jeffgillman003

What Happens to the Horticulturist?

A couple of weeks ago I had the opportunity to talk with a professor in the agronomy department who’s going to be retiring very soon. We talked about education and field trials, corn and trees, and then we started talking about the future of our departments. Both of us are concerned that this generation of horticulturists (and agronomists—but I’m just going to deal with horticulture here) will be the last.

Over the last 10 or so years we have been losing horticulture departments. Because of smaller budgets colleges and universities have combined hort departments with other departments to save money. But I don’t see this as a major problem, after all, a rose by any other name would smell as sweet (OK – truth is I don’t know many sweet smelling horticulturists). Horticulturists can be in departments besides horticulture and still do their job…But what is the job of a horticulturist at a university?

There will be all kinds of opinions on the “real” job of a horticulturist, but I believe that a big part of being a horticulturist is being a generalist – knowing a little about a lot of different things – insects, plant disease, soil. We’re a little like a general practitioner who can take care of basic stuff and then refer the client to a specialist if needed. Though most of us work with a particular type of crop (historically horticulture was split into 4 large groups – floriculture, fruit, vegetables, and landscape horticulture), horticulturists generally know enough about other crops so as not to make too much of a fool of themselves if they talk in general terms. We know how plants work, and we know how the environments around them work to help them grow. We are, in many ways, applied ecologists who are concerned about landscapes and the production of what many consider “minor” crops (at least compared to corn and soybeans!).

The biggest problem, as I see it, is that we are not hiring, or training, the number of horticulturists we once did. In colleges and universities a premium is placed upon hiring faculty members who can acquire big dollars through federal grants. The government likes “sexy” research which, right now, includes things like genetic engineering and biochemistry. The government is open to having this work done on crops like apples and onions, or even nursery stock. The problem is that generalists don’t tend to have the specialized knowledge in genetic engineering or biochemistry to do the work. Hence, a biochemist or molecular biologist is hired and, hopefully, gets the grants the university needs. But, in my experience, rarely do they really understand the crops they’re working on in terms of actually growing it. Some do of course, but in the cases where they do it tends to be after the fact – in other words they learn about the crops after they begin working on them and their knowledge is often very basic. I suppose this is OK, but to me it is sad that we’re not hiring what I consider true horticulturists anymore. And, because we’re not hiring true horticulture faculty we’re not graduating many horticulturists from our graduate schools either. Sure, we’re graduating molecular biologists and biochemists – and even a few breeders (who very often are horticulturists) – but these students may or may not leave a university with knowledge of “horticulture” as a whole. And if we don’t start hiring more horticulturists what will happen? Who will teach our introduction to horticulture course – or will horticulture just fragment and we’ll all need to go looking to specialists. I don’t know, but it bothers me.

One Of The Best Pictures I’ve Seen

Yesterday Jeff Hahn, an entomologist here at UMN (and author of the book Insects of the NorthWoods — a great field guide for Wisconsin and Minnesota), sent me a picture which reminded me of the dark ages and the methods that leaders of the past used to scare and intimidate their subjects as well as possible invaders.

This picture came to Jeff by way of Terry Straub, a Program Coordinator for Master Gardeners in Hennepin County. Terry can’t remember where he got it from — The reason I’m mentioning this is that I’d love to give the person who originally took this picture credit for their brilliant (and somewhat disturbing) photo.

Vinegar: A Garden Miracle!

I’ve been working with homemade garden remedies in one context or another for about 10 years now. As someone who has spent days searching for odd cures to garden problems I consider myself qualified to say that, of all of the remedies I’ve seen, vinegar seems to be the product with the most (supposed) uses. You can kill weeds with it, as well as plant diseases and insects. You can also use it as a fertilizer or even to acidify your soil. It’s amazing! But which of these uses are real and which are just someone flapping their jaws?

