Dirty Dozen?

Nobody in their right mind considers pesticides safe.  They are, after all, poisons which we have created to kill things, be those things plants, insects, fungi, rats, or whatever.  The idea that we could have foods with no pesticides on them is attractive.  Now I’ve got to admit that, as a general rule, I don’t think that the levels at which most pesticides are found on foods is concerning.  Our methods of detecting poisons are just too sensitive today and so we end up saying that a poison is “present” on a tomato or whatever even if it’s there at a harmless parts-per-trillion level.  Still, I won’t deny that I’d prefer it if there were no synthetic pesticides on any food.

A couple of days ago a report came out from CNN about the “dirty-dozen.”  http://www.cnn.com/2010/HEALTH/06/01/dirty.dozen.produce.pesticide/index.html This is a list of the twelve fruits and vegetables which are most likely to have detectible levels of synthetic pesticide residues.  Along with this list there is a suggestion that, when purchasing these fruits and veggies, you should select those that are organically produced whenever possible.  I don’t have a problem with this list being reported.  In fact, I think it’s a good idea to give people all of the information that we can about pesticides.  While I, personally, am not particularly afraid of conventionally produced fruits and veggies because of the synthetic chemicals which they may contain I appreciate the fact that others might be.  I do, however, have a major problem with the idea that organically produced fruits and veggies are necessarily safer than those produced with synthetics.  You see, organically produced food is not tested for residues of potentially damaging organic pesticides, and those same foods that are slathered by synthetic pesticides in non-organic growing systems are typically slathered by organic pesticides in organic systems, particularly if you’re dealing with foods produced using what has become known as “industrial organic production” which fill most of our large grocery stores with USDA Certified Organic Produce nowadays.  These organic pesticides may be present at higher concentrations than synthetic pesticides and may have similar effects on humans, and even worse effects on the environment than synthetics (though it depends on the exact pesticides used and how often they are used of course).

The myth that organic foods don’t have pesticides used on them is one that really needs to die.  No farmer, organic or non-organic, wants to use pesticides, and sometimes they can get away without using them.  Certain crops are rarely sprayed regardless of whether they’re produced organically or not.  Pesticides cost money and are dangerous, but when faced with the potential loss of a crop producers will do what they need to do to avoid losing their crop, and if that means applying pesticides then so be it.  Organic farmers may choose to use different pesticides, and they might wait longer before they spray (although often they spray sooner because the relative efficacy of their sprays are inferior to synthetic sprays) but let’s not say that organically produced foods are free of pesticide reside.  Just because we’re not testing for it doesn’t mean it isn’t there.

Duty Calls

As retirements have decimated our Horticulture Department’s faculty ranks, I find myself in the interesting position of teaching a course in small fruit production next fall semester. I’m working on the syllabus as was speak (hence this post).  If you’ve read my bio (“About Us”), you’ll see that this is not my bag.  But our students are clamoring for fruit and vegetable production courses, so someone’s got to do it. We are also  currently without on-campus vegetable faculty, if you can believe it. Though I know a few full professors that could pass as vegetables – HA!!!.

Anyhoo, I volunteered because I know just enough to be dangerous, and am willing to learn more.  I’ve been an avid home vegetable gardener
for years.
My partner has a Ph.D. in small fruit breeding and genetics, and I helped him with some experiments back in our grad school days (and his field sampling/taste trials made me doubt my specialization in ornamentals).  We now  have a you-pick blueberry farm where I’m learning the finer points of blueberry culture (the pH thing is a really huge deal).  All this vast experience obviously qualifies me to teach fruit production at the college level. I say this tongue-in-cheek, but many Horticulture departments are in the same boat, with early retirements used to meet budget shortfalls, compounded by hiring freezes (since 2007 here). Research staff, grad students, and hired instructors are picking up the teaching load and helping  the already-spread-too-thin teaching faculty.  I mentioned in a previous post about our brilliant state legislatures’ desire to eliminate urban Extension programs,  leaving only the agriculturally–related specialists and offices.

