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Sunday, December 29, 2013

Five Ways Farmers Control Pests Other Than With Pesticides

There are many pests in the world which attack plants or compete with them for the resources they need to grow.  This is true for plants growing in natural stands, but also for the plants that people grow as crops.  If pests are left unchecked, crop productivity is compromised. Without good pest control, it would take a lot more land to feed humanity - land we simply don't have.  Pest damage can also compromise the storage or shelf-life of foods leading to more wasteful inefficiencies.  Pests can also make foods dangerous through the production of mycotoxins (see contaminated corn below)
Corn infected with Aspergillus flavus can be contaminated
with one of the more toxic and carcinogenic chemicals known

One way that farmers prevent these problems is with the use of pesticides, and this is true in both organic and conventional production systems.   However; farmers also control pests in many ways other than using pesticides.  These tools and strategies differ based on the crop and the geography where it is grown, but they include at least the following five categories:

  1. Avoiding the pest
  2. Finding genetic resistance
  3. Modifying the climate
  4. Disrupting the pest's life cycle
  5. Fostering beneficial organisms 

1. Avoiding The Pest

Not all pests occur in all places.  Pests like insects and diseases have co-evolved with the plant species that they are able to attack, often in the geography where the crop was first domesticated.  Sometimes by moving the crop to a new location, the pest can be avoided.  This happened several times with coffee rust and with potato late blight when that crop was first brought to Europe from S. America.  Eventually the pest tends to catch up, and with the intensity of modern travel, pest redistribution is inevitable.  The more stable way to avoid a pest is to grow the crop in a new climate that does not favor the pest.  When fruit and vegetable crops are grown in Mediterranean climates (e.g. California, Italy, Spain...) where there is little or no rain in the growing season, many diseases are avoided.  This of course requires irrigation, but if that is done with subsurface drip, weed growth is also largely avoided (see below).

Another good example is the potato industry which is in the San Louis Valley of Colorado surrounded by high mountains.  This isolates the crop from aphids and the viruses they spread and is particularly good for seed potato production.

2.  Finding Genetic Resistance

Wheat stem rust is a potentially devastating disease that was successfully
controlled using genetic resistance for several decades

One of the reasons for a concerted effort to maintain extensive seed banks is to maintain the genetic diversity in a crop which may include resistance traits to various pests.  For instance, when the resistance to wheat stem rust was finally overcome by the UG99 strain of that fungus, wheat breeders went to the seed banks to find a new resistance gene and have been cooperating internationally to get that trait bred into the myriad types of wheat grown around the world.  There are also often genetic solutions for soil-borne pests which involve grafting the desirable type of a fruit or vegetable onto a rootstock that provides resistance.  This is most commonly used for perennial crops, but in recent times this sort of grafting for genetic resistance is also being used with tomatoes, cucumbers and even eggplants.

Genetic engineering provides a means of using genetic pest resistance in situations where ordinary breeding for such a trait is either impossible or far too slow.  For instance there is a gene for resistance to a bacterial disease of peppers which has been moved to tomatoes making them resistant to that same bacterium.  Potatoes are difficult to breed, but by transferring a gene from wild potatoes from the Andes, disease resistance has been moved into modern, commercial-type potatoes (see below).
Potatoes genetically engineered to resist late blight
using a gene from their wild relatives

Breeding resistance to coffee rust is possible, but doing that with conventional breeding methods will not be fast enough to help the small-holder coffee farmers whose way of life is now threatened by that disease.  Unfortunately, the rich world part of the coffee industry has elected not to use genetic engineering to speed up that process.

3.  Modifying The Climate

Wine grape growers often use trellising methods and removal of lower leaves to change the microclimate where the grape clusters are developing.  This helps to prevent a fungal disease called "Botrytis bunch rot."   There are a whole range of growing practices called "protected culture" that range from a simple rain shield to a passive greenhouse to a high-tech greenhouse with complete climate control.  These measures provide relief from certain diseases that would otherwise be fostered by rain.  In some cases the system excludes insect pests all together (see below).  Although this approach is too capital-intensive for many crops, it is very effective for high value vegetable and fruit crops and this is a rapidly growing segment of agriculture around the world.
Tomatoes grown without soil and protected from insect pests

4.  Disrupting The Pest's Life Cycle

Perhaps the most common way that pests are controlled in annual crops is through the use of crop rotation.  For instance, corn is typically rotated with soybeans throughout much of the midwestern US.  This prevents population increases of certain pests because every other year certain pests don't have a suitable host available.  For potatoes it is often necessary to have several seasons of other crops planted between each potato crop, otherwise pests become too damaging.  Another way that insect pests can be controlled is through an approach called Mating Disruption.

