And here's Jeff!

As promised, here's a follow-up interview with Jeff Gillman, author of The Truth About Organic Gardening. He's responding to my questions, Susan's post, and your comments. First a brief word from Jeff, and then the questions (in ital) and his answers.

Thanks for having me back! And all of those points that you disagree with me on? I'm right and you're wrong. OK? No? Nuts, I should have known you people would be more demanding than that.

I'm happy to see there's disagreement with some of the things I've written. One of the reasons I love this blog is that there are so many well-educated opinions represented here. It shows that people are thinking about what they're doing and that's the real goal of my books—to inspire people to think and not just accept the advice given them, regardless of who it comes from. All we can do is gather evidence (and I hope that my books provide a starting point for evidence seekers), make informed decisions, and hope for the best.

What about the regular use of ordinary compost? As you can see, both Susan and Terry (one of our commenters), question using it yearly, as you recommend.

Compost adds organic material to the soil along with micronutrients and macronutrients. Though it may seem excessive, the amount of compost that I recommended really isn't that extreme at all and often experts will recommend adding more, especially in poor, sandy soils. Are yearly additions too frequent? Not in most cases. You would be amazed at how much of this material can be lost through erosion, and even leaching in sandy soils. In a garden where food plants are grown and harvested, little organic material is returned to the soil because weeds aren't allowed to grow and die, and because the plants that are harvested are, obviously, prevented from adding much organic material to the garden. In these cases additions of compost are about the best thing that you can do to renew nutrients and organic material.

Having said that, I am a big fan of no-till gardening (though I understand why people till and don't think that it's appropriate to discard this management option out of hand) and I particularly like Lee Reich's book Weedless Gardening. In this situation mulch is used (usually added yearly) which slowly composts and becomes incorporated into the soil. Now certainly some people live on land that naturally contains high levels of organic matter and nutrients. These people are very lucky and it is likely that they will not need lots of compost to maintain organic matter or fertility—at least at first—until the ground has been used carelessly for many years. But I still contend that most of us are better off adding some form of organic matter yearly. If the amount that I recommend seems excessive to you, then you should add less, or, better yet, run an experiment on your garden where a portion receives yearly compost additions and a portion doesn't. Let the experiment run for five years and see which portion does best!

I mentioned using quick-acting synthetic fertilizers for my containers, where I need fast and continuous performance. You seemed to agree, I thought. Do you?

I think that quick acting synthetic fertilizers for containers are fine. In my experience they do work better for plants in containers than organic fertilizers—it's tough to beat the quick growth response you can get from something like Miracle Gro. I certainly use them in my research plots. However, as a rule, I tend to prefer renewable organic fertilizers simply because of the sustainability issue. To make a poor analogy, I also prefer bicycling because it doesn't use our quickly diminishing supply of oil—but I still drive a car because it's a lot faster. My conscience is comfortable with this, but the consciences of others might not be. It's up to each of us to decide whether our choices make us bad people.

While we're on the topic of fertilizer, Susan asks about Dynamite Plant Food, which is a synthetic, slow release she's heard good things about. Are you familiar?

I'm not familiar with this product in particular; however, I am familiar with similar products and, in general, they work extremely well. I would certainly expect this to be very effective —it seems very similar to a now extinct product called Nutricote (which was the best slow release fertilizer I ever used). I would like to comment that when I looked this fertilizer up I found they were offering a flower and vegetable formulation loaded with phosphorus (it's a 13-13-13). This is more phosphorus than plants really need. Their general purpose fertilizer seems much more in line with what plants actually require regardless of whether there's a flower or vegetable involved (it's an 18-6-8).

I am sure you've heard that everyone's Japanese beetle problems seem to be increasing. Thoughts?

Inundating the landscape with pesticides is a bad idea, period. Japanese beetles suck, period. Rock and a hard place ... There are few effective non-chemical ways to control the Japanese beetle. People talk about milky spore disease, but over time it has produced unimpressive results. Likewise, nematodes can provide a little bit of control, but not enough to make most gardeners/foresters/landscapers/etc. happy. Japanese beetle traps are best used as a joke present for a despised neighbor (they attract more beetles than they catch). Personally, I was born in PA and saw some pretty bad infestations growing up. Mostly we ignored them and eventually the environment limited their populations all by itself without our help. Unless the beetles are destroying your garden, I'd let them be. If they are destroying the garden—well, unfortunately that means that a pesticide will probably need to be used. In terms of the government—be it local, state or federal—trying to control this pest [as it is in Orem, Utah, where residents are being asked to stop gardening for 3 years], I know they're doing the best they can to control a noxious insect, but I tend to err on the side of allowing the insect to spread rather than apply pesticides (lots of my colleagues disagree with me). It’s a terrible damned if you do damned if you don't situation, and, while I'm happy to offer my opinion, I'm not going to claim that I have any amazing insights.

