I made this little image to try and make a point, not about Bt or GMOs or organic agriculture (all important topics for another day), but about the use of buzz words. I’m tired of the way words like “chemical” and “natural” get thrown around to try and make things sound bad or good. Neither of them are particularly useful terms because the definition of chemical is so broad as to cover just about anything, and “Natural” is more-or-less meaningless and entirely subjective.
So, my simple plea is to not let emotionally loaded buzz words sway you, but dig into the actual research and evidence to make decisions about what you think is good or bad.
Rejoice, gardeners and homeowners, for your deliverance from the drudgery of raking leaves has arrived. Or so goes the proclamation from a viral article that popped up on social media this past fall.
The article in question was posted on the Woman’s Day magazine website based on information from the National Wildlife Federation As the article points out, leaving piles of leaves on the lawn are good “habitat” and homeowners should just let the leaves fall where they may for the sake of supporting critters in the lawn. Of course, you can always believe everything you see online, right? Let’s take a look at what research can tell us.
Not so fast. There are a few issues with this new proclamation. Not that I am a great fan of the rites of autumn that dictate that we remove leaves from the lawn. It is one of my least favorite garden tasks, as evidenced by the fact that I wait until every last leaf has fallen before I get the leaf blower out so I’m certain that I don’t have to do it more than once.
Many people rake up leaves in the lawn because of aesthetics — we don’t want our neighbors to see a messy lawn. But there are lots of other issues that leaving leaves on the lawn can cause. Let’s take a look at all the reasons why leaving a layer of leaves on the lawn may not be the best idea.
First, the claim that leaving leaves where the fall on the lawn provides “habitat” for wildlife. What wildlife? The original source suggests small mammals, butterflies, and moths — specifically providing a place for overwintering. While I’m sure that there are some perfectly nice little critters that will make their home in the leaf litter, I have a name for what a lot of those things that find their home in your new “habitat” may be— pests.
Plant debris provides excellent overwintering opportunities for many garden pests. I also suspect that some of the wildlife that would find a comfy abode in the leaf litter would be small rodents, like mice and voles, that would enjoy nothing more than to snack upon some of the woody plants in your landscape. I also found some research that says removing leaf litter from residential areas reduces populations of ticks (article). Definitely something I wouldn’t want to welcome with open arms to my lawn.
Now let’s think about how plants make their food — they use sunlight for the process of photosynthesis. The article in question advocates letting leaves pile up where they fall on the lawn. This means piling up on the grass (or in my case, whatever passes for green). A layer of leaves on top of the grass will inhibit the plants from making their own food. While grass may not be actively growing in the winter, as long as it is green, it can still perform photosynthesis and store the food for spring. Even if you have a species of grass that turns brown in the winter, a pile of leaves would become an issue when things warm up in the spring.
It also turns out that a thick layer of matted leaves on top of the soil can create a barrier that reduces oxygen in the soil — thus creating an anoxic condition that will reduce or damage roots. Not only do the leaves create a barrier, but research has shown that the rapid consumption of oxygen by leaf litter bacteria lead to anaerobic conditions in the leaf litter itself (article).
Give the reduction in sunlight and soil oxygen, grass can have a difficult time thriving in areas of heavy leaf litter. Some other research results I found indicate a layer of leaf litter reduces the amount of herbaceous plants (in woodland) (in a field study). If you think about it, you don’t see many small herbaceous understory plants in forests with lots of trees — it isn’t just the shade from the trees that causes a problem.
I’ll also point out that for dog owners, leaving a layer in the yard can make it much easier to fall prey to what we refer to as “yard bombs.” I’m sure other dog owners have felt this pain.
Now, I’ll be the first to tell you that leaves are a valuable resource for lawn and gardener, so don’t think that I’m anti-leaf. I put all of the leaves that fall in my yard to work for me. While leaving the leaves to pile up into layers on the lawn is not a good idea, using a mower to chip them up and leave them in place will provide valuable organic matter and nutrients for the soil. So if you don’t want to rake them up, run over them with the lawnmower so they will break down quickly into the soil (and don’t smother out the grass).
If you do rake up (or vacuum up) the leaves, there are a few things you can do with them. First, the shredded leaves make a good winter mulch for landscape beds (put the plant suppressing power to work controlling weeds). You can also bag them up and store them for use in composting next spring and summer when you have fresh green plants to add to them.
This article originally appeared in the Charleston Gazette-Mail on November 15 (sans citations).