Synthetic versions of the insect's mating hormones are placed throughout a field or orchard so that the males can't detect the gradient of that hormone which guides them to females.

In certain cases it is possible to release large numbers of male insects which have been intentionally raised and sterilized.  These males then out-compete the wild ones to mate with the females and so very few offspring are generated within the population.  For pests that are quite specific to a given crop and which don't succeed on other crops or weeds, it is possible to organize a time of year when no examples of that crop are growing throughout a given geographical area.  The crop-free period results in a crash in the pest population.

5.  Fostering Beneficial Organisms

Even pests have pests, and often there is a way to encourage those "natural enemies" sufficiently to keep crop pest populations at tolerable levels.  For example, the cottony cushion scale was once a big problem in the California citrus industry, but the problem was greatly reduced once a natural predator of the scale called the Vidalea Beetle was introduced into the state.
Cottony Cushion Scale

Vedalia beetle

The grape leafhopper can be a very damaging pest, but when growers plant wild blackberry vines near their vineyards, they encourage the build-up of a certain kind of parasitic wasp which attacks the blackberry leafhopper species in addition to the grape leafhopper.  This can keep the grape leafhopper numbers sufficiently low to make pesticidal control unnecessary.  Some insect predators or parasitoids are raised commercially for release on farms.  Some diseases and nematodes are controlled by applying biocontrol agents such as bacteria or fungi which act as hyperparasites.   When potatoes were genetically engineered with a Bt protein to resist the Colorado Potato Beetle, farmers noted that secondary pests were no longer a problem because the natural enemies were no longer being killed by broader spectrum insecticides.  Unfortunately, when fast food companies chose to use their leverage to end the growing of Bt potatoes, a resurgence of these secondary pests was one of the consequences.

Pest control in agriculture is a multi-dimensional effort, and pesticides are just one of the important tools, procedures and choices that farmers employ.  Some of these tools have been in use for a very long time and some are new.  With climate change, the control of pests will become even more difficult. As global population grows and standards of living increase, it will be even more important for farmers to avoid the sort of losses and food waste than can be caused by pests.  Fortunately the tool box available is diverse and constantly improving.

You are welcome to comment here and/or to email me at

Image of corn with aflatoxin-producing Aspergillus flavus infection from Iowa State University IPM
Drip irrigated tomato image from
Wheat stem rust images from USDA-ARS
Grafted tomato image from Wikimedia Commons
Engineered blight resistant potato image from The Sainsbury Laboratory
Vertically trellised grapevines with leaf removal image from
High tech tomato greenhouse image from Wikimedia
Mating disruption graphic from WSU Tree Fruit Research and Extension Center
Cottony Cushion Scale image from
Vedalia beetle image from Wikipedia

Tuesday, November 19, 2013

What Trans-fats Should Teach Us About The Pitfalls of Food Labeling

On November 7th, the FDA announced that it will remove partially hydrogenated oils from the GRAS list (Generally Regarded As Safe).  These oils contain trans-fats.  The agency has concluded that the voluntary replacement of such fats has not progressed far enough to adequately protect Americans from the negative cardiac health dangers that they pose. This is a good, if seriously belated, decision. It is worth looking back at the history of this food ingredient to see how we came to be eating trans-fats in the first place and what role food labeling (mandatory and marketing) played in that story.

The Origins Of The Low Fat Diet Push

In the 1960s, medical and public health officials became alarmed at the high rates of cardiac-related sickness and deaths in the American population.  A correlation was found with high-fat diets and soon there was widespread advice to avoid two particular categories of fat – cholesterol and saturated fats. In retrospect this was a severe over-simplification and a demonstration that correlation does not mean causation. Unfortunately a “low fat diet” caught on as “the answer” with the public and with food marketers. More and more food products entered the market with voluntary labels such as “Low Fat,” “Cholesterol-Free,” “Zero Fat,” and “Low in Saturated Fat." This trend didn’t turn out to be health-promoting. In many foods with lowered fat content, additional sugar was added to make it more palatable. For many years, eggs were demonized because of their cholesterol content when in fact they are an excellent and reasonably priced protein source. All the decades of focus on avoiding fats or certain fats did nothing to stem the obesity epidemic, and reductions we do see in heart attacks and strokes are thus probably linked to other factors.

How Misguided Food Labeling Led To Our Consumption Of Trans-Fats

When the negative focus on fats began, animal fats were major sources of cholesterol and saturated fat in our diets (butter, lard, bacon fat).  Tropical oils, such as palm and coconut, were additional sources of saturated fats. The pressure to find alternatives to these oils coincided with an increasingly abundant supply of oil from the domestic soybean crop.  Soybeans were a minor US crop before World War II, but by the 1970s they had become the major source of protein for animal feeds. A soybean contains ~20% oil and so it rapidly became the lowest-cost oil in the American food supply. 

