The European Union's Wine Grape Quandary

The European Union has recently published a lengthy "Farm to Fork Strategy" which sets out ambitious goals for its agricultural sector. One part of the agenda is to reduce the use of pesticides either by restricting the way they can be used or in many cases by not authorizing their continued use when those particular chemicals come up for periodic review by regulators. Often these restrictions are at odds with the rigorous safety assessments that have been made by many regulatory bodies around the world including the US EPA. Another part of the agenda is to encourage the expansion of Organic farming. There are several reasons why this plan will cause serious complications for European farmers, and since the EU is a major importer of food, feed and fiber crops, the restrictions that it applies to various grape pesticides will also be a problem for farmers around the world who export their crops to the EU market.

 

Many crops will be affected by this agenda, but one interesting case-study is what this push will mean for the prominent and highly regarded wine grape industry in the EU.  Wine grapes only represent around 3% of EU farmland, but around 20% of total EU pesticide use. There are several reasons for this relatively intensive use of crop protection products.  For one thing wine grapes are a very high value crop so growers can afford to use more products to optimize the yield and quality of their fruit. But there are also important historical and genetic reasons why certain pests represent a particular challenge for the European grape industry. 

 

With most crops, breeding is an important strategy to help with pest problems, notably when that involves tapping into the genetic diversity available in various wild relatives of the cultivated crop. With wine grapes the breeding option has essentially been "off-the-table" because of the long tradition which has identified very specific Old World grape varieties of the species Vitis vinifera which have been found to provide the highest quality for the weather and soil conditions of each growing region or "appellation." The long-term history and tradition of growing specific grape cultivars in each region is often called "terroir" and this is not anything the industry wants to change because it needs to meet consumer expectations and marketing narratives about wine quality.

 

Interestingly in the 1870s there was a dramatic change to the genetics of European grapes.  A root feeding insect called Phylloxera was inadvertently transported to Europe from North America. The various wild species of grapes that evolved alongside Phylloxera are fairly resistant to the damage from that specific insect pest. (The most familiar example of this kind of grape is a species called Vitis labrusca which consumers know as Concord Grapes because that is the kind of grape used to make non-alcoholic grapes juices such as the famous brand - Welches). The native American grapes are not considered to be that good for making high quality wines, but some hybrids between the two species are grown for wine in the Northern US in areas that are too cold for Vitis vinifera.  The Vitis vinifera grapes of Europe evolved without the challenge from Phylloxera so once the pest crossed the Atlantic the vineyards were highly susceptible to its damage and began a steep decline.  The only way the industry was able to be saved was by grafting the vinifera cultivars onto "American Rootstocks."  Grafting is a horticultural technique that has been practiced for centuries, but it was only with great reluctance that the European growers took that step. 

A grafted grapevine, image from Washington State University Extension

Around the world today virtually all wine grapes are grown on these "American" rootstocks because they can provide protection from soil-borne pests while allowing the traditional varieties to achieve the desired fruit qualities that made them so desirable. Rootstocks are used for almost all perennial crops and also for high value vegetable crops like fresh market tomatoes.

 

There are also two serious foliar diseases that also made the jump from North America to Europe in the 1800s. The first was a disease called Powdery Mildew and it causes loss of yield and quality as it grows on the exterior of the leaves and fruit.  Vitis vinifera is highly susceptible to this disease.

Grape Powdery Mildew infection of a developing grape cluster. Photo by Laura Jones/Univ. California, Davis

The solution that was found is probably the oldest known pesticide, elemental Sulfur.  This "natural" mineral product was found to control the disease but only if the grapes were "dusted" with something like 10 pounds/acre of sulfur every 7 to 10 days for much of the season until the fruit begins to ripen (a stage called veraison in grape-speak).  Sulfur is not very toxic to eat or drink, but it is an eye and skin irritant that can make it quite unpleasant to work in a vineyard. There is also some evidence that as with other dusts, sulfur can increase the risk of asthma among the children who live near the places were dust products are applied. California has recently restricted the use of sulfur and other dusts near populated areas. "Wettable" forms of sulfur can still be used without the respiratory problem and that is still a part of integrated pest management systems for grapes.  However; most modern grape growers use sulfur more sparingly because newer and more effective "synthetic fungicides" have been developed which require far smaller doses at longer intervals and which are in the EPA toxicity class IV described as "essentially non-toxic" by ingestion. I remember a time in 1978 during my second season being out in California vineyards for my graduate research that I was amazed to smell a beautiful floral aroma during the grape bloom period - something I had not experienced the season before. It was because I was in a block treated with the first example of these new fungicide options instead of the normal odiferous and irritating sulfur. I have a podcast about that event.  Grape growers who choose to grow for the organic market are not allowed to use these more modern tools and must therefore depend on high use-rate options like sulfur and something called "petroleum distillates" (think mineral oil for the later).  Thus, this is just one example of how the EU Field to Fork strategy embodies conflicting goals if it wants to reduce pesticide use and the push for more organic production.

