Everything is chemicals: the myth and fear of “chemical-free” gardening

“Chemical-free” – a term I’ve seen several times attributed to many products, especially food and produce at farmers markets and even in gardening circles these days.  This term is often misused to describe plants grown without the use of any pesticide, either conventional or organic. I have my thoughts that I’ll share later on that subject but first let’s talk about this “chemical-free” that gardeners, farmers, and others use and why its not only a myth, but a dangerous one at that.

Ain’t such a thing as “chemical-free” anything

At face value, the term “chemical-free” would literally mean that whatever the label is applied to contains no chemicals.  That the entire item, whether it be animal, vegetable, or mineral is devoid of any and all chemicals.  Factually this can never, ever be true.  Everything that exists is made of chemicals.  Oxygen, water, carbon dioxide, and any simple molecule, by definition, is a chemical.  Plants and animals are organized structures filled with complex chemicals.  Even you and I, as humans, are walking, talking bags of chemicals.  The air we breathe, the food we eat, and the water we drink are all composed of a great mixture of chemicals.  The use of the term “chemical-free” to describe anything is uninformed at best, and intellectually dishonest at worst. But a bigger problem, as we’ll discuss later, is that using the term can cause confusion and even fear of things as simple as food and as complex as science and medicine. 

Expert reveals how even natural foods contain chemicals | Daily Mail Online
The “ingredient list” of a peach.
Source

What most people intend to say when they use the term “chemical-free” in relation to plants or produce is that they are produced without use of pesticides or conventional “chemical” fertilizers.  Therefore, a better term to use would be “pesticide-free” instead of “chemical-free” as it more accurately represents the situation.  Many may ask why the term “organic” or “organically grown” couldn’t also be used to describe “pesticide-free” plants.  And while those terms would be accurate, organic production can involve the use of organic pesticides that are derived from natural sources such as plants, bacteria, or natural minerals.  Natural sources of fertility for plants, such as composts and even soil itself, are all composed of a myriad of chemical substances.  Plants don’t differentiate between the chemicals they uptake from compost or soil and those from fertilizers.  To plants, nitrogen is nitrogen and phosphorous is phosphorous no matter where it comes from.

For some clarification on what different growing and production terms like these mean, check out this lecture I gave for the Oregon Farmers Market Association earlier this year.

While many have a strong opinion on the use of pesticides and fertilizers, I’ll state here that the use of any pesticide, organic or conventional, must follow the label on the container by law. And the use of any pesticide according to the label instructions means that the use of that pesticide should present a minimal risk to the health of the applicator, consumer, off-target species, and the environment.  And don’t use any home remedy recipes or products that aren’t labeled (or at least scientifically researched) for use as a pesticide.  In most cases these remedies aren’t effective, in some cases they can be more dangerous to human health or the environment than the pesticide they are trying to replace.  And applying them as a pesticide could also be illegal. 

Reading Pesticide Labels - Pests in the Urban Landscape - ANR Blogs
Pesticide label signal words that denote relative toxicity of a given pesticide.

Any gardener or producer, whether they use pesticides or not, should also be practicing Integrated Pest Management (IPM) to decrease or mitigate the effects of insect and disease pests on their plants.  For those using pesticides, use of the least toxic pesticide that offers control of the problem should be the last step in a series of steps to avoid damage from pests after a threshold of damage has been reached.  For those who don’t use pesticides, IPM should be a central practice in their gardening or farming practice.  Unfortunately, the tradeoff for not using pesticides is often time and labor, so successful “pesticide-free” growing often involves more work (and for produce at the market or grocery store, a higher price).  I have seen some gardeners and farmers who don’t use pesticides and don’t make an effort to practice IPM, taking whatever plants or produce mother nature and her children deal them.  I’ve sometimes referred to this type of growing as “organic by neglect” as I see insect and disease riddled produce harvested and even sold at local farmers markets.

Why does it matter?

“So what if I use the term ‘chemical-free’?  It doesn’t hurt anyone,” you may say.  While this may seem the case, the use of the term “chemical-free” has risen as a result of what many call chemophobia, effects that reach far beyond the garden or the farmers market.  This kind of thinking leads to the incorrect notion that all “natural” remedies are safe and all “synthetic” remedies are dangerous.  True, many chemicals do pose a risk to human, plant, animal, and environmental health but many do not.  Just like not all natural substances are safe.  Poison ivy, anthrax, botulinum, and cyanide are all natural and cause everything from a skin rash to instant death (sometimes I get poison ivy so bad I wish for instant death).

This chemophobia can lead to, or is a symptom of, a broader mistrust of science, the scientific process, and modern medicine that has developed in society in the last few decades.  Many attribute this to an anti-intellectual or anti-science stance in society resulting from mistrust or political saber-rattling against universities, education in general, science/scientists, “big Pharma”, “big Agriculture”, and others.  As a result, the news is filled with people who eschew well-researched scientific advances that have been proven safe and instead turn to home remedies that have no such guarantee of either effectiveness or safety.  The results can be worse than the effects of the proven advance the person was trying to avoid. 

While the outcomes of “chemical free” gardening might not have such dire consequences as immediate death, the misuse of such terms can feed into a cycle of anti-science cause and effect, serving as both a cause and a symptom of mistrust of science and the scientific process.  While everyone has a right to choose whether or not they use pesticides (or any other scientific advancement), making such decisions from a place of knowledge instead of fear is paramount for success and continued advancement. 

Sources and further reading:

https://www.columbiasciencereview.com/blog/debunking-the-myth-of-100-chemical-free-slogans

https://www.sciencedirect.com/science/article/pii/S0278691520302787

https://www.canr.msu.edu/news/chemophobia-fearing-chemicals

https://www.businessinsider.com/what-chemicals-are-in-an-all-natural-banana-2017-6

Garden Logic – understanding correlation and causation in our gardens and landscapes

This home landscape is managed using science-based methods; the only routine additions are water and arborist chip mulches.