This is depressing on many fronts, but what bothers me most is that I feel we’re missing the boat – just when Horticulture is getting sexy again.  Think of how frequently this discipline is mentioned in the media, whether in the form of community gardens, safe food production, the popularity of native plants, sustainability, organics, etc….unfortunately, the writers/broadcasters rarely say the “Horticulture” word.  But horticulture is exactly what they’re talking about: small-scale gardening and the art and science thereof.  People want to do it, they’re thirsty for good information, and now, with the spotlight on us, we can’t meet their needs.

Nice tomato!

I can’t really think of an image appropriate to this rambling post, so will end this with a more cheerful photo of one of my tomatoes from last summer (variety is ‘Kellogg’s Breakfast’).

Visiting Professor guest post: Organic foods

There are lots of reasons consumers give for buying organic foods, but a few reasons are very common.  Among them is the notion that organic foods are better for you.  Really?  Are organic fruits and veggies better for you?  Depends on what you mean by ‘better for you’.  But as far as we know, the answer is probably ‘no’, especially if you’re buying organic fruits and veggies (F&V) at the store.  It might seem crazy, but there’s no good evidence to support the notion that you will be more healthy by shopping for organic F&V.  There are some complicated reasons for this, and some areas we aren’t quite sure about yet, but I’ll try to explain.

If ‘better for you’ means ‘fewer pesticide residues,’ you’re right.  But if you think ‘fewer pesticide residues’ means ‘better for you,’ that gets murky.  Why do we apply pesticides?  We do it to protect our food from pests and diseases.  It’s cheaper and more productive than destroying blight-infected tomatoes, individually wrapping apples in a protective barrier, or throwing away heads of cabbage with worms.  But why do those things matter?  It turns out we’re just consumers.  Two big things we look for when buying F&V are appearance and cost.  If a person has a choice between a spotty, more expensive apple and a uniformly bright and shiny lower-cost apple, he’ll probably choose the latter.  And which would be better, buying 2 heads of cauliflower because it’s pretty and low-cost (conventional), or buying one head because it has a slight cosmetic defect and costs a little more (organic)?  You guessed it; in terms of your health, it’s more likely that 2 heads are better than 1.  If that isn’t complicated enough, consider that there are no good long-term human studies concerning the health effects of pesticide residues ingested from food.  There’s no evidence that eating conventional F&V, even with the elevated risk of consuming more pesticide residues, is worse for you than eating organic F&V.  But there is evidence that eating more F&V is better for you than eating less.  So why eat less?

Some of the best health care in Minnesota comes from the Mayo Clinic.  What?  Who cares about the Mayo Clinic?  In Minnesota, we worship the Mayo Clinic. [undeserved pride] They represent some of the finest health care in the country [/undeserved pride].  And what does the Mayo Clinic have to say about pesticides on our food?  “Most experts agree…that the amount of pesticides found on fruits and vegetables poses a very small health risk.”

But what about nutrients—don’t organic foods have more nutrients or something good in them?  Maybe they do have fewer nitrates (which may be bad for you, especially if you’re too young to read this), but that really depends on how the specific growers use fertilizers.  Maybe some organic produce tends to have more vitamin C, but that can vary too.  And even if the organic tomato you’re eating has more vitamin C than the conventional tomato you passed up, is that physiologically relevant?  Does it matter to your body?  We don’t have any good evidence that it is.

Why am I being so down on organics?  Mostly because I like to play devil’s advocate.  I buy a lot of organic F&V.  There are some reasons to buy organics that may be more legitimate than “it’s better for me”.  Sadly, research seems to indicate that I buy organic F&V to make myself feel good for buying it, not because it’s actually better for me.  But in general, eating healthy means eating more fruits and vegetables.

Charlie Rohwer is a horticultural scientist at the University of Minnesota Southern Research and Outreach Center.  He has an MS from Michigan State University and a PhD from the U of M.  He currently studies vegetables and things that make them good for you.