Grape Downy Mildew sporulating on the bottom of a leaf. Photo by Mark Longstroth, Michigan State Univ. Extension

There was another "intruder" fungus pest that originated on North American grapes and then caused even more severe problems for the European industry in the 1870s.  It is called downy mildew.  The solution that was ultimately found to this disaster was another very early pesticide. It was discovered by a French botanist named Pierre Millarday who noticed a particular vineyard along a roadside that stood out by exhibiting much less damage from the new disease. He learned that the grower had applied copper sulfate combined with lime as a way to make the fruit look unappealing so that people passing by would stop helping themselves to his grapes (you can see an image of this blue coating in this article in Wine Spectator).  

 

That "natural" pesticide became known as the Bordeaux mix and it saved the grape industry.  It was also a much-needed solution for a related disease on potatoes that had cause the famous Irish Potato Famine in the same era.  Various copper-based products do work against these pests and many are approved for use in organic production, but unfortunately they are quite toxic to aquatic organisms and are persistent in the environment since the mineral copper is copper and it isn't going to break down to innocuous components the way that many other natural or synthetic chemicals do over time. After years of use, copper fungicides build up in vineyard soils and can become toxic to grape roots. Many European organic growers have had to abandon their organic status because of these soil issues.  Copper fungicides also require high use-rates (4-6 pounds/acre) and frequent applications because the copper is easily washed off by rain. 

 

Once again, many low toxicity, highly effective and environmentally safe synthetic fungicides that have been developed to fight downy mildew, but those options are not allowed to be used by Organic growers. European regulators are not fans of these copper fungicides, but their politicians have made exemptions for their own grape growers while at the same time setting up barriers to more benign products that have met rigorous standards in other countries.  

 

Organic growers also have limited options for the control of mold fungi that can infect the grapes as they become ripe. That sort of "bunch rot" is very bad for wine quality, but a disease that is well addressed with safe, modern synthetic fungicides while organic growers still depend on things like copper. Chemical herbicides are also desirable for grape production so that there isn't a need for erosion-causing mechanical plowing to take care of weeds in the vine rows. Tillage is still the main option for Organic growers. So, in all these cases the EU's pesticides and organic goals are in conflict with one another when it comes to that iconic industry

 

As mentioned earlier, there are several wild grape species that are more resistant to powdery and downy mildew. Theoretically traditional breeding methods could be used to transfer some of those genes. Conventional breeding of grapes is possible but slow, and it has been used to develop things like seedless table grapes with new colors and flavors.  Some new wine grape varieties with disease resistance from wild grapes have been developed by breeders working for the University of California, and they were repeatedly "back-crossed" so that the final result was a variety with 95% vinifera genes. But because of tradition and some remaining wine quality questions, almost all the wine grapes of that state and other grape growing regions around the world are still the traditional European varieties.

 

With modern genetic technologies it is now possible to work with only one or a few genes from the wild grape species that confer pest resistance and do so without any effect on the thousands of other genes in the storied cultivars. This sort of precision is now much more feasible because of the genome editing technologies that are generating excitement for many applications in both medicine and agriculture.  But the EU as a whole has been very resistant to accepting "GMOs" methods even though their own scientists have long argued that such changes do not represent any greater risk to public health or the environment than do traditional means of breeding. Scientists at Rutgers University and with the USDA are working now on using this approach to get downy mildew resistance into Chardonnay. 

 

There is some hope in the scientific community that European activists and political authorities will take the logical step of saying that they can consider these modern genome editing technologies differently from how they responded to first generation genetic engineering methods. There is at least a promising mention of such technologies in the EU's Farm to Fork Strategy

 

"In response to the request of Member States, the Commission is carrying out a study which will look at the potential of new genomic techniques to improve sustainability along the food supply chain."

 

Some are even optimistic that traditionally anti-GMO groups will make a distinction for the new methods. Ideally the EU might take reasonable approach of combing state of the art genetics with the sort of low hazard synthetic chemical options that would still be important in order to avoid selecting for fungal resistance to traits a grower would need to last for decades in a new vineyard planting.  That would also relieve the wine industries in other countries from having to cater to EU trade barriers in the choices they make about how to produce their crops.