Vinegar as an herbicide: White vinegar which is about 5% acetic acid and does a nice job of burning the tops of plants, but not their roots – so a larger weed will live right through a spray even though it will look bad right after the spray. You can buy 20% acetic acid. It works faster, but it has essentially the same problem killing larger weeds that that 5% acetic acid does. Besides efficacy issues there are safety issues also. I’ve used 20% acetic acid and I think that this stuff is too dangerous for the average person. A little in the eyes could cause permanent injury. Just a little whiff of it is enough to make the nose start running (in other words it’s not good for mucous membranes).

Vinegar as a disease control: What a great idea! Spray something that kills plants onto your prized petunias to control disease! OK, when you use vinegar as a plant disease control you do use a lower concentration which shouldn’t hurt the plant. But vinegar has never proven to be particularly effective at controlling plant diseases.

Vinegar as a fertilizer: Nope, doesn’t work. Acetic acid only contains carbon hydrogen and oxygen – stuff the plant can get from the air. The other things that may be in vinegar could be good for a plant – but it seems an expensive method of applying an unknown amount of nutrition.

Vinegar as a soil acidifier: This is one that I’ve seen a lot – and so I tried it. In a nutshell, it just doesn’t work that well. It takes a lot of vinegar and the pH change is brief at best. Use something like sulfur instead.

So to summarize, despite a lot of recommendations, the only thing that vinegar has really proven to be good at is killing weeds – and then only if the weeds are young.

Getting Stung Can Be Fun!

Today I was reading a review of Amy Stewart’s new book Wicked Bugs and noticed the glee with which the reviewer noted that stings of various insects have been rated on a four point scale. Having read Amy’s book I can wholeheartedly recommend it, but in terms of the stings I thought, what the heck? Let’s see if I can impart some glee to our readers by taking a look at the pain that stings cause (I think it’s kind of like highbrow slap-stick). So here is a brief review of sting science over the years.

First of all, scientists have known for some time that the pain of an insect (or spider) sting is not necessarily correlated with the amount of damage which the sting causes, so scales that have been used to assess the pain of insect stings do not necessarily correlate with the amount of damage done by the sting. The stinging critter is not actually trying to kill the person which it stings (though stings may certainly kill smaller critters), rather, it’s trying to keep them away from itself and its family.

The first person in modern history to actually go to some trouble to figure out how badly a sting could hurt you was William Baerg who, from what I can tell, was dared by a colleague to get himself bitten by a black widow around 1923. He did so, but since the bite didn’t hurt too badly he had the spider bite him again the next day. After this second bite he recorded his reactions – including difficulty in breathing and talking. Apparently a masochist, Baerg continued to allow himself to be stung by scorpions, centipedes, and tarantulas — supposedly in the name of science. And here I’ve gotta say that, as a scientist, you need to set some limits. Actually the stings must not have affected Baerg too badly – he lived from 1885 to 1980.

Following in the footsteps of Dr Baerg, another scientist, Justin Schmidt, has been sting by a tremendous variety of venomous insects (I’ve heard that it’s over 100 different species) and has actually developed a scale to sort out which hurts the worst. The scale runs from 1-4 with a 4 being “debilitating” and 1 being a “spark”. Apparently he never gets stung on purpose – but dang, you can’t be trying too hard to avoid the stings if you’ve got that many species on your “been there done that” list.

Dr. Schmidt published his first paper on the painfulness of stings in the early 1980s. His work was soon followed by a paper published by Christopher Starr. The name of this paper was “A simple pain scale for field comparison of Hymenopteran stings”. This paper includes a list of insects and the level of pain which they cause with their sting – basically following Schmidt’s work – but Starr makes sure that he has at least two data points before he lists the pain which the insect causes. He also makes a point of noting when the insect was induced to sting instead of having the sting just happen. According to his chart he was stung by 34 (if I counted right) different insects, and of those stings only 6 were induced. Obviously this guy didn’t take his work as seriously as Baerg or Schmidt!

Most of the stings that we’re accustomed to – bees and wasps – are around a 2. There are a few at a level of 4 – probably the most notable is the bullet ant.