Upon reading this post’s title, you may be inclined to stop right there. (That’s why I have an eye-catching photo to lure you in.) While logic may seem irrelevant to your enjoyment of gardening, I can guarantee that reading this blog post will challenge many seemingly logical assumptions you’ve heard or read about. Recognizing unsubstantiated assumptions and avoiding their pitfalls means you can make wise choices about how you care for your gardens and landscapes.

You can find this and thousands of other silly correlations at www.tylervigen.com

A few definitions are needed before we get started:

Correlation refers to variables whose changes mirror one another. For instance, the addition of nitrogen fertilizer to container plants is correlated to plant growth: as nitrogen levels increase so does plant growth. You can also have inverse correlation, where the variables move in opposite directions. An example is water availability in soil and planting density: the more plants you have in a specified area, the less water is in the soil.

Plant growth is correlated with increased nitrogen and other nutrients (from Xu et al. 2020)

Causation takes correlation one step further: it establishes that one of those variables is causing the change in the other. Using the same examples, we know through published evidence that the increase in nitrogen is causing the increase in plant growth, and the increase in planting density is causing the decrease in soil water because of competing roots. These relationships are obvious to us, but what’s important is that these causative effects have been established through scientific experiments.

Inverse relationship between planting density and soil water content (from Shao et al. 2018)

Sometimes scientific evidence doesn’t exist to demonstrate causation. That may be because it’s impractical or impossible to run an experiment that tests for a causative effect, or it may be because the experiments just haven’t been conducted yet. The latter is the unfortunate reality for those of us interested in managing gardens and landscapes: there is no major funding agency that supports field research for us. There is research being done, but it’s on a small scale with a shoestring budget…so the body of literature develops very slowly. In such situations, we must rely on established applied plant physiology and soil science to ask whether a suggested correlation might be elevated to causation.

Something caused these arborvitae to fail…but what? Research is slow to catch up to our observations of landscape failures.

Which brings me to my current source of online irritation: the constant blaming of tree failure on mulch volcanoes. Yes, tree failure is definitely correlated with mulch volcanoes – because lots and lots of newly planted trees fail. But is the mulch to blame? No one seems to care much that there is NO published work to show that mounds of appropriate mulch materials will somehow kill otherwise healthy trees. Instead, observers jump to the conclusion that thick layers of wood chip mulch kill trees. They are elevating correlation to causation in the absence of either experimental research OR known plant physiology. In fact, there is published research to show that thick layers of arborist wood chip mulch enhance tree establishment and survival. And there are many poor planting practices that increase the likelihood of tree failure. But it’s easiest to blame the wood chip mulch, though it’s merely masking a multitude of planting sins.

Not interested in mulch volcanoes? Well, there are lots of other examples of garden and landscape management practices or phenomena that fall into the logical fallacy camp. I’ve linked to appropriate references, when available, that go into more detail:

All of these products, practices or phenomena are correlated with some anecdotal observation (increased yield, healthier soil, plant failure, etc.) that elevates them to causative relationships. But no science.

I’d encourage you to think objectively about your closely held beliefs about your gardens or landscapes. Are you sure that what you’re doing is actually beneficial? How do you know there’s a cause-and-effect relationship? I’m not going to talk you out of your cherished beliefs – but if you are a science-based gardener, you might talk yourself out of them instead.

Willow screams in pain
What is its source of anguish?
More research needed!

SUPER Thriving Lettuce?

The Garden Professors have previously written about the ubiquitous garden center product, SUPERthrive, here and here. The manufacturer claims a plethora of beneficial uses for SUPERthrive —everything from Christmas tree care to turf to hydroponics. They claim SUPERthrive will “revive stressed plants and produce abundant yields” and that it “encourages the natural building blocks that plants make for themselves when under the best conditions” thus “fortifying growth from the inside out,” but I know of no body of rigorous, peer-reviewed literature to support any of those claims (1, 2, 3, 4). In fact, I’m not entirely sure what those claims really mean, but I’m encouraged on their website and bottle to use it on every plant, every time I water, to receive these amazing benefits!

A test case

The hydroponics claim intrigued me because during the winter months I grow plants hydroponically under lights. One of the benefits the manufacturer claims is “restores plant vigor” and “works with all hydroponics systems.” As a plant scientist, and knowing something about the ingredients, I was skeptical to say the least, but I thought that if SUPERthrive was going to show any beneficial effect it would surely be in hydroponics since that is a more uniform environment than outdoors. So, I shelled out my $11 for 2 oz (the things we do for science!) and set off to design a simple experiment.

The hypothesis

A typical experiment like this starts with what we call the null hypothesis (denoted “H0”). The null hypothesis is defined prior to the experiment and often states that we think there will be no difference between the treatment and control. In this case, my null hypothesis is that the SUPERthrive treatment will have no effect on the mean fresh weight of the harvested lettuce relative to the control lettuce. Note that I haven’t made any hypotheses about other parameters that might be important, e.g., flavor, compactness, number of leaves, color, disease incidence, survival rate, etc. For this experiment I am interested in only one thing: total harvested weight as a signifier of healthier plants.

After the data is collected and analyzed, we decide whether to accept or reject the H0 by running an appropriate statistical test. If there is no statistically significant difference, then we cannot reject the H0—that is, we accept the H0 that there is no difference between treatment and control. If there is a statistically significant difference between treatment and control, then we say we reject the H0 and conclude that the treatment did have an effect. Keep in mind, sometimes no difference between treatment and control is a good thing, e.g., in toxicity studies.