 

Europeans are not likely to abandon their taste for wine and they don't have to in order to pursue their legitimate goals.  Organic isn't the solution here.  Instead what is needed is respect for the science and more effective communication of the actual safety story behind modern agriculture.  There is an excellent explanation written by the European Food Safety Authority (EFSA) that describes how robust the approval system is for safe pesticide standards, and this is confirmed by academic experts as well. But all too often in Europe, politics trumps science. Let's hope we might someday raise a toast to a more constructive and science-driven solution to the EU's grape quandary.

My comments to the USDA about de-regulation of a transgenic, disease resistant line of American Chestnut

The kind of tree that was once abundant in the US (Wikimedia commons)

For years, public sector scientists have been working on a remedy for the disease-related near extinction of the American Chestnut which was once the dominant large tree in the forests of the Apalacian mountains.  I've heard updates about this over the years at "biotech bootcamp" events and I admire the patience and resolve that they have demonstrated in this ambitious effort.  Here is what I wrote to the agency:

Submitted Sunday 8/23 tracking # 1k4-9ijy-kaf2

 

I am writing in support of the petition for deregulated status for a transgenic American Chestnut event which has been submitted by the State University of New York College of Environmental Science and Forestry. This submission is the culmination of a long-term effort to develop a means by which this key forest species could be restored to its historical role in the forest ecosystems of Eastern North America -  a role that has been seriously compromised since the accidental introduction of a fungus which is a deadly pathogen of Chestnuts.  Although it will certainly take a long time to re-establish such a long-lived species, this strategy is the best hope we have of  achieving that very desirable environmental outcome.

 

My graduate training was in the field of plant pathology at UC Davis in the late 1970s and early 80s, so I can appreciate the challenge of counteracting this disease of this in natural forest settings. Since that time, I have also had the opportunity to closely follow progress in the science of plant biotechnology in both academic and commercial research.  The decades of experience that now exist concerning the safe and beneficial applications of transgenic technology in global agriculture demonstrate that broad deployment of this advance in a forestry setting is also something that can proceed without any undesirable or unmanageable outcomes.  Indeed, as other commenters have noted, reestablishment of this species could be expected to contribute significantly to carbon sequestration and thus help to address climate change. (see https://pubag.nal.usda.gov/catalog/757823). This sort of solution also needs to be considered for other cases where introduced exotic pests compromise the health of our forests ( see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6680343/)

 

It is significant that this project has been carried out by non-commercial entities simply focused on environmental goals. As an indicator of that, the event in question ("Darling 58") was never patented. The plan has always been to make that and related lines available for free for backcrossing into lines from multiple public Chestnut breeding and restoration efforts.  Many of the other comments that have been submitted to APHIS about this petition are from those researchers who are awaiting the opportunity to be involved in those next steps.

 

The gene that was chosen for insertion into chestnuts is for the very commonly occurring enzyme Oxalate Oxidase or "OxO."  It has always been a part of the plant genome and the human diet so there are no anticipated problems if it is expressed in reintroduced trees. The enzyme is not fungicidal itself but rather detoxifies a chemical that the fungus produces to weaken the Chestnut tree's defense mechanisms.  That kind of trait is less likely to select for resistance, something that is very important since re-establishment will be a long-term project. It is also logical that the trait will be backcrossed into many Chestnut lines to insure sufficient genetic diversity since this species will face the need for adaptation to climate change and other challenges.

 

In the absence of negative outcomes from decades of plant biotechnology, the main objection to projects such as this tends to be based on the "precautionary principle" - the idea that there is no proof that nothing undesirable could ever occur.  As such, that objection fails to consider the consequences on not employing the technology.   In this case inaction would mean that important forest ecosystems will continue to lack the natural "keystone species" which is so important for the wildlife to thrive as it once did in these areas.  The objection to human intervention in a natural system is also flawed in that human activity has already occurred with the introduction of that destructive pest.  Indeed, it makes sense to employ the best solutions available to us as humans who strive to be good stewards of our environment. The deregulation of this transgenic event by APHIS is an excellent next step towards that goal.