A Dangerous Game

Every once in awhile I become infatuated with some idea and can’t stop for looking for information on it.  It usually starts when I want to find a good quote for a particular article or column that I’m writing and then ends up swallowing two or three days.  Well, it happened to me again yesterday and spilled over into today.  I’m currently finishing up a project with an old friend of mine from college who happens to be a political science professor at the University of North Carolina Charlotte.  We’re looking at certain environmental issues and the stances taken on them by both the left and the right.  Anyway, I wanted to make a point about biotechnology — that point being that when we graft two plants together we often get different chemicals in the plant which we grafted onto the rootstock than we would get if the plant were growing on its own roots.  This is because many chemicals can be translocated from the roots to the leaves or even the fruit.  Anyway, I quickly found a number of nice scientific articles to back up my statement, but I also found some other fascinating information about, of all things, tomatoes.  There are many plants related to tomatoes that tomatoes can be grafted onto.  For example, every spring our plant propagation class grafts potato roots to a tomato top.  Tomatoes can also be grafted onto eggplant (which is actually very useful because eggplant roots are very resistant to flooding unlike tomato roots).

While the above examples are interesting, they’re also relatively common knowledge among horticulturists.  Here’s the part that’s not common knowledge (or perhaps I should say here’s the part that I didn’t know about — I’ve been known to be ignorant of things that other people consider common knowledge before).  Tomatoes can be grafted onto tobacco, and, if they are, they will have nicotine translocated to their fruit — not a lot mind you.  Most of the nicotine ends up in the leaves and stems of the tomato plant, but still, why couldn’t a nicotine-laden tomato be developed which could help smokers kick the habit — in a semi-healthy kind of way?

I also found that tomatoes could be grafted onto jimson weed.  Big mistake there.  Jimson weed develops some pretty nasty alkaloids, and they end up in the tomato fruit.  So, if you eat the fruit, your done for.  In fact, I found an instance where 5 people were killed because they ate tomatoes grafted onto jimson roots.  I am now curious about what happens if you graft tomato onto deadly nightshade — but not curious enough to actually try it.

Organic or local?

I grew up on a small farm (30 or so acres) near Tacoma, Washington. We raised our own Herefords, I gathered eggs from my frizzle chickens, and we all enjoyed apples, plums and cherries from our fruit trees.  Neither of my parents were farmers by profession, though my grandfather owned a dairy farm in Oregon.  Eventually, my husband and I hope to move back to the family farm, if for no other reason than preserve it from the surrounding encroachment of houses.

I’ve been thinking about things I might do for fun or profit on the farm.  Home grown beef for sure.  A veggie garden – finally – on some of the only native soil left in the area.  We’ve got lots of options and the space to try them out.

Now back to the question in the title: organic or local?  Our family property has been managed gently since we moved there in the late 1960’s.  Nothing’s been added to the pasture soil other than what the animals deposited themselves.  We’ve had the apple trees sprayed yearly (a requirement because of apple maggot), but this is a targeted application with little affect outside the trees.  The cattle were never treated with hormones or other additives – they were about as free range as you can get.

I’ve heard from others that organic certification standards have become increasingly difficult to meet and some growers think they have become increasingly meaningless.  On the other hand, locally-grown products are becoming more available.

Is it time for a new standard – locally grown, with some requirements (e.g. soil tests) to demonstrate safety?

You say tomato, I say phytochrome

Yesterday I got an interesting email about a new product – a Tomato Automator.  Briefly, this square, red plastic disk slips around the stem of a tomato plant to suppress weeds and pests.  Most intriguingly, we’re told that the color “triggers a natural plant protein that makes tomatoes mature faster and product more fruit.”

Given this is a red product, it’s likely that the protein referred to is phytochrome (literally, “plant pigment”).  Phytochrome activity is maddeningly complicated to explain, so we’re going to keep this simple and refer (somewhat inaccurately) to “active” and “inactive” forms of phytochrome.  The active form of phytochrome exists when red light is predominant and encourages leaf expansion, chlorophyll development, and other characteristic of plants growing in full sun.  In contrast, the inactive form of phytochrome occurs when red light is reduced, either at night (when there’s no light) or in shaded conditions, where far-red light is predominant.  (Far-red light occurs just outside our range of visual perception but is absorbed by phytochrome.)

From a practical standpoint, this means a plant can “tell” whether or not its light environment is limited: both red and blue light are absorbed by chlorophyll, so a low level of red light means poor photosynthetic conditions.  Under such conditions, “inactive” phytochrome causes many plants to become etiolated (have abnormally long stems) in an attempt to outgrow the shade before it starves from lack of carbohydrate production.  In addition, this photosynthetically-poor light environment can also increase fruit set by redirecting resources to seed production rather than foliage  – perhaps a plant’s last effort to reproduce before it dies.