What about this comment: "the companies themselves are fundamentally not even curious about possible long-term ecosystem or health effects."

Wow! who made that comment? I work on a semi-regular basis with people who research and sell pesticides. I can tell you that individuals within the companies are concerned. However, I will be the first to admit that as a whole these companies seem to value the dollar above a healthy environment. Since I don't actually work for a pesticide company I can't tell you much about the inner workings of one, but I do periodically test pesticides and talk with their representatives and I work with many researchers who communicate regularly with these companies so my perspective might be a little different than that of many of the ranters. To let you know how I feel about these companies it's probably best to draw a comparison to the most evil companies ever: tobacco companies. Tobacco companies actively lied about their research to promote the use of their product. I think that pesticide companies are a touch better. In my experience they don't cover up an experiment that points out problems with their products (and I do personally know a few researchers who have done work on problem pesticides and published without any repercussions or censorship). … Chemical companies are out to make a buck, and they're not looking as closely as they should for potential problems, but if they do happen to find one, or if one is called to their attention, they do tend to respond (though their responses are often too little too late—as with Atrazine or Round-up ready GMOs). Are their responses designed more to placate than because these companies care about the environment? That's for you to discuss.

Are there there new areas of research you're working on that would be of interest to our readers?

I do have a couple of interesting projects that I am working on, two of which I'll share here. One is a home remedy for disease and one concerns a common recommendation coming from the extension service. First the disease control. Every year since The Truth About Garden Remedies came out I have conducted some sort of field trial where I look at different sprays for powdery mildew and black spot on roses. I've had lots of failures including Cornell mix (baking soda, oil, and soap), aspirin (which I've got to try again based on an e-mail from a group in NH) and others, but only one true success. But what a success it was! By spraying a mix of milk and water on the roses weekly we got control of black spot that rivaled any synthetic or organic fungicide. And we're not the only ones to have found that milk helps to control plant disease; many other researchers have found exactly the same thing. It doesn't seem to matter what type of milk: whole, 1%, 2%, skim, even powdered seem to work. Also, the concentration of the milk in the water seems to be able to be varied: one part milk to two parts water seems a good place to start if you want to try this remedy, and it'll provide some fertility to your soil or media too! Though we did notice a mildly unpleasant odor now and again...

Our other research is more controversial because it's contrary to what everybody "knows" about transplanting trees and shrubs Everyone knows that when a tree or shrub is in a container for too long the roots will start to circle around the container and create a pot-bound condition. But when we tried planting pot-bound shrubs that were butterflied (the soil ball divided into two sections), scored (this is basically the recommendation that you'll receive from your extension service where the sides of the root ball are sliced at four evenly spaced locations around its circumference and across the bottom in a big X) or where the roots were teased out, we found that none of these techniques had any effect on the number and size of roots emanating from the original root mass. And other researchers have found exactly the same thing! What does it mean to you? Nothing yet. This is so contrary to what we expected, we're doing another, long-term experiment with many more species. For right now continue to cut those root balls—but don't be surprised if recommendations change in a couple of years or so ...

How about this comment: "The one thing that has been ignored in the discussion of whether Roundup is harmful is this: the more people who consider it relatively safe and use it, the bigger evolutionary pressure it becomes, and the sooner plants (which are chemical factories in their own right) will evolve around it. IIRC, Scott's just got whacked with a major fine for mismanaging field trials for Roundup-ready creeping bentgrass, to wit the 'resistant' plant escaped and is considered invasive and has to be eradicated (with what, I wonder?)".

It is true that the more Round-up is used the more likely we are to select for plants that are resistant to Round-up, and indeed there are a few cases where plants have developed some level of resistance, but these are pretty rare (which is surprising considering that Round-up has been used for over thirty years). It's a good argument for using less Round-up and I certainly think that, if you can avoid any herbicide, that's a good thing. But if I had a big patch of ground to clear I'd still use it. Resistance is driven by repeated use of a chemical on the same population. If a compound is only used once in a while then you're not going to force plants to develop resistance, and, even if resistance is seen, it would be quickly lost because it would only be beneficial to the plant for a brief time (typically resistance to a chemical costs an organism strength. Hence, a resistance gene or genes are a liability unless the chemical is actually present). Regarding the genetically modified grasses that can't be killed with Round-up: honestly I do worry about those Round-up ready GMOs escaping and becoming terrible weeds. I don't think it's likely, but it's a possibility that we need to take very, very seriously.