 

Three Foods I Wish I Could Buy At Costco

A typical Costco store front, image STU PENDOUSMAT

(This article was originally posted on Forbes on 8/6/19)

I enjoy shopping at Costco. I’ve been a member since the days when it was called Price Club. I like the diverse and yet selective range of products they offer and of course their reasonable prices. I find the staff friendly and helpful and I appreciate the fact that the employees must be treated fairly since so many are the same folks I’ve seen working there for years. The food court is an awesome deal and I almost always get my gas at Costco because it is the lowest price option in the area.  The free sample thing is fun and sometimes educational. The store is well lighted, and its aisles are uncluttered. Their wine selection is great, and Costco is where I always get my eye exams and glasses.

Cool room image from Yelp by Greg M. Used with permission. 

I particularly appreciate the way that they keep much of their fresh produce in a walk-in cold room. Yes, it’s a bit uncomfortable, but by keeping these foods cold until sale, they are extending the shelf-life for the consumer and thus reducing food waste. Yes, the packages of produce they sell are large, but I can share them with friends and neighbors in cases where I can’t get through the whole amount in time. I think it is really cool that Costco uses the empty boxes from their produce shipments to package up a customer’s purchases to take home. It is also my understanding that Costco negotiates reasonable, long-term supply contracts with the grower/shippers who supply their fruits and vegetables. Treating farmers well is a big plus on my list.   

So, you can see that there is a lot that I like about Costco. But there are three specific food items I would really like to be able to buy there but it seems unlikely that they will become available. This is because, like many retailers, Costco does not want to wade into the controversy surrounding genetically engineered foods, commonly called “GMOs.” As a scientist who has been watching the advances in molecular genetics since 1976, I find it tragic that the opponents of this method of plant improvement have been so successful in suppressing even the most logical applications for food. In many cases the losers here are that small minority in our society that still feeds us. The even greater tragedy is the extent to which those groups have blocked even free, improved crops for farmers in the developing world. But there are three specific foods I’d like to talk about which have been specifically modified for the benefit of consumers and which have actually made it through the tortuous regulatory process that the crop biotech industry self-imposed well before the first commercial plantings of biotech crops of the mid 90s. Overall, I think of Costco as a rationally, ethically run business that values its customers and respects their intelligence. Carrying these three foods would be a great way to demonstrate that respect. 

Product 1: Arctic® Apples

Arctic Granny on the left still white while ordinary apple has started browning losing flavor, aroma and vitamins

USED WITH PERMISSION OF OSF

A seven employee, farmer-founded business in British Columbia called Okanagan Specialty Fruits (OSF) developed apples that don’t turn brown when cut or bruised. They did this by simply turning off the gene for the enzyme called Polyphenol Oxidase which is what causes the browning and also degrades things like vitamins in the process. The patent they needed to license to do this was from CSIRO, a government sponsored research organization in Australia. Some plants, especially those in the nightshade family, have that same enzyme as part of their pest defense, but it isn’t really needed for the human-tended and already quite “genetically modified” versions of those species. OSF was acquired by the brave, diversified biotech company, Intrexon in 2015 and they began commercial production of the apples in 2015, launching in test markets in the Midwest in 2017. It takes several years for new orchards to come into production, but as of today there are around 1,235 acres of several varieties being grown in the US and in Canada (Arctic® Grannys, Arctic® Goldens, and Arctic®Fujis). These apples are being sold in some grocery chains in the U.S. I once met all 7 of those employees (the company has now grown to 27) during their research phase and they mailed me a box of the apples back in 2014. They were really cool! You can cut them even as much as several hours before you eat them, and they still taste and smell like a freshly cut apple. You can keep apples from browning with something like citric acid, but that changes the taste and smell. Imagine slicing these for the kid’s lunch, bringing sliced apples to a potluck or getting them at a salad bar. These apples can also be dried without the need for sulfites so that the taste is not compromised and they are not problematic for people with an allergic response to that preservative. Costco – would you please start offering these apple products among your apple options? At least at my Carlsbad, CA Costco you only offer 2 or 3 non-organic choices of apple cultivars not including my favorites. I reluctantly deal with that limitation, but don’t your customers that care a lot about food waste and flavor also deserve the choices they would prefer?