Experimental design

With my skeptical spectacles on, I set up my experiment to test my hypothesis. I made a six-gallon batch of hydroponics nutrients suitable for leafy greens. I split the batch in half and added SUPERthrive, per the manufacturer’s dilution recommendation, to one of the three-gallon aliquots as the treatment. I then divided the control and SUPERthrive treatment each into six individual, identical, two-quart containers. I thus had six independent replicates of a treatment and a control. (See Figure 1 below for a schematic of the experimental design.)

Figure 1. Outline of experimental design

To further avoid any experimenter bias, I had my wife assign numbers randomly to each container, record which were SUPERthrive treatment and which were untreated control, and then re-sort all the containers. I had no idea which containers contained which nutrient mix. I did not open the “secret decoder envelope” until after all measurements were complete!

Figure 2. Identical 2 quart containers randomized on day 1 in the hydroponics solutions. This kind of hydroponics is called “Kratky” or passive. Enough nutrient solution is supplied at the beginning to last the plant for its entire life-cycle.

Into each of the 12 containers I placed a 12-day-old lettuce seedling, taking care to select plants that were of equal size and leaf number. The containers were then placed under my lights (cool white T8 fluorescent) for the remainder of the experiment. I rotated the rows of plants several times to try to control for any edge effects in my grow area. After 30 days in the containers, I harvested and weighed each plant.

Figure 3. Plants after 30 days of growth.

What did my experiment show?

The graph below is a box and whisker plot that shows the spread of the data and the mean for each group in grams of harvested fresh weight of the plants (roots were removed). In my experiment, the SUPERthrive treatment showed a clear drop in harvested fresh weight! In fact, the heaviest SUPERthrive plant weighed less than the smallest control plant, and the SUPERthrive set was much more variable in harvested weight. These results surprised me a bit.

Figure 4. Box and whisker plot of lettuce plant fresh weight. Master Blend: Master Blend nutrients; Master Blend + ST: Master Blend nutrients plus SUPERthrive (0.9 ml/gal.)

A standard statistical test (Student’s T-test, unpaired, two-tailed) was performed to show that that there was in fact a statistically significant difference (p<<0.01) between the two groups. Thus, we can reject the H0 (remember our null hypothesis is that there will be no treatment effect) and conclude that there is a difference between treatment and control harvested weights, with the treatment mean plant weight being significantly smaller than the control mean plant weight.

What can we make of this experiment?

Well, we need to keep in mind a few things.

1) Six replicates is a very small sample size; this could be a spurious, unlucky result. There is always some distribution of growth rate, even in a uniform genotype. Did I get unlucky and happen to put six plants that would always be on the smaller end of that distribution into SUPERthrive?

2) After analyzing the data, I discovered that four of the SUPERthrive plants ended up in the same row and were the smallest heads in the experiment (sometimes you flip a coin and get four heads in a row!). Could this be the reason for the unexpected results? The other two treated plants were in the other two rows, but neither was as large as the smallest control plant.

3) I do not have a perfectly controlled environment like one would find in a lab or even in a larger growing facility. However, something marketed with such aggressive claims of amazing plant health benefits and vigor should give a noticeable effect under a variety of imperfect, real-world conditions, such as those one would find in a home garden situation, don’t you think?

4) Perhaps my plants were already growing at their maximum potential and there was nothing for SUPERthrive to “improve.” Afterall, hydroponics indoors is already a relatively stress-free environment, as the SUPERthrive manufacturer also points out. Then what do they think their product is improving in hydroponics? Would I have seen an effect under less-than-ideal or more stressful conditions then? This could certainly form the basis of other testable hypotheses.

Conclusions

What I think we can conclude is that in this experiment, with this genotype of lettuce, and under these hydroponics conditions and environment, SUPERthrive had no positive effect whatsoever and may have even had a negative effect. Under other conditions would one see a positive effect? Possibly. Would different plants or genotypes respond to the SUPERthrive differently? Possibly. We must always be careful of over-extrapolating both positive and negative results from a single experiment.

But, because the individual ingredients have not been shown to provide any beneficial effect, and no plausible mode of action is given by the manufacturer for their broad general claims, we should remain highly skeptical. As pointed out in the previous post, the SUPERthrive manufacturer has certainly had plenty of time to scientifically demonstrate efficacy of their product, since they proclaim to be “always ahead in science.”

Because the results showed a clear and unexpected negative effect, the experiment surely needs to be repeated. Repetition is a central tenet of science. I hope to share additional results with you in a post later this spring—after all, I have a whole bottle of SUPERthrive and we love salad!

References

  1. Banks, Jon & Percival, Glynn. (2012) Evaluation of Biostimulants to Control Guignardia Leaf Blotch (Guignardia aesculi) of Horsechestnut and Black Spot (Diplocarpon rosae) of Roses. Arboriculture & Urban Forestry. 38(6): 258–261
  2. Banks, Jon & Percival, Glynn. (2014) Failure of Foliar-Applied Biostimulants to Enhance Drought and Salt Tolerance in Urban Trees. Arboriculture & Urban Forestry 40(2): 78–83
  3. Chalker-Scott, Linda. (2019) The Efficacy and Environmental Consequences of Kelp-Based Garden Products.
  4. Yakhin Oleg I., Lubyanov Aleksandr A., Yakhin Ildus A., Brown Patrick H. (2017) Biostimulants in Plant Science: A Global Perspective. Front. Plant Sci., 7:249

Not all Extension publications are created equal

(A friendly caveat – this post does not lend itself well to images. So the pictures here are simply eye candy from my 2019 trip to London to reward you for considering this visually drab but important topic.)