You can find my other articles online at wvgardenguru.com
The seed catalogs have started showing up in the mail, and a great number of them include something like this on the first few pages:
Here’s the thing: NO ONE is selling genetically engineered seeds to home gardeners. There is one company, funded by kickstarter, that is trying to sell genetically engineered seeds of a glow-in-the-dark plant sometime in the future (though, like a lot of kickstarter project, the actual release date keeps getting delayed) but other than that, genetically engineered varieties are only being sold to commercial farmers, and only after the farmer has signed a pretty comprehensive licensing agreement.
You can go to the store and buy food made from genetically engineered varieties — essentially anything that contains corn and isn’t labeled as organic will be — and you can stop by the pet store and pick yourself up a fish with jellyfish genes, but no one is trying to sell you genetically engineered seeds.
So those pledges in seed catalogs promising they contain no GMO seeds are technically true, but also pretty meaningless. So if you are worried about accidentally getting a GMO variety, don’t be. And if you wish you COULD grow one, sorry, you are out of luck, unless that kickstarter project ever actually gets up and running.
A few years ago someone emailed me information on another garden miracle – this time a product called Mighty Wash. I found my notes on this product as I wondered what I should post about today. The sales information at the time advertised Mighty Wash as “frequency water” (which we’ll get to in a minute). Here’s part of the original advertisement:
“Mighty Wash is a new revolutionary way to solve your spider mite problem in all stages of development from eggs to adults…Mighty Wash is a ready to use “Frequency Imprinted” foliar spray. It is imprinted with special frequencies which target fleshy bodied insects. The use of frequency is nothing new to our world, and as you probably know all things have a frequency. What makes our products special is the fact that our proprietary frequencies are holding and stable for at least 2 years and running.
“One attribute of our Mighty wash is that it paralyzes the insect on contact not allowing it to flood out eggs and begin the resistance process! Essentially there is no resilience that can be gained from or product unlike so many others, and without the use of any chemicals. Mighty Wash does have very low levels of our naturally derived botanical oils, along with frequency make it the cleanest solution to your spider mite problem.”
When I looked for the manufacturer’s current information (an LLC called NPK), I couldn’t find reference to “frequency water” and its miraculous properties. After a bit of internet digging, I discovered that Mighty Wash was the subject of a bitter trademark dispute. For me, the best thing about this dispute is the deposition, which states exactly what the original makers of Mighty Wash claim their products do:
“Yeti invented and manufactures three plant washes using a confidential and proprietary formula and process that includes electronic frequency imprinting.”
They accused the defendant of making knock off products “not manufactured using Yeti’s proprietary formula and process” resulting in products “substantially less effective than Yeti’s Products.”
Leaving the legal battle for a minute, let’s see try to figure out how this product is manufactured. “Frequency Water” is water that’s been exposed to vibrational energy or to minute quantities of dissolved substances. That’s the “electronic frequency imprinting” which is referred to in the legal complaint; it’s also called “water memory” and is the foundation for explaining how homeopathic dilutions work.
It will come as no surprise to readers of this blog that there’s no reliable, published science behind any of this. What is surprising is the amount of money these companies make on selling water in a spray bottle. Mighty Wash and related washes (PM Wash, Power Wash, and Ultimate Wash [which is “Mighty Wash without food coloring”]) must generate healthy sales for two companies to squabble over the trademark of a product that is basically…water.
And the Irony Prize goes to the charges of fraud and false advertising leveled at NPK by Yeti Enterprises.
Those of you that have followed The Garden Professors for some time know that Jeff Gillman and I are relentless in our pursuit of gardening myths to explode. Social media – Facebook in particular – seems to be a natural breeding ground for dumb and/or dangerous home remedies that go viral. Most of these have no basis in actual science and are easy to dismiss. Other recommendations may have some science behind them, but a careful review of the literature often shows that the bulk of research does not support that particular practice or product. These ones are trickier to deal with, and nothing has been trickier for either me or Jeff than compost tea.
The two of us have posted extensively on this topic in the last six years: just use the search function over in the left hand column of this blog and type in “compost tea”. You’ll find enough reading to keep you busy for a while. I summarized the state of the literature a few years ago in the now-defunct MasterGardener Magazine and to be honest the accumulated literature hasn’t changed much in terms of generating solid science supporting compost tea use. But its popularity seems to be increasing among landscape professionals and gardeners alike.
I get a lot of questions on compost tea from Master Gardeners in particular, who are bound by their positions as university volunteers to use science-based information. One of their major resources is the state university associated with their program – and recently this has become a problem for WSU Master Gardeners. Because on the Washington State University website you can find one professor who cites the lack of credible, consistent science on compost tea usage and another professor who provides workshops and webinars on making and using compost tea. Master Gardeners are understandably confused about what they can recommend and irritated that their university provides conflicting information. Why, they ask, does the university allow this to happen?