Soy's Limitations

There are, however, issues with soybean oil. It has properties that make it unsuitable as a simple substitute for animal and tropical fats in various applications (if you are interested there is a short course on the chemistry of oils and fats at the end of this post). It couldn’t be used to make a substitute for stick butter because it was liquid at room temperature.  Soybean oil was also poorly suited for deep fat frying applications because it didn’t have the necessary “fry life” to fit in the burgeoning fast-food industry of that time.  After a relatively short period of high temperature cooking, it would develop off-tastes.  In other products it tended to turn rancid faster that other alternatives.

Food scientists had earlier developed “partial hydrogenation," a process through which most of those issues could be addressed (hydrogenated oils began to be sold early in the 20th century).  Hydrogenation allowed food companies to turn soybean oil into margarine and then to market it against butter as a perceived healthier option.  In the anti-fat environment, oil processors could sell partially hydrogenated oil to the fast food industry, which then promoted the supposed health advantages of their switch to “vegetable oil.”  The converted oils were also extensively marketed in products with the marketing claim, “No Tropical Oils.”  This was somewhat of an intended health claim, and also a means of competing with the low cost imported oils from palm and coconut. The hydrogenated oil also had some unique properties which were particularly useful for certain baked goods.

Between low cost and these positive-sounding messages, hydrogenated soybean oil found its way into a host of foods in the US diet. When mandatory nutrient content labeling was established in 1990, Congress failed to fund the education component envisioned in the bill.  Thus, the official "back label" only served to further propel the sales of various fat-avoidance products and trans-fats, and did nothing to stem the disinformation on the front, marketing-oriented labels.

Early on,  the substitutions being made by these commercial entities were done with confidence that they were a good thing. Unfortunately, that was not true. 

The Solution Becomes The Problem

Unfortunately, during the hydrogenation process “trans” versions of certain fats are generated.  The term trans has to do with a specific chemical configuration in the fat molecule.  In most oils and fats that configuration is generally of the “cis” configuration and rarely the “trans” (again, more details below).  It was this subtle difference which was later found to change the way that these fats functioned in our bodies.  Most of the fat we eat is simply converted to energy, but some is incorporated in the membranes that surround each of our cells.  Some of the fat can also end up in plaque deposited in our veins and arteries.  The health issues for trans-fats played out importantly in those functions.

In retrospect, Americans would have been much better served in terms of flavor and health if they had stuck with the animal fats and tropical oils instead of hydrogenated oils (French fries have never been as delicious as when they were cooked in beef tallow!)

Eventually, evidence began to emerge that trans-fats were problematic for human health when consumed in larger quantities. This only very slowly built up to the point where regulators raised red flags and began to require trans-fat labeling in 2006.  Many food companies shifted away from trans-fats and to market foods as having "zero transfat." Now the FDA is finally moving to fully eliminate an undesirable ingredient which became common because of earlier labeling trends.

What Should We Learn From This?

So, did we learn from the low fat marketing experience?  Seemingly not much.  Instead we have continued down the path of magical thinking about food.  We go through fad after fad about what single bad actor ingredient to avoid or what magical good component to eat, somehow believing that these simplistic formulas can put us on the path to health.  The press, various celebrities and "experts" are often guilty of over-selling such ideas as they emerge incompletely formed from the fields of nutrition or medicine. Well-meaning or simply opportunistic food marketers are then more than willing to follow or even promote each fad.  I call that "the marketing of non-existance." We continue to be sold new non-existence options such as  “Low Carb,” “no High Fructose Corn Syrup,” “Gluten-Free,” and “non-GMO.” These are dietary strategies based on the mindset that foods are something to be feared or at least viewed with suspicion.  

These fads distract us from the fundamental healthy diet principles of moderation and diversity.  They distract us from the fact that the most dramatic way that most Americans could improve their health prospects would be to consume more fruits and vegetables.  Perhaps its time to start buying what we eat for what it is as a whole food, not for what it is not.

You are welcome to comment here and/or to email me at  I tweet about new posts @grapedoc

A Short Course About Oils And Fats

Fats and oils are similar with fats being solids at room temperature and oils being liquid.  In both cases they consist of triglycerides - three "fatty acids" connected to a glycerol backbone.

What makes the various fats and oils different from one another is what kind of fatty acids they contain.Fatty   acids are chains of carbon atoms with a polar carbonyl group at one end.  They differ in the length of the chain and in how many double bonds there are between the carbons.   