OK, now onto the useful application of this information.  Several years ago researchers investigated that effect of different colored plastic mulches on tomato production.  Again, to keep this simple we’ll just focus on the effect of red mulches.  It’s pretty much agreed that red plastic mulch reflects both red and far-red light, increasing not only red light but paradoxically the relative levels of far-red light.  Theoretically, this shift would cause tomatoes to put more resources into fruit production, and indeed some studies found this to be the case.

Unfortunately, the phenomenon is not consistent throughout repeated field studies.  Some of the other confounding factors are soil temperature (warmer temperature = more growth), insect and disease pressure (both decrease tomato production and are variably influenced by mulch color), and the fact that ethylene production (the plant growth regulator responsible for fruit ripening) is not controlled by phytochrome at all.

So are Tomato Automators worth the trouble?  Probably not, especially if you have many plants requiring many automators.

My Favorite Drug

I love coffee, but I’m not a big coffee drinker.  On average I probably consume a cup of coffee every week or two.  Why don’t I drink it more often?  For a few reasons: First, I’m too jumpy/jittery/nervous to begin with and I don’t need this stuff making it worse, second, it tends to upset my stomach if I haven’t had a meal beforehand, and third, while I like regular coffee, the stuff that I really love are those insane fru-fru coffee drinks that you can only get at specialty shops for five or six bucks — which seems like a waste of money to me.  As you may have guessed, at this very moment, I have an overwhelming urge for a vanilla latte and so, in lieu of that, I have decided to submit this post.

Anyway, as most of you know, coffee is a horticultural crop, and so are most of the other sources from which most of us obtain our (legal) chemical stimulants like chocolate and tea.  What most people don’t realize is that the stimulants in chocolate and tea are actually somewhat different than caffeine.  Chocolate does contain some caffeine, but its major stimulant is the closely related theobromine (which doesn’t actually have any bromine in it…).  Tea (which also has very low amounts of caffeine), on the other hand contains the stimulant theophylline which is, again, closely related to, but not the same as, caffeine.

What blows me away about caffeine is how toxic it is.  If caffeine were a pesticide it would need to be labeled as category 2 (there are 4 classes with 1 being the most toxic).  Its LD50 (in other words, the amount of this chemical that, if fed to a person, would have a 50% chance of killing him/her) is estimated at about 75 milligrams per pound that a person weighs.  According to Starbucks website, one of their tall vanilla lattes contains about that much caffeine, and so you could assume that a 150 pound person could kill themselves by drinking about 150 lattes (or 150 of the smaller cups of espresso from which the coffee is made).  Additionally, though findings are inconsistent, caffeine has been linked to certain cancers.  The current thinking is that it may affect hormone levels in the body which, in turn, influence hormone related cancers like breast cancer, etc.  This research is far from conclusive, but it is concerning.

OK, so here’s the thing that’s interesting to me.  There is a small but real contingent of people out there who want to ban the herbicide 2,4 D (I picked 2,4 D randomly – I could have picked Round-up,  Sevin, or any other pesticide – but I was thinking of summer, and so 2,4 D, the most commonly used turf herbicide, is what I chose).  I’m no fan of 2,4 D and would love to see it used less frequently than it currently is, but it is a useful herbicide, particularly in the production of grassy crops (like corn).  In lawns its overuse borders on the insane.

Opponents of 2,4 D would like to see it gone, in large part, because of its toxicity and potential to cause cancer.  And, indeed, there are some studies that show that 2,4 D has the potential to cause cancer, though these findings are inconsistent and ultimately inconclusive.  Additionally, in terms of 2,4 D’s LD50, it’s about 170 milligrams per pound that a person weighs – over two times LESS toxic than caffeine.  I’m not going to bother figuring out how much 2,4 D would be in an average glass of 2,4 D because, well, I’ve never been served a cup of 2,4 D before and hopefully I never will.  (If you’re curious as to how much 2,4 D would be in a cup of spray if you scooped it right out of the spray tank — then about 50 mg is a good estimate though it could be higher or lower depending on a lot of factors).