The actual “whomping willow” in Kew Gardens

I’ve been involved in Extension education for 17 years and one of the most important things I’ve learned is that Extension audiences want information that’s easily understood and has obvious practical use. Most peer-reviewed research articles are written for academic audiences, so only the most persistent nonscientists will slog their way through pages of dense, technical writing.  It’s up to Extension educators to accurately translate and summarize technical scientific information for use by the public.

Epiphyte “tree” in Kew Gardens glasshouse

Extension is part of the American land-grant university system and extends traditional academic teaching to citizens statewide (hence the term “extension”). In addition to providing seminars and workshops to interest groups, Extension publishes educational materials in-house and provides them at low or no cost to their clientele.

The Bonsai Walk at RHS Wisley Gardens

But here’s the problem: the standards for Extension publications are set by each university. Unlike the peer-review system adopted by reputable journal publishers, Extension publications can vary widely in quality. Some universities have adopted a system that parallels that of scientific journals in that they require double-blind peer review. But many universities have not – and this means that looking for Extension publications on a particular topic results in a collection of materials with contradictory messages. This is incredibly frustrating to confused nonscientists and to Extension faculty who have to sift through the mess to find publications that are relevant and science-based. As a result, Extension publications are often regarded with suspicion by both nonscientists and academic faculty (who often do not have the disciplinary expertise to sort through the mess). Since I was a traditional academic before entering Extension, I have a foot in both camps.

Sunken gardens at Kensington

Nonscientists are probably not going to have the disciplinary expertise to tease out the good stuff from the dreck. But they can look for some indicators that will help them identify the most reliable publications. Here’s a checklist to start the process: the more “yes” answers you have, the better the chances are that the information is reliable.

  1. Is the author identified? Anonymous publications are not reliable.
  2. Is the author an expert? Expertise is determined by advanced degrees (at least a Master’s degree) in the subject matter.
  3. Is the publication peer reviewed? There should be a logo or a statement on the publication that says so.
  4. Is the publication relevant? High-quality Extension publications targeted towards commercial agricultural production are usually inappropriate for use in home gardens and landscapes.
  5. Is the publication current? Information relative to urban horticulture and arboriculture is rapidly changing. Publications over 10 years old likely do not contain the newest information.
  6. Are there scientific references included, either as citations or as additional readings?

As necessary as this process is for identifying reliable information, there can also be negative outcomes. Universities that do not have a rigorous process for publishing Extension materials put their Extension faculty into the uncomfortable position of having to defend their work when it’s questioned. It would benefit all parties for every land-grant university to institute a rigorous, peer-reviewed process for their Extension publications.

My favorite ad at the tube station

Hydroponics for the Holidays? Home Systems are a hot holiday gift list item

Systems to grow fresh produce in your home using hydroponics or other automatic processes have been popular for several years but seem to be even more popular this year with more folks home and looking for something to do and hoping to produce their own food.  As a result, these systems are popping up on holiday wish lists and gift buying guides all over the internet.  But are they worth it?  And if so, what should you look for in a system? 

First off, what are these systems? And what is hydroponics?  Hydroponics is the process of growing plants without soil in a aqueous nutrient solution.  Basically, you provide all the nutritional needs of the plants through nutrient fertilizers dissolved in water.  These systems can grow plants faster and in a smaller space than traditional soil-based production. It also allows you to grow plants indoors and in areas where you would not normally be able to grow.

This Aerogarden (which is the previous generation) has a digital brain that controls light and water schedules for the specific growth phase of the plant and yells at you when it thinks you need to add more fertilizer solution.

As for systems, you might have seen what is probably the “oldest” one on the market – the AeroGarden.  Since it is the oldest and most common, that’s the example we’ll be staying with.  It has been around a few decades and has evolved from a basic electronic system to fully automatic, “smart”Bluetooth connected systems that you can control with your phone.  In recent years there have been many new systems come onto the market at all different sizes and price points.  A quick search of online retailers will usually provide an array of options – from DIY kits to plug-and-play enclosed systems such as “Click & Grow” and “Gardyn”. My only experience is with the Aerogarden system, so I can’t speak to any of the others (though I’d love to try them out!).

The answer to “are they worth it” is up to you, really.  Most home based hydroponic or aeroponic systems offer convenience, but at a cost.  Most cost several hundred dollars and are small, so they produce a small amount of produce (or other plants) at any one time. So you have to determine what goals you, or your intended giftee, have with the system. 

“Baby” lettuce, 18 days after sowing. The current version of this 9-plant Aerogarden system, called the “Bounty”, retails for $300 but you can usually get it for under $200 on sale.

The benefit of the “plug-and-play” enclosed systems like the AeroGarden is that basically you can take it out of the box, set it up in less than 10 minutes, and have some fresh lettuce or herbs in a few weeks.  It controls the water cycles, lighting, and all other conditions for growth.  You just drop in pods that contain the seeds suspended in a spongy-material.  The smallest system, that holds 3 plants, retails for $100.  As an additional expense comes from buying refill kits to replant. The mid-size systems are the most common and range from $150-$300.  The largest system, the “XL Farm” retails for $600. But these systems are commonly on sale at pretty significant discounts. 

For many systems, you typically buy a new set of pods (there are different plant variety selections), but there are pods you can buy to assemble your own using your own seeds.  For the AeroGarden, the pod kits range from $15 up to $30 to grow up to 9 individual plants. There are other plug-and-play systems on the market, as well as some kits that are more build-your-own and less automated. 

No matter which systems you buy (or gift), keeping these costs in mind is important.  If you’re looking for a fun and easy activity with the benefit of a little fresh produce and aren’t as concerned with production costs these systems may be for you – and if you are giving or getting them as a gift that definitely makes it more economical. But given the cost of the plug-and-play systems and the refill pods, they will never be an “economical” option for producing your own food.  If you are wanting to produce food on a budget and you’re interested in home hydroponics, look for plans to build your own or buy a DIY kit. 