The answer is found in one of the most important values that universities protect: the academic freedom for faculty to speak their minds. Ideally this means that faculty can speak up about topics that are unpopular with university administrators without fear of reprisal, but it also means faculty have a soapbox on pretty much any topic they wish. And that’s whether or not they have any expertise or credibility on that topic. (For a particularly egregious example, one needs look no farther than prestigious MIT who has a research scientist with no expertise in biology or chemistry but who publishes articles in marginal journals linking glyphosate – the active ingredient in Roundup – to just about every known human malady.) Universities tend not step into this fray as it is a slippery slope – who decides what faculty speech should be censured and which should not?
How can Master Gardeners and others decide what information to believe? Well, that’s actually the mission of this blog and our Facebook page and group – to provide the best current gardening science and to help the public increase their scientific literacy skills. Science is not immutable – it advances as credible, published evidence accumulates. When and if compost tea ever becomes a consistent, effective product, we will be the first ones to share that information.
Though psychology was the subject of this study, you shouldn’t assume the results were unique to that particular field. The are plenty of reports of similar failings and the so-called ‘Decline effect’ in other scientific disciplines.
So why is that? There are a lot of reasons. Research can be poorly designed, based on flawed assumptions, and sometimes an unlucky flukes can create false positives. It is also the sad fact that science is done by humans, and humans are complex things with a lot of motives besides the pure quest of knowledge.
I think the general public often fears that scientists are swayed by money from corporations and/or special interest groups, but my experience in academia is quite different. I’ve never heard anyone concerned they might loose a corporate grant. I have heard lots of people, more-or-less continuously, worrying that if their experiment doesn’t work out they won’t be able to get their PhD, land a job, or get tenure. There is enormous pressure to find something significant, to find an effect, and it matters not at all the political ramifications of that effect. So if you are worried about Monsanto buying off scientists to say GMO are safe to eat, don’t be. Convincing data that GMOs are somehow unsafe to eat would be of enormous significance, completely rewriting what we know about genetics, and would come with huge professional rewards. In my opinion, you should be more concerned that some new study showing that X, Y or Z makes plants grow bigger or yield more is actually the result of fervent, wishful thinking on the part of a grad student desperate for publishable data.
So what’s the solution? There has been a lot of talk in the academic community about making it possible to publish negative results and provide funding to regularly attempt to replicate previous studies. I hope these changes go into effect, as they could make an enormous improvement in the reliability of new findings.
In the mean time, you, as a concerned gardener, should take information supported by only a single, isolated study with a big grain of salt, particularly if it seems to contradict findings from other research. If you go to scholar.google.com and start searching around, make sure you read as much of the research on the topic as you can, so you can differentiate between the intriguing new research that may well be proved wrong and reliable findings that have been sustained by several independent researchers. And always remember that while the scientific process is far from perfect, it is still the best we’ve got.
With many new nursery catalogs arriving in my mailbox at work for 2016 introductions, I thought I would focus this blog on “new” plants. With all the publicity and marketing that goes on for new plant introductions, you would think that they are the next best thing since draft beer or even bread! I am a bit cynical and question whether these new plants really live up to their performance expectations and ornamental attributes. With so many new hydrangeas, coneflowers, coralbells, spireas, etc. released each year, you may ask why am I so cynical? Why would I not jump on the bandwagon and promote all of these new plants like so many garden centers are doing across America? Let me explain.
A decade ago, I conducted research trials evaluating 20 new or recently introduced cultivars of “hardy” shrub roses, many of which are not even on the market anymore. I chose three locations in the state of Wisconsin, each having their own unique soil types, pH, soil drainage and fertility, rain/snowfall and cold hardiness zones. I replicated each of the 20 cultivars ten times at each location and arranged them into blocks with each cultivar represented in each of the ten blocks. The roses were randomly selected for each block and planted, mulched, watered with an application of a slow-release fertilizer. Plants were watered for the first year only as needed. To properly analyze plants for various traits, I allowed the roses to establish for a year with evaluation initiated the following spring. The only care the roses received the remaining years were application of a slow-release fertilizer, weeding and pruning of dead wood following winter. I was trying to replicate conditions that are common in most landscape settings. I did not spray any insecticides or fungicides to any of the roses, regardless of how bad they may have looked due to pests.
