In the first graph in this post I've divided the organic-approved materials into Mineral-based, Oil-Based, Natural Products and Live Biologicals.  I'll talk about each category below.

Mineral-Based Pesticides

The mineral-based pesticides that are approved for organic include sulfur, lime-sulfur, and various forms of copper. Together these materials comprise 34% of the pounds used but only 12% of the area treated. That is because these are relatively high use-rate materials (~2 to 25 pounds/acre).

Sulfur has been used as a pesticide since ancient times. While it is essentially non-toxic by ingestion, as someone who has worked long hours in treated vineyards, I can tell you that it is quite irritating to the eyes and skin. Sulfur controls powdery mildew fungi and suppresses spider mites, but has to be reapplied every 7-10 days. It works by sublimation (direct transition from solid to gas) so it is ineffective if it is cold and can burn the crop if it is very hot. It is converted into reactive sulfur compounds in the humid boundary layer of a leaf or berry.  Conventional growers have alternatives that need only be applied at ounces/acre every 14-21 days, but continue to use some sulfur in their programs as a way to manage resistance to the newer materials (see chart below for the trend in sulfur use on premium California grapes).

Conventional grape growers today use about 1/3 as much sulfur because they have other options

The next big mineral-based material is lime sulfur.  It is used for some dormant season sprays, so its “moderately toxic” status (EPA Class II) is not an issue for crop residues.  The remaining organic mineral pesticides are the copper-based fungicides which were discovered in the late 1800s and actually saved the European grape industry when a downy mildew pathogen was introduced from the New World. Some of the copper products are Class II in terms of oral toxicity, can be persistent, and are toxic to aquatic invertebrates, but with appropriate care for where they are used, they are considered safe . Again, conventional growers have lower rate, longer interval, more effective options, but use some copper for resistance management. Coppers are also one of the few options for the control of certain bacterial diseases and for algae control in rice fields.

Petroleum Oil-based Products

An interesting organic-approved category is a collection of oils derived from petroleum (mineral oil, paraffinic oils, petroleum distillates…). These too are relatively old products used at high rates, but they are effective on mites, aphids, whiteflies, scale insects and also powdery mildews. These are also EPA Category IV – “essentially non-toxic” to mammals by ingestion.  Again, they are also used by conventional growers along with other more modern options.

JMS Stylet Oil is a major organic brand in this category

Natural Products

Spinosyn-A - some seriously fancy chemistry (image via Klever)

About 2% of the acre-treatments on California crops were with various “natural products” which are chemicals that are made by plants or from fermentations of various microbes (thus qualifying them for organic). Nature is indeed a remarkable chemist, but that is not a guarantee of safety. Some of the most toxic chemicals known are from nature. The safe use of these materials is based on the same, elaborate risk assessment that agencies like the EPA conducts for all pesticides. The most widely used natural product is the plant hormone gibberellin (540,000 acre treatments). The next biggest product (309,000 acres) is Spinosad which was introduced by Dow Agrosciences. It comes from fermentation of an actinomycete. It’s a remarkably complex chemical, but very low in mammalian toxicity (Category IV) and quite effective against all sorts of caterpillars and hard to control insects like leaf miners. Unlike the mineral or oil-based pesticides, it can move inside of the treated plant to protect newly emerging leaves.  Lately it has become available to homeowners as “Captain Jack’s Dead Bug Brew” which is a sort of silly name, but definitely something I use in my garden.

The number 6 natural product (22,500 acres treated) is a relatively recently developed, plant-based natural product that comes from a plant called Epazote or American Wormseed. The small, California company that commercialized it was purchased by Bayer Chemical Company. They have since introduced a product in Europe which is made of a mixture of the same four terpene chemicals that occur in the plant extract. That sort of product often generates much debate in the organic community about whether it is still natural, but the chemicals are the same. In any case this product is effective against various insects including thrips which are difficult to control. That is why it will be increasingly used by both organic and conventional growers.

Thrips cause these feeding scars you often see on snap peas or snow peas

The smallest category of organic-approved products are the biological control agents. The most used and famous of these are various strains of the bacterium Bacillus thuringiensis, or “Bt.” These bacteria make a protein that is selectively toxic only in the guts of certain insects (e.g some work only on caterpillars, some only on beetles and some only on mosquitoes). Together, 10 Bt-based products were applied to 320,000 acres. Some crops have been genetically engineered to express these same Bt proteins, but those would not qualify for organic. Sweet corn has been modified this way, but the sweet corn growers have been asked by their retail store customers not to use the "GMO" varieties. Instead they must make at least six more sprays a season than they would need to if they could use a Bt variety. That is a shame.

The "natural" pesticides that are approved for organic also have an important role in conventional agriculture.  They are not qualitatively less toxic than synthetics, but then virtually all the pesticides used today are only moderately toxic at most and most commonly non-toxic in the classic sense. These and the modern synthetic pesticides play an important role in the efficient use of the land, water, fuel and labor that it takes to produce food. 

You are welcome to comment here and/or to email me at savage.sd@gmail.com