GPs at the Tradeshow: Looking for snake oil and finding…..the dirt on tillage

The Annual Meeting and Professional Improvement Conference of the National Association of County Extension Agents is that one time of year where extension agriculture professionals gather to share ideas, give talks, network, and let their hair down. The name of the organization is a bit outmoded: many states no longer call their extension personnel agents, but rather educators, experts, professionals, area specialists, and the like. Most aspects of agriculture are included: from the traditional cows and plows of animal science and agronomy to horticulture and sustainable agriculture (I’m the outgoing national chair of that committee). There’s also sharing on agriculture issues like seminars on engaging audiences about genetic engineering, teaching and technology like utilizing social media and interactive apps, and leadership skills.

It is the one time every year or so that Linda Chalker-Scott, grand founder of the Garden Professors, and I get to hang out. If we’re lucky we’ll meet up in some sessions, chat in the hallways, or grab a drink. But one of our favorite conference activities is taking a turn around the trade show floor. This is where companies and organizations are vying for the attention of extension educators to show them their newest equipment and products….we are, after all, the people that share growing and production information with a great number of potential clients across the country.

Since the organization runs on money, almost no company that comes calling with the money for a trade show spot is turned away. This means that the products may or may not stand up to the rigors of scientific accuracy. In years past we’ve found snake oil aplenty, like magical humic acid that is supposed to be this natural elixir of life for plant growth. The only problem is that humates don’t exist in nature and there’s little documentation of any effect on plant growth. The product that was supposed to be this magic potion was created from fossil fuels and no actual peer-reviewed research was offered by the company – hardly convincing. There were magic plastic rings that supposedly acted as protective mulch around mature trees and could slowly release water, except that mature trees don’t really need protective mulch and the amount of water would be negligible to a tree that size. So will we be smiling or scowling when we’ve made our way through the trade show.

Right off we set our sites on a company starting with “Bio”, which can be a good indicator of questionable rationale. That lit up the first indicator on our woo-ometer. Beneficial bacteria you apply to plants/soil: woo-ometer level two. So LCS and I engaged the representative. Asking about the product and what it does. We learned about their different products that could help increase the rate of decomposition of crop residues in farm fields, of turfgrass improvement, increased crop production, and treatment of manure pits on dairy and hog farms (which, if you’ve ever experienced one, you’d know would benefit from any help they can get in terms of smell).

Most of the products like this give vague descriptions of the beneficial bacteria it contains. They’re akin to compost teas that can have any number of good, bad, and downright ugly bacteria and fungi in them.  Since you don’t know what’s in these products, any claims on soils or plants are suspect at best. However…our rep went on to tell us that the company created blends of bacteria from specific strains that had been researched for their effects on decomposition, soil nutrient availability, and plant growth. There was a brochure with the specific bacteria listed, along with studies the company had conducted.

We asked about peer-reviewed research, which is our standard for evidence here at the GP, and while he had no results to share he assured us that university-led research is currently in the works. And as we’ve stated in regards to applying of beneficial bacteria to soil – while there’s little evidence showing the effectiveness of applying non-specific bacteria to plants, using directed applications of specific bacteria which have been tested for specific functions are supported by research. So our woo-meter didn’t fully light up. We reset it and continued the hunt.

We scoured the rest of the trade show and found one other soil additive that lit up the first lights of our woo-meter, but the rep must have been out for lunch so without anyone to talk to we couldn’t confirm woo or no-woo.

However…..we did find something spectacular! The local employees of the USDA NRCS (Natural Resources Conservation Service) had an interactive demonstration of soil, specifically showing the benefits of reducing or eliminating tillage. The NRCS works with many farmers to incorporate conservation practices on farms, including no-till production, by providing technical assistance, farm plans, and even grants, cost-share, and easement programs. Many farmers have benefitted from their grant for season extension high tunnels (which are seen as a soil conservation technique, since they shelter soil). We were so enamored with the demonstration, we asked them to do it again…so we could record it. So, for your viewing pleasure check out the video below where you can see how well no-till soil holds its structure while tilled soil falls apart. This effect is from the exudates from all the beneficial microbes in the soil that act like glue to promote good soil structure. We’ll let the video speak for itself……

So not only does the trade show get a smile instead of a scowl from us, but also two thumbs up! Either there has been some weeding out of the trade show sponsors, maybe the snake oil salesmen didn’t get the traction they were hoping for at the conference, or hopefully some of these companies have failed to reach an audience with their pseudoscience.

 

Is it good advice? Or is it CRAP?

In my educational seminars I’ve long shared a version of the CRAAP test (currency, relevance, authority, accuracy, and purpose) for analyzing information related to gardens and landscapes. My version is CRAP (credibility, relevance, accuracy, purpose), and we’ve published an Extension Manual that explains in detail how to apply it. This past week I was at the Philadelphia Flower Show participating in Bartlett’s Tree Care Update panel. Given that the theme of the show was “Flower Power,” I figured that a talk on Magical Mystery Cures was in order. And the 1960’s was the decade where the late Jerry Baker gained prominence as a garden authority – and whose presence is still widely felt nearly 60 years later.

And anthropomorphizing of plants begins….

 

 

 

 

 

 

 

 

 

Now, I could spend the rest of the year discussing all of Jerry’s advice, tips, and tonics for gardens – but it’s more useful to determine whether he is a credible source of reliable information. So let’s apply the CRAP test.

C = credibility. What are Jerry’s credentials as a garden expert? It’s easy to find this information from the internet, including the Jerry Baker website. He had no academic training in plant or soil sciences but started his career as an undercover cop who often posed as a landscaper. His books are all popular publications, meaning they have not gone through critical review by experts before publication.