As shown above, the dominant fatty acid in animal fats is stearic acid with 18 carbons and no double bonds (saturated).  Oleic acid which is a major component of olive oil or modern Canola and Sunflower oil also has 18 carbons, but has one double bond (mono-unsaturated).  Linolenic acid was one of the problematic components of soybean oil which needed to be fixed by partial hydrogenation.  It has 18 carbons and three double bonds (poly-unsaturated).   "Tropical oils" are generally shorter chained - Palm oil has mostly 14 carbon amino acids and coconut oil has mostly chains of 12 carbons.

The cis- and trans- fats differ in the orientation of the hydrogen atoms (white) attached to the carbon atoms (black) that are connected by a double bond.  The normal cis- configuration has both hydrogens on the same side of the chain.  The trans- configuration has the hydrogens on the opposite side of the chain and this gives the fatty acid a different bend and influences its fluid properties when it is part of a membrane.  There are some natural trans-fats, particularly in meat and milk from ruminants because rumen bacteria convert unsaturated fats to saturated forms, going through some trans- intermediates along the way.  There are actually health benefits associated with the production of Conjugated Linoleic Acid (CLA) in this process.

Thursday, November 14, 2013

My Comment To The USDA In Support Of Deregulation Of The Arctic Apple

I would like to express my strong support for the deregulation of the non-browning apples developed by Okanagan Specialty Fruits, Inc.  As a consumer I would very much like to have the choice of buying apples which would maintain their appearance, taste and nutrient content longer after being cut.  As a long-term agricultural scientist I completely agree with the USDA's assessment that these apples are not any sort of plant pest. 

Since apples are not grown from seed, but rather propagated by grafting and other clonal means, any minor cross-pollination between blocks of modified and non-modified apples is functionally a non-issue.  Different varieties of apples are routinely planted side-by-side with no concerns about "contamination." 

I know that the issue of organic certification has been raised, but there is no rational reason why that should be a concern.  The precedent for the unintentional presence of unapproved pesticide residues on organic fruit is that even if it occurs it does not effect the certification of the farm in question.  If that is the logic for residues that may be consumed, then the logic should prevail for the presence a few, down-regulated genes in a small number of cells in the germ of a seed.  This is particularly true because the seed is not consumed (apple seeds are cyanogenic so it wouldn't even be a good idea to eat them if someone wanted to).

Consumers should get to decide whether they are interested in this trait.  They will have that choice because it will be marketed explicitly as an improvement via genetic engineering.  This is an optional trait, but it is a key test of whether our regulatory system and commercial channels will stick with a science-based approach or yield to activist political and brand pressure tactics.  There are other traits coming such as resistance to citrus greening which may be critical for the survival of a crop industry, and what happens with the Arctic Apple could effect the chances of that solution becoming available to farmers.

I realize that there has been some opposition to the Arctic Apple from apple industry organizations - not because of any plant pest or consumer safety concerns, but because of "brand risk."  I think the broader apple industry would do well to remember that for a long time they tried to build an "apple brand" based on an intentionally narrow group of varieties - Red Delicious being the primary standard based on color and shape more than on flavor.  When that strategy collapsed in the wake of the "Alar Scare," innovative growers branched out and began offering consumers a wide range of varieties with different appearance and flavor.  It turned out to be an extremely healthy shift that strengthened the "apple brand" among consumers.  Adding non-browning options for consumers to choose is a continuation of that successful marketing strategy.  

You are welcome to comment here and/or to email me at  I tweet about new posts @grapdoc


Monday, October 7, 2013

The People Side Of GMO Crops: Part I

As with any new technology, the development and commercialization of biotech crops is a story about people.  Its a story about people with ideas and vision; people who did hard and creative work; people who took career or business risks, and people who integrated this new technology into the complex business of farming.  By various artifacts of my educational and career path, I've been in a position to know many of these people as friends and colleagues over the last 36 years.  Their story is important, but it tends to get lost in much of the conversation about biotech crops.

Many narratives about "GMOs" leave out the people side, presenting it instead as some faceless, monolithic phenomenon devoid of human inspiration, intention and influence. Thats not how it happened.  Other narratives about "GMOs" demonize those who made biotech crops a reality. Such portrayals are neither fair or accurate.  The real stories of these people matter, because trust in a technology is greatly influenced by what people believe about those behind it.

That is why I'd like to write about what I have observed about these real and trust-worthypeople over the years. I'll start with the period 1976-1982.

It Started On "The Farm"

Stanford has the nickname, "the farm" but its no Ag School!