Product 2: Innate® White Russet™ Potatoes

An agricultural supply and potato processing company called Simplot has a relatively small biotech subsidiary called Simplot Plant Sciences. They developed non-browning potatoes turning off the same gene as is in the Arctic® Apples – PPO. In addition, using all genetic material from potatoes (“cisgenic”), they reduced the amount of the amino acid asparagine which can be converted to acrylamide – a possible carcinogen - during frying. They also worked with the Sainsbury Laboratory in the UK and the 2Blades Foundation to move some disease resistance genes from inedible, wild potatoes into commercially relevant cultivars. This is a really good thing for the potato growers because they have to spend far less time, fuel and money on fungicide sprays to control “Late Blight”, the disease that caused the Irish Potato Famine. This would have been extremely difficult to do with conventional breeding because potatoes very rarely reproduce through seeds. Back in 2016 I was gifted with a bag of these potatoes by Simplot. I put up a video of making hash browns with these and with regular potatoes. With the White Russets™ I was able to grate them and take my time forming them into nice shapes and to fry them without any of the browning that is normally unavoidable. They came out nicer looking and crispier. My conclusion was that these potatoes could “make America grate again.”

So, these non-browning produce options are much better in terms of the sensory experience, but they also help to reduce food waste throughout the supply chain and at the consumer level. 

The many sustainability advantages of Innate non-browning potatoes

GRAPHIC USED WITH PERMISSION OF SIMPLOT BIOSCIENCES

Today making a non-browning crop is even easier using something like CRISPR technology and the USDA has concluded that it isn’t even something that needs to be regulated. People have been working on non-browning mushrooms, and they should totally work on non-browning versions of bananas, lettuce and avocados! A way to reduce food waste and give customers a better sensory experience sounds like a good thing for a Costco to offer. Costco: could we please get these options at your stores?

Product 3: AquaAdvantage® Salmon

Costco is a major marketer of salmon in the US and they do a great job of that. Salmon is a delicious fish and a healthy option for consumers. But there is an even healthier and more environmentally desirable kind of salmon Costco could be selling in the near future. A small company in Canada licensed a technology from the University of Toronto and the Memorial University of Newfoundland in 1996 (That’s a very innovative country, eh?). It was a genetically engineered a line of Atlantic Salmon with a growth-related gene from chinook salmon and a promoter from Ocean Pout, that allows these fish to grow far faster and with less need for food. These improved fish can gain a pound of weight from a pound fish feed making them 10 times as efficient as some wild-caught fish.

Comparing the Feed-Use-Efficiency of various meats

IMAGE FROM MARINE HARVEST, 2016. (Other sources say that the conversion rate for cattle is 6:1 and of course these and other ruminants give humans access to the huge energy supply in the form of cellulose and make millions of acres of pasture land not suitable for crops a usable resource for the production of human food)

These AquAdvantage® Salmon are raised in inland aquaculture tanks and only sterile female fish are in the tanks so in the extremely unlikely case that they escaped to the ocean they would not have any effect on wild fish populations.

What one of the terrestrial fish-raising tank looks like

PHOTO FROM AQUABOUNTY VIA GENETIC LITERACY PROJECT

This multi-layered safety protocol has been scrutinized by regulators in the US and Canada over many years resulting in FDA approval in November of 2015 and the final approval for commercial sale in Canada in 2016. 4.5 tonnes were sold in the second quarter of 2018. The first US production site opened this year in Indiana. Ideally more sites can be placed near other population centers to minimize energy use for shipping. The terrestrial production eliminates issues of water pollution sometimes associated with ocean “farmed” salmon, “wild-caught salmon” or true oceanic fishing sources. The entire salmon industry has been shifting away from fish meal and fish oil for feed and these Salmon will be at the cutting edge of that trend. By sourcing from the crop Camelina or using yeasts, both of which have been modified to produce the healthy health-promoting omega-3 fats, and even the astaxanthin pigment that gives salmon its red color. There are also some efforts to raise insects to feed to the fish.  These land-based sources can allow many more people to improve their diet without putting more stress on ocean resources. The other upside is that by using these feeds it is possible to avoid the mercury and microplastics issues that are unavoidable in ocean water. These pollutants can “bioaccumulate” in the ocean food chain having gotten there because of littering and from coal-powered electricity generation.

This is all a great example of Ecomodernism – the philosophy that technology can be a means of achieving environmental goals. Doesn’t this seem like the sort of “green,” healthy option that a company like Costco ought to be offering their customers?

If Costco would rise above the threats from anti-GMO groups and offer these options alongside of “conventional” or “organic,” I believe that there would be lots of scientists like me who would happily volunteer to come in and answer customer questions during a launch program at one of those sample carts we so often enjoy at the stores.

(Disclaimer: although I know scientists and businesspeople from all of these companies, writing this article was just something that I wanted to do and not anything they asked me to do or for which I was compensated. This article was also not written on behalf of the non-profit CropLife Foundation for which I work part time recording a podcast.)

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.