Comments

[Terry]

Thanks for interviewing Jeff, Elizabeth! I agree that he's really onto an excellent method of viewing the horticultural world!

However, I'm still not convinced of the universal benefit of using compost? The point in my previous post was that people from around the world read this blog - and some (many) live in places and grow plants that may not appreciate the addition of organic matter. In other words, it's critical to understand the site and plant - and act accordingly.

Meanwhile, maybe in a future interview you can find someone clever to explain (much better than I can) that individual plants exposed to Roundup (or other selective pressures) do not "mutate" and develop resistance. Rather, genes that confer resistance have existed within a given population of plants for thousands to millions of years.

Obviously, those genes became part of the makeup of that population of plants as a result of some other selective pressure many, many, many years years ago and just happen to provide resistance to Roundup, or other pressures in the modern world.

The only way that the Roundup resistance is expressed is that most of the plants that don't contain genetic resistance are killed, leaving a greater percentage of plants with natural resistance to pass along their genetic (resistance) information to the next generation.

Anyway, my point is that the genetic ability to resist the effects of Roundup (and/or other selective pressures) have existed on the face of the plant for thousands to millions of years. It's not some sort of "mad scientist mutation" within a given plant that was caused by direct exposure to Roundup (or, again, any other selective pressure)

(See, I told you that I'm not the one to clearly explain how this process works in nature;-)

[eliz]

Terry, the thing I've been wanting to point out for some time is that I feel absolutely no responsibility to whomever these "people around the world" are who may be (horrible thought) hanging on my every word and taking it as gospel. This is a blog, which by its very nature is subjective, opinionated. I say what I think here and I love it that people disagree. That's great.

This is a gardening discussion--by gardeners. None of us ranters pretend to be horticultural experts. I am glad that people have your dissenting view to read, especially if I'm as off base on compost as you say! As for Round-up, you bring up great points. (Thank goodness I never need to use it.)

[MaryContrary]

Actually, my Japanese beetle problems seems to be ... decreasing.

I have used neither milky spore nor nematodes, but I never use broad spectrum pesticides indiscriminately(my worst offenses are neem on the harlequin beetles in the horseradish and dilute daconil for some tomato fungal problems) and really have learned that most things balance themselves out if you quit killing everything off and don't sweat a little gnawing here and there. I'm headed into year 10 of organic (well, mostly) gardening in my yard, where, in terms of plants, I've gone from weedy lawn and precisely 1 mature ilex opaca to very little lawn and a diverse range of plants with good wildlife value. I've also gotten most of my near neighbors off of the toxic sprayer. I don't know if it's the birds or the predatory insects, or what, but the JB population has gone done and the damage is more than tolerable and controllable with some hand-squishing (very satisfactory) and a occasionally a little early morning tour with the beer cup of soapy water. Yeah, there are always a few on the rugosas, the soybeans, the borage, but, eh.

[Michele Owens]

Fascinating conversation! Thank you, Elizabeth and Jeff. I have to say, though, that at age 47, I am now firmly placed in the MaryContrary camp. I take a completely fatalistic approach to all gardening challenges. I'm firmly convinced that no problem is ever solved--only the gardener changes. So if Japanese beetles were destroying my garden, I wouldn't bring out what Jeff suggests are the inevitable pesticides. I'd call a realtor and move. Really, it would be easier.

[susan harris]

To clarify, I questioned the TILLING of compost into our gardens yearly. Unlike Terry, I see nothing wrong with the application of compost - as long as it's ON TOP OF the soil, not tilled into it. My own practice is to apply leafmold mulch every spring to my whole garden, though this year I'll be spraying compost tea, too, just to see if it makes a difference.

[Jeff Gillman]

Susan,

When you add the compost tea could you add it to one section of the garden and not another? I'd love to hear from someone who's run a little experiment on these things. I often ask audiences their experiences with compost teas. I usually get about a 50-50 split of people who say "yes it worked" or "no it didn't" (I recently had someone come up to me after a talk and say that it worked but that they had recurring stomach flu until they stopped using it -- but I don't read too much into that -- yet). The problem is that no-one runs a real experiment where they test some plants with and some plants without.

[firefly]

Round-up resistant grass was engineered in a laboratory specifically for use on golf courses and athletic fields. It is meant to hold up under repeated applications of Round-up while all the 'nonresistant' weeds are killed so that the golf courses and playing fields can look like green carpeting. Roundup resistant soybeans are also commercially cultivated.