I first heard of genetic engineering in 1976 while a senior at Stanford University in a graduate level biochemistry class. The professors lecturing on the exciting new science of molecular biology were Paul Berg, Stanley Cohen and Herbert Boyer.  These basic researchers were doing purely lab work with no commercial motivation, but in the process, they ended up inventing "recombinant DNA technology." At the point of my introduction, the science was still young (key experiments started in 1971).  The Stanford researchers discovered the enzymatic "tools" to cut and paste genes and other key pieces of DNA.  From the beginning it was clear that these discoveries had a huge range of potential applications in basic research, medicine, pharmaceuticals, bio-materials and bio-processing.  It also had potential for agriculture. It was an exciting time, but it took many years for all this to unfold in practical applications.  Berg later received the Nobel Prize for his work and the patents that came from the work of Cohen and Boyer became some of the most widely licensed in history (they became a huge source of research dollars for Stanford).  Genetic engineering, GMO if you will, started in the labs of people who were focused on academic research.

Safety First

The setting for the first conference on biotech safety

It is significant to note that these and other early genetic engineering researchers took special precautions from the very beginning to make sure that they were not creating something in their labs which could be dangerous.  Paul Berg was instrumental in organizing the 1975 Asilomar Conference, a gathering of scientists designed to carefully consider all the ramifications of this new science of "genetic engineering." The outcome of that conference helped guide the NIH (National Institutes of Health) to set guidelines for lab safety regarding biotechnology.  The original rules were severely restrictive, and were only relaxed a bit after much experience and increased understanding.  I'd be interested whether any of my readers are aware of other technologies for which such precautions were taken at such an early a stage?  This standard of thoughtfully trying to anticipate any risks or issues carried forward as the science developed.

Off To Davis To Become An Aggie

The iconic water tower at Davis

Many biology students from my generation went on to pursue the various applications of genetic engineering.  Although I was fascinated by what I had learned about this basic science, I was interested in a much more applied science called Plant Pathology - the study of diseases of plants.  So, in 1977 I started graduate work at the University of California, Davis - an actual ag school.  My research was field oriented and I got my first exposure to farming and farmers.  However, one aspect of my project involved lab work, and the particular equipment I needed was in the adjoining labs of Dr. Robert Shepherd and Dr. Tsune Kosuge.  Both labs worked on topics which were of great importance to the brand new science of plant genetic engineering.  So, my education about biotech continued.

My lab-mates at Davis were pursing very basic research needed to answer two key questions:  "How can we get new genes into the nucleus of a plant cell?" and "How will we get those genes to express" - to be turned on in the cells of the plant as desired?  

A Virus Disease of...Cauliflower?

My little bit of bench space was in Shepherd's lab which worked on virus diseases including Turnip Mosaic and Garlic Mosaic Virus (the smell of the later often permeated the lab as samples were ground up for analysis).  The lab was also one of a few around the world that worked on CaMV (Cauliflower Mosaic Virus).  That is a rather minor disease, but it was of interest because it is a DNA plant virus while most plant viruses are RNA viruses.  Several of my lab mates were "sequencing" that virus, meaning that they were figuring out the pattern of A,T,G and C bases in its genetic code.  The methods they used are humorously crude by modern standards and it took them more than a year to get the sequence - something that would probably take less than a day with modern equipment.  In any case, there was a hope that once the genetic code of CaMV was understood, it might be possible to use that virus as a way to move a new, desired gene into a plant.  After all, the virus manages to do that for its own purposes.  That goal never materialized because the virus protein capsule was too small to "package" a useful gene, but CaMV turned out to be important for a different reason.

You can't fit much DNA in these little virus particles

A gene "promoter" is a part of the DNA sequence that sits in front of a gene and tells tells cells how and when to express that gene - usually meaning to have the cell make the protein for which it codes.  It turned out that a promoter from CaMV called "35S" eventually became the most widely used promoter for transgenic crops of the first generation - both in research and commercial use. At the time, however, the team in the Shepherd lab was just doing basic research, mainly with the hope of getting out some good publications.  35S was actually first described and patented by a group at Rockefeller University.   