R = relevance. For our purposes, his information is relevant to our focus of managing gardens and landscapes (as opposed to production agriculture, for instance).

A = accuracy. Jerry’s advice is not based on any scientific source. He relies on common-sense approaches, folklore, and his grandmother’s advice. In fact, many of his assertions are at odds with published scientific evidence. Now, science evolves, and older scientific publications are sometimes found to be inaccurate after new information comes to light. If Jerry’s books were meant to be accurate sources of information, they would be updated with new findings as subsequent editions were published. This is what happens with textbooks, for example.

P = purpose. What is Jerry’s ultimate purpose? It’s sales. There’s no way around this conclusion. Over twenty million copies of his books have been sold, and during his career he became the spokesperson for several gardening products. Probably the most well-known of these was the Garden Weasel (which parenthetically is a great way to destroy fine roots and soil structure). There’s no doubt he was a brilliant self-promoter and marketer. But he was not a reliable resource, and many of his “tips and tonics” are extraordinarily harmful to plants, pets, and the environment.

“Garden Weasel” courtesy of Wikipedia

While I was wrapping up my research on Jerry Baker I was particularly taken by a chapter in one of his books (one of his Back to Nature Almanacs) called “The Tree Quacks.” I thought some of these quotes were particularly ironic:

The source…

…and the quotes

 

 

 

 

 

 

 

Imagine my surprise when I discovered that these quotes were actually not his own. In fact, the entire chapter was plagiarized from a 1964 article by John Haller in Popular Science, which is online. This action is uncomfortably similar to his 1985 trademarking of the phrase “America’s Master Gardener,” 12 years after the Master Gardener program was formed (but not trademarked) at Washington State University.

Text from 1964 Popular Science article

I hope this post has helped you learn to analyze the credibility of information and information sources. If so, you can claim the of America’s Master CRAPper ™!

Native vs. nonnative – can’t we all just get along?

Probably the most contentious gardening topic I deal with online is the native vs. nonnative plant debate. This, unfortunately, is a debate that is more based in emotion than science, and I don’t intend to stir that pot again. We’ve discussed it on this blog before (you can find a list of them here), and I’ve published both a literature review and a fact sheet on the science relevant to tree and shrub selection. What I want to do in this post is compare two research papers, both in peer-reviewed journals, that come up with dramatically different conclusions.

The first has been getting a lot of publicity on the web and in social media. It was published just two days ago, but because of widespread PR prior to release it appears over 37,000 times in a Google search. The title “Nonnative plants reduce population growth of an insectivorous bird” – and much of the prerelease publicity about the article spells doom and gloom. It’s a message that gets traction.

The second was published a year earlier and is entitled “Native birds exploit leaf-mining moth larvae using a new North American host, non-native Lonicera maackii.” It appears 194 times in a Google search, even though it’s been available for over a year.

Amur honeysuckle (Lonicera maackii)

The reason I’m singling out these two articles is they have completely different messages – and one of them is not being heard as loudly as the other. The first focuses on a single bird species, the Carolina chickadee (Poecile carolinensis) and its diet in urban landscapes. Their conclusion: “…properties landscaped with nonnative plants function as populations sinks for insectivorous birds.” Thus, any gardener who happens to use introduced ornamental plants in their landscape is made to feel guilty for starving their insect-eating birds. (As an aside with my manuscript reviewer hat on – this statement has no business being in an abstract as it overextrapolates the research on one species to include ALL insectivorous birds.)

Carolina chickadee (Poecile carolinensis)

Black-capped chickadee (Poecile atricapillus)

 

 

 

 

 

The second article has a different focus. It reports the feeding of black-capped chickadees (Poecile atricapillus) on the larvae of a leaf-mining moth (Phyllonorycter emberizaepenella). While leaf miners are common food items for chickadees, the point of this article was to document the host of the leaf-miner – a nonnative and particularly invasive species of honeysuckle (Lonicera maackii).

Honeysuckle leaf miner (Phyllonorycter emberizaepenella)

 

Honeysuckle leaf miner damage

 

 

 

 

 

Chickadees as a group are particularly adept at finding and consuming leaf miners, whose tunnels normally protect them from insectivorous birds. Chickadees move along branches,“examining leaves both above and below them; the chickadees sometimes scanned by hanging upside-down.” This makes it easier to find and extract leaf-miners, as the underside of the leaf is easier to tear open than the surface. And in fact this behavior is reflected among other species of chickadee and leaf-miner: “Similarly, in 15 years of study, Connor et al. (1999) never observed species other than Carolina chickadees (Poecile carolinensis) feeding on the larvae of the gracillarid Cameraria hamadryadella [oak leaf miner].” While these are not the same species of leaf miner studied in this paper, the point is that chickadees eat leaf-mining insects. And leaf-miners can obviously adapt to new food sources, including introduced plants. This is basic ecological science.

Oak leaf miner damage

Oak leaf miner (Cameraria hamadryadella)

 

 

 

 

 

 

Neither Craves’s article (the second of these two articles) nor that by Connor et al. (cited within Craves’s article) are cited by Narango et al. (2018 – the first article), even though both are certainly pertinent to the topic. But they don’t fit the narrative – which is that introduced plants are not good food sources for the insects that chickadees eat. So they are left out of the discussion, which by default is now biased – not objective. Not science-based.

And I don’t have a good answer to the obvious question – which is why we continue to demonize noninvasive, introduced plants in the absence of a robust body of evidence supporting that view.

 

Hello Again, and a fun article that was called to my attention.

By Jeff Gillman (posted by Linda C-S, who has taken liberties with using photos from UNC Charlotte gardens that have nothing to do with Jeff’s post.)