It is not a natural resistance to Roundup that is the problem (in fact, the people behind creeping bentgrass are counting on the lack of resistance in natural populations). The weeds are just supposed to die season after season. Like insects, though, they are also capable of developing a (parallel) resistance to chemicals.

What they also don't count on, and what is typically utterly mismanaged, is the way plants can interbreed (hybrids backcrossing with native relatives) and redevelop the ability to reproduce even if they've formerly been 'sterile.'

I don't claim to have first-hand knowledge of this research, but the book I'm reading now is a compendium of scientific studies on alien and invasive species' interactions with each other and native environments, and it is sobering stuff.

The point I think should be addressed is this knowledge is out there and yet things like GMO grass are not tested for all likely possible interactions before they are loosed on the world. As the Scott's case shows, even the tests can be bungled.

A gardener using Roundup as a one-time thing may not cause much of a problem in local terms, but when it's added together with all the putting greens and playing fields (and potential industrial agricultural applications), what's the cumulative effect?

[susan harris]

I can't stay away from this discussion. Thanks to Jeff and Eliz!
To Terry: What Eliz said. I'm pretty sure (actually very sure) our readers don't regard the GardenRant writers as authorities, and we don't pretend to be. This is a community of *gardeners*.
And about seeing the use of insecticides as inevitable if nothing else works, I'm with Michele. Replace the frigging plant! It's clearly not the right one to grow there.

[susan harris]

Oh, and there's this. Jeff said: "I often ask audiences their experiences with compost teas. I usually get about a 50-50 split of people who say "yes it worked" or "no it didn't". Not exactly scientific, and shouldn't data only be gathered from people who used the right KIND of compost tea, aerated stuff?
And "The problem is that no-one runs a real experiment where they test some plants with and some plants without." Well, Jeff Lowenfels' slide show includes several examples of fields that are half compost tea-treated and half not with clearly better results on the tea side. Why don't those experiments count?

[Commonweeder]

I've bought Round Up, the only herbicide ( or pesticide) I've even contemplated using, but then was afraid to use it. I have to say Jeff has emboldened me, and I may get rid of an invasive clematis. I plan to buy both his books. Also, when we moved to our 'farm' 27 years ago, I had trouble with Japanese beetles and used milky spore - and now I don't have beetles. This is only anecdotal, but I'm glad I made the investment. I'm also happy to learn about milk as black spot cure. My hardy roses aren't much affected, but its good to know about.

[Jeff Gillman]

Hi Susan,

They don't count because I haven't seen them and had the chance to critically analyze them. Boy that seems kind of flippant, but it's true. If I don't see the results and hear about how they were gathered then I have to discard the research as interesting but unconvincing. I encourage(d) you to do the experiments to convince yourself one way or the other -- because that's what I believe gardeners should do with new techniques that they want to try. I have my opinions (obviously) and I hope you take my thoughts and research into account, but hey, I appreciate the fact that it's your garden and it's not my job to tell you what or what not to do. I do love to hear from people who run experiments and these can certainly affect my thinking (which is why I'd love to hear about your experiences), but unless a study is laid out in such a way that I can really go over the materials, methods and results it won't change my mind.

And, OK, I agree that the 50-50 split is pretty unscientific.

Yes, if I were to do a real survey I would need to distinguish exactly what kind of compost tea I were testing (I would choose not to say "right kind of compost tea", because different people have very different ideas about what the right type of compost tea is. In fact, if you look at the scientific literature, non-aerated compost tea is the best stuff for helping to control plant disease).

Finally, we've done the compost tea thing to death, but I'll add a point just because I can't stop myself. I would expect plots which show the side treated with compost tea to look better than the other for the simple reason that the side treated with compost tea had additional nutrients added to it through the compost. If we are to believe that the benefit to the crops came from microbes rather than from nutrients in the compost you need to treat the non-compost tea treated side with sterilized compost tea containing exactly the same nutrients (and in exactly the same way).

Additionally, were the plots that were shown farm land? If so there are significant differences between disturbed farm land and your garden which could make the comparison mute.

All that said -- compost tea may very well work but I still worry about its safety.

[Lisa Albert]

Great interview, fascinating stuff, thank you, everyone.

Michelle, too funny that you'd move instead of battle. Does that qualify as run away and live to fight another day? I haven't yet resorted to moving but I have removed plants that refused to grow without artificial means of support.

(Conveniently ignoring Jeff's comment that we've done compost tea to death) When compost tea started making news, I asked Glen Andreson, Metro's natural gardening educator, for more information (he's a fabulous source for us Portlanders). He told me that since making compost isn't an exact science, the end result can vary, which can affect compost tea results. And it's not just the quality of compost that makes a difference. The kind of compost - fungal-based or bacterial-based - will also affect the end result. There are quite a few variables that can make anecdotal testing hit and miss for us gardeners.