After the first winter, I evaluated the roses for winter injury, which they all experienced. The roses were all on their own root systems so if they died back significantly, the new growth would come from the same root system and produce flowers that spring. To some extent, they all grew, though voles killed some of the roses. After the roses starting growing, I evaluated them monthly at all three locations for insects and diseases as well as flowering (amount, size, duration of bloom, etc.). I also measured the plant’s height and spread. A few roses had good fall color. The first year of the trial, the roses all bloomed prolifically. So, one would think that all 20 cultivars are ideal. Not so fast, or “but wait, there’s more” as the television salesman would say to viewers in TV land about a new product. The “real” evaluation started in year two.
In year two, amount of dieback and winter survivability was recorded. To my surprise, the roses in the zone 3 location (boy, that’s cold) had better winter survival than the roses in my zone 4 and 5 location! This is due to consistent and significant snowfall in the most northern location compared to sporadic snowfall and lower amounts in the other two locations. I also evaluated the roses during the summer and fall for flowering, pests, and hip production. Contrary to the catalogs, many of the roses had hips, but some of them never colored up before the cold temperatures arrived at the three locations. Flower production was cited as being continuous all summer by their introducers, however, this was not true for some of the cultivars evaluated. Disease resistance was the most alarming quality I evaluated with many of the so-called “disease resistant” roses being the exact opposite. I explain all these variables to demonstrate what is involved in proper plant evaluation. For a complete report of my rose research trial, see: Jull, L.G. 2004. Hardy Shrub Rose Research Trials. Combined Proceedings of the International Plant Propagators Society vol. 54:429-434.
Now, you may ask, “Why are these new plants, including roses, promoted by these large nurseries as being the best plant around when in effect, they are not?” Many new introductions are from nurseries that trial their plants in their location only. So a plant that performs well in the state of California might not perform the same in Michigan and vice versa. There isn’t the scientific rigor applied to these new plant evaluations that would occur by non-biased, university researchers who have no stake in selling or promoting plants to the public. This is where the beauty of applied, scientific, university-based studies can play a huge role.
Also, these new plants should be evaluated over numerous years, at various locations/soil types, climates, with appropriate replications of each new plant in a random arrangement (not all planted together). This type of quality research is done by a few large nurseries but it is seldom done this extensively by others anymore as demand for new plants is never satisfied and the cost of trialing over several years and locations is too costly.
Unfortunately with increased costs and significant budget/program cuts, most university research is now geared toward larger, basic science studies that have high indirect costs built into the grants. These funds, usually 50% or more of the grant total, go directly to the university to cover overhead. The researchers do not see or can use overhead funds. Ornamental plant evaluation research is now considered either non-fundable by granting agencies, not “scientific or scholarly” enough by their own departmental colleagues or provide significant overhead funds back to the university.
Some researchers rely on their various nursery and landscape associations for small amounts of research support, while others try to piece meal together small amounts of research funds. With the increasing costs of land (yes, we do have to pay for research space at university research stations), plants (not all are freely given to the researchers), labor, supplies, etc., it is becoming critically important to seek alternative funding sources as most federal and state granting agencies do not fund ornamental plant evaluation research. Many of the new initiatives for federal grants seek to fund food crop based research, especially in organic and sustainable food production. Applied ornamental horticulture plant evaluation research at universities has plummeted with most new plant evaluations conducted by the large nurseries that introduce these plants.
There is another source for evaluation of these new plants. Various arboreta and botanical gardens around the U.S. are conducting evaluation trials. I am a fan of these studies as these gardens and evaluators are also not in the business of selling plants and can provide some analysis, though it is usually only at one location. Richard Hawke, Chicago Botanic Gardens Plant Evaluator and Horticulturist, has done an excellent job of evaluating many species of herbaceous perennials and a few woody plants. He publishes Plant Evaluation Notes: (http://www.chicagobotanic.org/research/ornamental_plant_research/plant_evaluation), a series of wonderful publications that help both the amateur and professional gardener to choose appropriate plants for the Upper Midwest. There are other botanical gardens and arboreta that do the same, with evaluations based on their local climatic conditions. I often rely on Mr. Hawke’s recommendations when choosing herbaceous perennials in my Wisconsin garden and have yet to be disappointed.
So the next time a new plant comes across your way, think twice before buying it. There is the philosophy “Buyer Beware”, and I do recommend people to buy plants, but instead of buying 10 of one cultivar, try one or two of the new plant and make a judgment call the following year or two after you planted it. This is especially important for landscapers who design and plant large amounts of plants. You might be surprised to see the “best thing since draft beer” plant being anything but that. As some of us know, there is nothing better than draft beer (or whatever beverage you really like).