Living arch at UNC Charlotte gardens

It has been almost two years since I have had the chance to post anything as a Garden Professor. Since then I’ve taken a job as the Director of UNC Charlotte Botanical Gardens and there are all kinds of things I’d like to share with you, and perhaps sometime over the next few weeks and months I will, but for now what is probably most pertinent is that I absolutely love my job. I am still doing some work on garden myths, but what I’m finding more entertaining is investigating the histories of different plants and their interactions with humans. In fact, in about a month or so, my friend Cindy Proctor and I will be releasing a podcast titled The Plants We Eat that investigates the interesting history, culture and biology of the various plants we use for food. We’ve already recorded shows on strawberries, grapes and mad honey, and we’ll be doing shows on apples, figs, and a few others before we release it – we want to have a decent backlog of shows so that we can maintain a pace of one podcast a week.

UNC Charlotte gardens

But enough about me! The current Gardens Professors called my attention to a recent article titled “The effect of ad hominem attacks on the evaluation of claims promoted by scientists”, and I found it informative to say the least. This article provides instructions on how to stop people from trusting a particular study.

No, seriously. If you wanted to you could actually rewrite this as a short manual on how to make people question the results of any scientific study.

And if you did I think it would look kind of like this:

(Short Disclaimer – I’m pretty sure that the authors of the above article never intended it to be taken in the way I’m presenting it. I’m posting this purely as satire.)

So, someone has published a scientific article that you disagree with. Hey, we’ve all been there. Scientific evidence that contradicts your beliefs/works/preconceived notions sucks, but it isn’t the end of the world. There are things you can do.

You might consider conducting your own well-designed experiments that would call into question some of the claims of the offending work. Once upon a time this was been the standard way to address this kind of problem, but this could take months or even years to accomplish. And the truth of the matter is that your experiment might not even say what you want it to and even if it does, with attention spans the way they are, nobody will even remember what you’re even talking about when your paper comes out.

Which is to say, there are better, faster ways to take care of inconvenient research, and that’s where this convenient manual comes into play.

Rain gardens at UNC Charlotte

First, realize that attacking the research itself isn’t a sure thing. Sure, it’s the right thing to do, but morals be damned, attacking the research itself can be waaaayyy too technical. People won’t understand what you’re talking about, so forget about it.

Attacking researchers personally by making nasty comments about where they graduated from college or that they do sloppy research would seem like winner, that kind of attack just doesn’t cut it today. Maybe it’s the political climate, but, to their credit, people just aren’t responding to non-specific personal attacks the way they once did.

So you’ve got to be smart and hit them where it hurts. You could say that data was fabricated in the paper that you want to discredit, but this could be problematic if it isn’t true. Not to worry. All you really need to do is find an instance where the researcher did do something wrong. In fact, it’s possible that some past misconduct could be even more effective at discrediting a paper than misconduct on the paper in question itself.

The gold standard, however, is conflict of interest. By establishing that the researcher who has caused you grief has some sort of conflict of interest you can cause people to question the results of research just about as effectively as if some sort of misconduct had taken place, and conflicts of interest are much easier to find! You could blame a company, a person, or even a University. Shoot, want to show that a study, which demonstrates that an herbicide is effective at controlling a weed, isn’t true? All you need to do is show that the company which makes the herbicide gave a few hundred dollars to an athletic program at the school, or show that one of the student workers in the lab has a second cousin employed by the company. It’s all good.

Water hyacinth

And so there you have it. The fast, easy way to discredit someone. And remember, just implying things can be as effective as having facts. No need to lie! Good Luck, and remember The Truth is What You Make It!

NON-GMO FERTILIZER?

http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1057077340&topicorder=3&maxto=14
Image courtesy of Plant & Soil Sciences eLibraryPRO at UNL

I was asked by Dr. Linda Chalker-Scott to look up some information in order to answer a recent comment and question on a previous post.

Paraphrased, the question is, “… are there any verifiable “organic” fertilizers that can be guaranteed to be made from 100 percent non-GMO sources.”

First off, let me state up front that the whole “Non-GMO” labeling effort is pure marketing. There is no evidence to suggest products that come from genetically engineered crops are any different than crops made from other plant breeding methods. The body of evidence in fact suggests they are as safe as their conventional counterparts, and have some excellent benefits to farmers and consumers from an economic and environmental standpoint.

Having gotten that disclosure out of the way, and assuming that price is not a factor, it turned out to be an interesting question to answer.

“USDA Certified Organic” fertilizers would be problematic, since there are exceptions to the organic standards, which allow manures fed GE crops to be used.

Similarly, oilseed meals like cottonseed, soybean meal, etc. also can be certified organic, even though they come from genetically engineered crops.

ALFALFA MEAL

https://commons.wikimedia.org/wiki/File:Lucerna_-_Budaörs.jpg
Alfalfa Field image courtesy of Wikimedia Commons

One possible alternative in that category is alfalfa meal, since genetically engineered alfalfa is currently grown on only 13.5% of alfalfa acreage, whereas in the case of cottonseed, soybean, sugar beet, and corn products, the rate of adoption of genetically engineered crops is well over 90% of U.S. acreage.

Only about 13.5 percent of harvested U.S. alfalfa acreage is genetically modified, compared to more than 90 percent of corn, soybeans, cotton, canola and sugar beets acres, according to a new USDA report that cites 2013 farmer surveys.

It appears likely the percentage of genetically engineered alfalfa will continue rising, though: Roughly one-third of newly seeded acreage planted that year was of a biotech variety resistant to glyphosate herbicides, USDA said.

Farmers have been slower to adopt genetically engineered alfalfa partly because it’s a perennial crop that stays in the ground for roughly five years, said Dan Putnam, an alfalfa extension specialist at the University of California-Davis.