Anyway, this leads me to a ton of further questions, the most important of which is, without doubt, do anti-pesticide activists who fear the health dangers posed by 2,4 D drink coffee?

For those of you interested in these types of questions I encourage you to look over this article: http://www.marshall.org/article.php?id=73  It is posted on the website of a conservative group (which will probably alienate some of you and make others happy) – but it was originally published a number of years ago in a well respected journal and is one of my favorite articles ever in terms of getting the old brain thinking (Please don’t get the idea that I agree with everything in the article – I do not).  Bruce Ames, one of the authors, is what we call in academia a “heavy hitter” and so, even if you don’t agree with what he says, his words are well worth reading.


I’m not from the South, and so I can’t call myself a Southerner like Holly can, but I did spend 6 years in Georgia.  There are lots of things about it which I miss: winters which are more like a Minnesota fall, the almost disgustingly friendly people (OK, there was that one time that I was chased by a guy with an SKS assault rifle — but that was an exception — generally Southerners are the nicest people you could ever want to meet), and, especially, the food.  I love okra, I love grits, I love country fried steak, I love mustard greens, collard greens, fried catfish, sweet tea (which is starting to become popular here) etc. And for those of you thinking well shoot, you can get that at your nearest Cracker Barrel (which I frequent) — IT JUST ISN’T THE SAME.  One of the foods which I miss the most though — one that hasn’t found its way to Minnesota yet — is the boiled peanut.  For those of you who don’t know what a boiled peanut is, it’s a little piece of heaven that has been boiled in a tub of hot salt water for a long time so that, when you break open the peanut’s shell, now the texture of watery cardboard, the seeds inside are soft, warm and, you guessed it, salty.  So, why am I telling you this?  Because I can’t suppress my excitement any longer.  Tom Michaels. a good friend of mine who is a transplant from a Canadian University where he worked on bean breeding, and I recently were talking about boiled peanuts and he told me that he has a peanut variety which will grow here in Minnesota without too much trouble and which is can be used to make hot boiled peanuts.  So I’m in the process of finding excuses to plant this critter — I’m going to plant it between rows of trees, in grass plots, in vegetable gardens — and then I’m gonna harvest them all and make hot boiled peanuts through the entire winter next year!

Eat your veggies! (But not the arsenic, or the chromium, or the lead…)

vegetables_jpg.jpgThe last few years have been a perfect storm for the resurgence of home vegetable (and fruit) gardens.  Grapevines are trellised along sidewalks, herbs replace the grass in parking strips, and tiny gardens of carrots and lettuce are shoehorned into any available spot.  It’s all good  – but we need to be particularly careful about what those plant roots might be taking up along with nutrients and water.


1)  Contaminated soil.  Many urban (and suburban, and even rural) soils are contaminated with heavy metals, pesticides, and/or industrial wastes.  Lead is commonly found in soils near roads (from the old leaded gasoline we used to use) or from old lead-based paint chipping away from houses.   Arsenic is a very real problem in North Tacoma soils, for instance, thanks to the smelter that operated there for decades.   Overuse and incorrect use of home pesticides will leave residues in the soil for years.


2)  Contaminated compost and soil mixes.  Many of the same contaminants mentioned above can be found in unregulated composts and soil mixes.  (More on this topic here.)


3)  Treated lumber.  The old treated lumber (CCA = copper, chromium and arsenic) is no longer being sold, but it’s out there.  These timbers should not be used around vegetable gardens, as they will leach their heavy metals into the soil.  Vegetables vary in their ability to take up and store these metals.  (More on this topic here.)  Likewise, rubber mulches may leach unwanted chemicals into the soil and should not be used around food plants.  (More on this topic here.)

   garden_jpg.jpg    treated%20lumber_jpg.jpg

What can you do to avoid these problems?  A few things are quick, easy and cheap:

1)  Have your soils tested.  I’ve mentioned this in an earlier blog on urban soils.  It’s the best way to find out exactly what you have in your gardens – the good and the bad.

2)  Use only certified composts and soil mixes.

3)  Plant in containers if your soils aren’t safe for food.  This is especially easy to do with perennial herbs, which can be kept like any other container plant on your deck or porch for years.

4)  You can also replace the soil in your vegetable garden.  This isn’t quick, easy, or cheap, but is a solution for some people.