Nature's Genetic Engineer

Graphic about how Agrobacterium works, now that we understand 

The neighboring lab (Dr. Kosuge's) also had equipment I needed.  The graduate students, technicians and post-docs there all worked on a soil microbe called Agrobacterium tumifaciens which causes a disease of many plants called "Crown Gall."  Agrobacterium is nature's "genetic engineer."  When it gets into a plant injury it is able to inject a circular piece of its DNA (a plasmid) into the exposed cells.  Then, the genes from the bacterium start functioning in the plant.  The bacterium "engineers" the plant to provide itself with both a protective home and an exclusive food supply based on two unique amino acids only it can use.
A crown gall on a grapevine "engineered" by Agrobacterium

Many labs were trying to figure out the details of how Agrobacterium does that, and Kosuge's group was one of them.  The goal was to "disarm" that "Ti Plasmid" so that it would no longer make the plant sick, but maintain its natural function of inserting genes. Only by understanding the detailed regions of the Ti plasmid would it be possible to only insert desirable genes.  Other approaches were being tried in other labs.  Ultimately, a tamed version of Nature's genetic engineer became the most desirable way to put new traits into a plant.   The researchers in Kosuge's lab were all just making small contributions to that ultimate development.  Many labs around the world were working on the same thing. 

The atmosphere in both of these labs was one of excitement about a distant goal of making a positive contribution to the future food supply, but it was also a group of people excited about being on the cutting edge of a field of science.  Commercial applications were a distant concept at that point.  As with those at Stanford, these researchers were concerned about making sure their work was safe.  Dr. Kosuge was instrumental in convening a major conference of "Risk Assessment in Biotechnology" that was held in Davis in 1988 and which I'll describe later.  Most of the people coming out of these labs went on to the sort of academic jobs all of us were shooting for at the time, but some moved on into the next chapter of plant biotechnology which began in the very early 1980s - the small, start-up companies.  I hope to write about that phase sometime soon.

You are welcome to comment here and/or to write me at

Image of the Stanford Quad in 1978 from Wikimedia Commons
Asilomar State Beach image from Wikipedia
UC Davis water tower image from the UC Davis website
Agrobacterium graphic from Nature
Grape crown gall image from Bill Moller of UC Davis (he was one of my advisors there)

Wednesday, September 25, 2013

Why GMO Wine Grapes Would Be Cool

Chardonnay grown in Colorado
I am 99.9% sure that there will never be commercial production of genetically engineered wine grapes ("GMO" to use the common misnomer).  Even so, I'd like to indulge in imagining what could be if we lived in some parallel universe where rational scientific thinking prevailed.

Wine grapes are an extremely logical crop for genetic engineering because there is no tolerance for changing varieties. For annual crops like grains or vegetables, new varieties are bred on a regular basis to solve pest issues or to improve features like taste or shelf life. Breeding of perennial fruit crops is a much, much slower process, but entirely new varieties are still introduced from time to time (e.g. Jazz or Pink Lady apples).  Even what we call "heirloom varieties" of most vegetable or fruit crops are mostly quite young by wine grape standards.

Conventional breeding just isn't a viable option for wine grapes, not because it couldn't be done, but because in an industry so focused on quality and tradition, no one would consider it. The wine industry is based on specific varieties which are hundreds of years old and for which no new variety would ever be acceptable. That is true for varieties in their original appellations (e.g. Pinot Noir and Chardonnay in Burgundy or Cabernet Sauvignon and its blending partners in Bordeaux).  It is also true for those same varieties that now make great wines in "New World" (e.g. Malbec in Argentina, Zinfandel in California, or Syrah in Australia).

Therefore, wine grape varieties have been cloned for hundreds of years, specifically to avoid any genetic change (they have always been grown from rooted cuttings or from grafted buds). Grapes make seeds, but the seed won't grow up to be the same variety as the parent, thus they are never used as a way to grow new vines.

The Downside of Ancient Varieties

Of course, by sticking to very old varieties, wine grape growers must deal with many problems which might otherwise have been solved through breeding.  Grape growers have been able to deal with some pests that attack the roots by grafting onto diverse "root stocks" with novel genetics.  That was the solution to the great Phylloxera epidemic of the 19th century. But rootstocks can only help with a limited number of grape growing challenges.

Why Genetic Engineering Would Be Logical For Grapes

Biotechnology is a perfect solution for wine grape issues because it allows changes to address one specific problem without disrupting any of the characteristics that determine quality. Of course, each variety would have to be individually transformed, but in our imaginary rational universe the regulatory regime would be made easier for multiple uses of the same basic genetic construct.

So, genetic engineering could be a very cool solution for various challenges for grapes.  I'll list a few of the diseases that might be fixable this way.


Grape Downy Mildew infection on a leaf
As I described in an earlier post, the noble grapes of Europe must now be rather intensively sprayed with fungicides because a disease called Downy Mildew was introduced in the mid-1800s from New World grape species. Those same North American species have a good deal of resistance to that disease, and the genes for those traits could probably be identified and moved into the traditional, high-quality varieties.  