It would be incumbent upon the buyer to ask, however, if the alfalfa meal came from a grower who does not use genetically engineered alfalfa, and whether or not the supplier of the alfalfa meal guarantees that.

MANURES FROM LIVESTOCK FED ONLY ORGANIC FORAGE

https://commons.wikimedia.org/wiki/File:Hestemøj.jpg
Manure, a field in Randers in Denmark. Image courtesy of Malene Thyssen at Wikimedia Commons

“Demeter USA” … the private certifying entity that guarantees “Biodyamic” preparations does require that any manures come from livestock fed only “USDA Certified Organic” feed. So manures that carry that seal should satisfy the question.

As an aside, here is Dr. Linda Chalker-Scott’s literature review of “Biodynamics” and why that certification has little science to recommend it.

Further, finding the product would be difficult, since it is primarily produced on-site at certified Biodyamic farms, and used there.

SEAWEED FERTILIZERS

https://commons.wikimedia.org/wiki/File:KelpforestI2500ppx.JPG
An underwater shot of a kelp forest. Image courtesy of Wikimedia Commons

Next products that might qualify are seaweed, or kelp products. There are no genetically engineered seaweed/kelp products I’m aware of. However, there are real concerns about the sustainability of harvesting seaweed and kelp from the wild.

Dr. Linda Chalker-Scott wrote about them here:

The ecological impacts of increased seaweed harvesting are currently under investigation and the possibility of significant ecosystem damage is real.

There is however, some interesting research and startup companies that are farming seaweed and kelp for a variety of potential uses.

I can’t however, find any products available for the home gardener that are sourced from this effort. Still early.

So, when it comes to seaweed/kelp products, you’ll have to (again) ask a reputable supplier to answer the “sustainable” question.

BAT GUANO

https://en.wikipedia.org/wiki/Bat_Cave_mine
Bat Cave Mine Image courtesy of Wikimedia Commons

In a similar vein, “Bat guano” products would also qualify as “non-genetically engineered”, but the sustainability question also comes into play. How is it harvested? 

I can’t deny that it’s a great fertilizer, but if you want to use an organic fertilizer why not at least consider one that is renewable instead of one that is from a limited resource and which may cause harm to a unique ecological system?

SEAFOOD BY-PRODUCTS

https://commons.wikimedia.org/wiki/File:PSM_V45_D079_Non_edible_fish_scrap_processing.jpg
Non edible fish scrap processing … Public Domain image from 1894

Fertilizers made from by-products of the seafood and fish industries, assuming they don’t come from aquaculture farms, since the livestock feed for those operations could be sourced from genetically engineered crops, do have a history.

Two links (there may be others, but these seem sufficient for now), a comprehensive review of products (including fertilizers) from the Alaska seafood industry, put together by Oregon State University

Fish Fertilizer Product Descriptions

Fertilizers are characterized by their Nitrogen-Phosphorous-Potassium content (N-P-K). Therefore all fish material will have some fertilizer value since fish contain protein which is Nitrogen,
the bone contains Phosphorous and the flesh and bone contain Potassium. Generally, fish products are re-allocated to fertilizer use for any number of reasons including quality too poor for feeding, volume too small to convert to fishmeal and oil, and an available agricultural market in the vicinity of the waste material.

And a similar document put together by Michigan State University about the use of fish by-products for other uses.

In an effort to help the Michigan fish processing industry find better solutions to handle fish processing waste materials, a project was initiated to determine the viability of composting fish waste.

CHILEAN NITRATE

https://commons.wikimedia.org/wiki/File:Dusičnan_sodný.JPG
Mined Sodium Nitrate (NaNO3) Image courtesy of Wikimedia commons

There is a mineral product called Chilean Nitrate or Nitrate of Soda that is mined from a desert in northern Chile that is allowable for use under the standards for organic production in the U.S. However, it is not allowed for use under Canadian, or international organic standards, and a change to prevent its use under U.S. standards is still pending. Up until 2012, this was the wording for its use.

Sodium nitrate, also known as chilean nitrate, cannot account for more than 20 percent of the N requirements of organic crops in the United States.

Its use is also prohibited by the International Federation of Organic Agriculture Movements (IFOAM) and most other standards for organic production outside the United States.

After 2012, the 20% restriction was dropped in the U.S.

The expiration of the current notation will effectively mean that sodium nitrate may be used in organic crop production without a specific restriction on the amount used: however, producers must continue to comply with all requirements of the soil fertility and crop nutrient management practice standard.

Although the National Organic Standards Board (NOSB) recommended that sodium nitrate become a completely prohibited nonsynthetic substance, the NOP has not issued rule-making to carry out this recommendation as of yet.

FEATHER MEAL

A by-product of the poultry industry.  Is it from poultry fed only non-GMO feed?

LOCALLY PRODUCED

The final piece of the puzzle can be found (only partly in jest) in Dr. Jeff Gillman’s post about a cheap, locally available source of Nitrogen.

You’d be saving yourself the cost of fertilizer, saving the environmental cost of shipping the fertilizer you might otherwise purchase, saving water, and you’d have something unique to tell your gardening friends about.  Win – win situation as far as I’m concerned.

In summary, I don’t buy into any of the fear-based marketing of products that come from genetic engineering. There may be (at this time) sources of alfalfa meal that do not come from genetically engineered sources.

Biodynamic manures certified by Demeter USA require that the animals be fed only “USDA Certified Organic” feed, but will be difficult to come by. Seaweed/Kelp and Bat guano products would qualify, but have major sustainability questions about them. Lots of potential with seafood/fish by products, and finally … a personal possible solution.

Many thanks to Emanuel Farrow, a consultant to both conventional and organic farmers, who helped point me in the right direction and provided important fact checking expertise for this post.