I have more to say but the words aren't flowing. I'm trying new progressive lens glasses today and it seems that my swimming vision is affecting my brain's processes (hey, that's my story and I'm sticking with it!).

[sarahliz]

I have to say I'm a fairly novice gardener, but I've been doing a lot of reading over the past year and I really think, Terry, that you're taking on a straw man with the compost criticism. I agree 100% that compost is not the right solution for all plants. I'm in the process of converting a large chunk of my backyard to California native plants and everything I've read suggests they won't tolerate soil amendment. But the context of this discussion isn't California natives. The original description of the book highlighted the fact that it is aimed primarily at food producers. I'm sure there are food producing plants that don't benefit from compost but it certainly seems to me from the things I've seen that your average vegetable garden benefits quite a bit from adding organic matter to the soil. Terry, are you arguing that that isn't true (and the statement that compost is good for vegetable and general flower gardens is really all I take this blog to be saying) or are you arguing that there aren't enough caveats? Sure this blog could go through all the types of plants that don't benefit from compost but that seems quite impractical and I would argue that if you're a grower who is looking to grow something you haven't grown before it's your own responsibility to investigate the needs of that plant. I would never expect a single source to give all the answers for all locations and all plants. I have no problem with a blog that says something like "in general, for food gardens, compost is good."

[Terry]

One last comment scientific observations and anecdotal observations . . . .

Susan, you said "Jeff Lowenfels' slide show includes several examples of fields that are half compost tea-treated and half not with clearly better results on the tea side."

The essential question is, was a robust "scientific method" employed . . . . ?

- What was his null hypothesis in this (these) studies?

- Was his compost tea(s) sufficiently uniform in content and application rate across all replications? (For example, chances are there was at least some particulate matter in the tea, so was the tea sufficiently agitated during the application to insure that the particulates were evenly distributed across all plots?)

- Where test plots replicated sufficiently to eliminate enough variability so that treatment results could be effectively measured and statistically analyzed?

- And, finally, were his results published in a peer-reviewed journal?

I don't presume to know the answers to these questions, that's why I'm asking. And, maybe the Jeff's would like to chime in on the subject of valid experimental design that leads to the generation of valid research results?

My point here is that previously Elizabeth commented that this is a blog that offers nothing more than opinions. Yet, you, Susan, then ask why "pictures" of tea-treated plots don't count as experiments - which brings us back to the issue of, in my opinion, the risk of giving credibility to anecdote (and, like it or not, this blog has a huge amount of credibility - just ask all the media that has made mention of you) when scientific evidence may be lacking.

I don't mean this to be critical, or "uppity."

Rather, the four of you have put together, what I think is currently one of the most influential horticulture-related sites on the web. It's just that along with that influence, again, in my opinion, comes the ongoing responsibility to help your readers separate fact from fiction.

Again, keep up the great work!

[GrouchyLisa]

I used to comment just as Lisa, but I'm back to taking classes, and all them young whippersnappers have me grouchy as all getout. Anyways--I'm with Terry and Jeff Gillman. Even though it's partly a cheap appeal to authority, I'll stick with the scientists, at least in theory.

In reality, I'll hurl compost all over my shady back garden, because it's more "woodland" in nature. Besides, there wouldn't be enough left to hurl in the front xeric garden. In reality, I'll hurl some slow-release 12-4-4 lawn fertilizer all over my garden front and back (IF I remember) because I know that nitrogen vanishes from heavy clay, and that western soils are high in phosphorus and potassium. In reality, I'll toss some Osmokote into all of my containers, and probably a little organic fertilizer. IF I remember, I'll use soluble fertilizer on the containers from time to time. In reality, I'll toss down some Ironite around acid-loving plants that look kind of yellow and sickly. No, I won't calculate correct amounts. I'll just toss.

In reality, I won't make compost tea (never have) because I'm too lazy. In reality, I won't spray for any kind of bugs. I'll hang a couple of yellowjacket traps in a neglected corner if the little bastids turn up. In reality, I won't spray for weeds unless bull thistles turn up. And even then, I'll just use glyphosphate, once, and liberally. Since I live upwind of the nearest bull thistle plant seen last summer, it isn't terribly likely. In reality, I may or may not put out beer traps for the slugs--depends on how much damage I see.

I just can't be bothered with most "remedies" and organic "methods". I'm not growing things for commercial purposes. To be honest, I'm mostly growing domestic feline habitat. "Da Boyz" like to have a "jungle" to prowl.