Grape Powdery Mildew infection of young berries
This strategy might also be employed to reduce susceptibility to another disease called Powdery Mildew which requires frequent sprays or sulfur dustings even in dry environments like that of California. There are even susceptibility differences between Vitis vinifera varieties which might be able to be moved.

Rot Reduction

Tight clustered Chardonnay is prone to rot diseases
Botrytis Bunch Rot is most problematic in grape varieties where the clusters are very "tight" (e.g. Riesling, Pinot Noir, Chardonnay, Zinfandel) and less problematic in varieties where the cluster is looser with more stem between the berries (e.g. Merlot, Cabernet Sauvignon).  It is possible to loosen up clusters with a very well-timed spray of the plant hormone gibberellic acid, but that is difficult and can affect the next year's yields.

Loose clustered Merlot is less likely to rot
If the genes which control the development of the main cluster stem (rachis) could be identified, it would be possible to make less rot-prone versions of great varieties and thus reduce the amount of waste caused by Botrytis.

Fall symptoms of Leafroll virus infection

Viral Diseases

Viral diseases of grapes, spread by insects, can shorten the productive life of a given vineyard planting. If you tour grape growing regions in the fall you may see vines with leaves that have turned red. It's sort of pretty, but it means that those vines are infected with Leafroll Virus - spread by mealy bugs.  Such vineyards bear progressively less fruit and fruit of lower quality until the point at which it becomes necessary to tear out those vines and re-plant - often years before it would otherwise be necessary.  A transgenic solution to that virus is definitely possible as it was with a virus that nearly destroyed the Hawaiian Papaya Industry. 

Pierce's Disease - A Potentially Existential Threat

Grapes are also susceptible to a disease which actually kills the entire vine.  The pathogen is bacteria-like and is endemic to various riparian plants in the US.  If an insect vector happens to move from those plants to a vineyard, it can lead to an infection called Pierce's Disease which will soon destroy the vine. In the Southeastern US this pathogen makes it impossible to grow the European grape varieties.  In California infections were known, but were relatively rare because the native vector (the bluegreen sharpshooter) didn't tend to move very far into a vineyard.  Then in the 1994, a new vector called the Glassy Winged Sharpshooter was introduced into Southern California and started vectoring Pierce's disease into vineyards on a large scale.  For a while it looked like this new combination would be the sort of existential threat now facing the Florida Orange industry.  Fortunately, growers learned how to check the population of the vector by spraying it when it was in neighboring citrus groves, before it moved to the grapes.  Also, it appears that some degree of natural biocontrol has kicked-in to keep the overall population of glassy winged sharpshooters manageable.  Should this disease become a major problem in the future, a genetic engineering solution might be the only viable solution.

Voluntary "GMO labeling" Would Be Easy for Wine

Because wine grapes can be extremely valuable (e.g. as much as $10-20,000/acre), and because quality is closely connected with the location where they are grown,  "identity preservation" is common in the industry. It would be entirely feasible for grapes which were or were not "GMO" to be kept separate to what ever extent was desired.  So, one winery could proudly label their wine as "improved via biotechnology to provide disease resistance," while the neighboring winery could confidently claim not to be "non-GMO" if they so desired. Again, remember I'm talking about what could happen in a parallel universe where reason prevails. In our universe (as has already been demonstrated in both France and in Mendocino County California) reason quickly yielded to the politics of fear and unfounded concerns about "genetic contamination."

So, there will probably never be commercial "GMO grapes" in our universe, but that doesn't change the fact that it is a cool concept.

You are welcome to comment here and/or to email me at

Colorado Chardonnay image SDSavage
Grape Downy Mildew (Plasmopara viticola) image from the University of Georgia Photo Archive
Grape Powdery Mildew image from Wikipedia
Rotting Chardonnay image SDSavage
Merlot image from Naotake Murayama.  
Leafroll virus image from Oklahoma State University

Wednesday, August 28, 2013

When A Genetic Solution Saved The French Wine Industry

The mid to late 1800s was a very difficult time for the European wine grape industry.  New pests associated with native North American grape species made their way to the "Old World" because of transport between the continents.  I recently wrote about how a fungal disease called downy mildew nearly destroyed the industry until it was saved by the accidental discovery of an effective chemical fungicide.

In today's post I'm going to talk about an insect pest that was introduced to Europe in the same era.  It was a a root feeding relative of aphid called Phylloxera.  Native American grapes are quite tolerant to it, but when it started attacking the roots of the European, Vitis vinifera grapes it began debilitating and finally killing the vines.  It may have arrived in the 1850s, but was first recognized in 1863.  This was an extremely trumatic economic and social crisis.  More than 1 million hectares of vines were killed and many more debilitated before a solution was finally found. In this case the ultimate solution was found via genetics  (There are many good sources about the extended drama and real economic suffering associated with this this crisis - see links below)
1888 drawing of what is now classified as Daktulosphaira vitifoliae

The Genetic-based Technology Solution

The solution to Phylloxera that was ultimately applied seems obvious with hindsight.  Since the North American grape species had always tolerated this pest, why not use them as "rootstocks" and graft the revered European varieties on top of them?  Grafting of desired varieties onto the roots of less desirable, but either more hardy or already established versions of the same crop was not a new idea.  That had been practiced for thousands of years for many tree and vine crops.  The ancient Hebrew and Christian scriptures are full of literary images based on the concept of grafting.  It was an ancient, practical solution - but what it amounted to was a rather dramatic "genetic modification" of the roots of millions acres of European grapes (and eventually grapes around the world).

This idea of grafting onto foreign, low quality grapes was hard to swallow for much of the French wine community of the day.  Their questions included:

  • Will treasured, traditional varieties like Pinot Noir grafted on this inferior sort of grape still make a classic red Burgundy worthy of each specific appellation in that district?  
  • Will this new reality mess with the quality that was traditionally achieved with complex blend of varieties in a region like Bordeaux?
  • Will this new pest eventually overcome this solution?  
  • Should wine made from grapes grafted on American rootstocks be labeled as GMO?
Ok.  They didn't ask the last question in the 1800s, but there was a long-running and eventually meaningless debate about whether pre-Phylloxera wines were better.

An Ironic Modern Rejection of a Genetic Save for Grapes

Flash forward to modern times.  There is a nematode pest which spreads a grape disease called Fanleaf Virus.  Once the soil on a given site has been contaminated with that small, roundworm parasite and the virus, if you plant vines there, even after ten years with no grapes, after a few years they decline and die.  This is actually a problem nearly as old as Phylloxera, but fortunately it does not spread easily.  Once people understood how it works, it has been mainly limited to certain areas in France, some other European countries, and a few places in California.  The sad part is that there are significant hectares of vineyard sites in premium wine growing districts that can't be used to make great wine because of this issue.  For many crops, one can just move away from such problems, but for wine the unique combination of climate and soil can create conditions which are legitimately important for quality.  The term "Terroir" is used to describe that essence of place.  Fanleaf virus and its vector severely compromise the Terroir wherever they occur.

With the advent of biotechnology there was the possibility of a better solution for Fanleaf contaminated sites that never existed before (there were some nematode resistant rootstocks but they were undesirable for other reasons).  A rootstock was developed which was resistant to the virus using the same approach that saved the Hawaiian papaya industry.  With that genetic solution, high quality grapes could be successfully grown on on compromised sites in a way directly analogous to how American grape rootstocks saved the crop from Phylloxera in the 1800s.

One might imagine that with the tremendous esteem for terroir in the wine French wine industry, this means of rehabilitating highly valued vineyard sites would be eagerly embraced by the wine industry. Unfortunately that was not the case.  There were some modest field tests of this rootstock being conducted by a French governmental agency in 2010.  There was a great deal of public controversy about this, little industry defense, and ultimately activists destroyed those trials on August 15, 2010.  Their stated concern was that this new rootstock could "genetically contaminate" the rest of the grape crop.  Let me explain why that fear was irrational to an absurd degree:

As this post describes, back in the late 1800s, the entire French and European grape crop was replanted on American rootstocks which differ from the Vitis vinifera grapes by probably hundreds of genes or versions of genes.  No one has ever needed to worry about "genetic contamination" from those millions of acres of genetically "foreign" rootstocks even though they have been present for over 100 years.  If those industry-saving American rootstocks (which are normally only underground) ever happened to get the chance to flower and generate pollen, it still wouldn't matter because grapes are never grown from seed. They are always grown from cuttings or buds.  That is also why you can plant blocks of different grape varieties side by side with no issue of "contamination."  So why would rootstocks with ONE very useful gene inserted by genetic engineering suddenly be a contamination risk?  There was absolutely no risk!

As far as I can tell, the grape industries in France and elsewhere were sufficiently intimidated by the magnitude and ferocity of the irrational response to have decided to simply live with some of their best vineyard sites being compromised. If someone in those industries knows differently, please let me know.

You are welcome to comment here and/or to email me at  I tweet about new posts @grapedoc

grape image mine
Phylloxera drawing from Wikimedia Commons

There are many websites which describe this traumatic event for the European grape industry and for the economy as a whole (Wikipedia: Great French Wine Blight, a review of what sounds like an interesting book about this by Christy Campbell,  a nice summary from 1986 in Wine Tidings republished  by The Wampum Keeper).