Starr ends the conclusion section of the article by listing 6 important rules for grading stings – I found them fascinating – so here they are:

Reports should only be made by adult observers in good health.
Disregard all stings accompanied by allergic reactions.
Reports should not come from observers who are rarely stung. This is to avoid mixing pain and novelty.
Reports should be based only on events in which a very small number of stings are received at once.
A ranking should never be based on just one sting. Although individual social wasps probably sting rarely (I suspect that most never do), so that significant day-to-day variation in venom volume is unlikely, uncompleted or grazing stings are uncommon. It is not known to what extent the regular use of the stinger by solitary wasps causes variation in venom delivery.
Reports on stings received through free attack by the insect (volunteer stings) are preferable to those deliberately induced by holding her between the fingers or against the skin (induced stings). We are not always so fortunate, though, to be attacked by those species of special interest……[deleted for brevity]

Our visiting GP takes on fertilizers

Like many readers of this blog, I’m like a kid in a candy store where plants are sold. I try to justify the extra cost of a large annual pot instead of a scrawny 4-pack, or I imagine I’ll find room for that lime green Heuchera and my wife will learn to love it. But unless I keep my blinders on and stick to the shopping list, I’ll probably leave with a fertilizer. This year, I’ve purchased 12-0-0, 5-6-6, sulfur, and some 5-1-1 liquid. Those go with my 6-9-0, 11-2-2, 9-0-5, 2-3-1, and 4-6-4. I can explain why I ‘need’ each one. I have a decent idea what my soil is like because I’ve had it tested (though I’m due for another test). But I’ve always questioned how those bags of fertilizer can know exactly what my garden needs. The rates listed on the bag imply they’re universal under all circumstances and will give great results if the directions are followed. Is that true? And at what cost?

For example, 2 of the bags are listed as ‘lawn’ fertilizers (the veggie garden doesn’t care about that though). But if I apply these to my lawn at the rate listed and 4 times per year, I’m adding 3-4 pounds of nitrogen per 1000 ft². That’s a reasonable rate if I irrigate and bag my clippings, but I don’t do either. Therefore, I only need ~1 pound of nitrogen, not 3 or 4 (see this publication for more info). I just saved myself some money by disobeying the bag. That extra nitrogen isn’t useful for making MY lawn healthy.

One of my fertilizers is labeled ‘tomato’. If I do exactly as the bag tells me for tomatoes, I would be applying the equivalent of 400 pounds of nitrogen and almost 500 pounds of phosphate per acre. So what? Well if I look at a guide for how to grow tomatoes commercially, I’d notice that the recommended nitrogen rate is 100 to 120 pounds per acre, and phosphate is 0 to 240 pounds per acre. Yes, those are commercial guidelines, but they shouldn’t be too far off from garden recommendations. And of course, recommendations should always be based on soil tests. But 4 times the N and 2 to infinitely more times the amount of phosphate than is required? That’s likely a waste of money at least. And yes, those recommended guidelines are real: you CAN grow food without adding phosphate or potassium-containing fertilizers. If the plants you’re growing don’t need much and your soil has plenty, you don’t need to add any.

Say I’ve got an acre of onions (Fig. 1; not quite an acre). One of the bags of fertilizers, were I to follow its instructions for fertilizing ‘vegetables’, tells me that I should add 100 pounds of nitrogen and 120 pounds of phosphate and potash at planting (per acre), followed by half that partway through the season (next to the row). The commercial production guidelines tell me that the nitrogen rate is similar to what the bag of ‘vegetable’ fertilizer says, but I actually need about 7 times less phosphate and potash (based on my soil test results; I have quite a bit of P and K already in my clay-loam soil). I don’t want to add stuff my soil doesn’t need, so I use my shelf full of bags, a scale for weighing pounds of fertilizer per cup, and some math to come up with a custom fertilizer regime that suits my soil and the onion’s needs (see Table 1, and remember that the numbers are for MY soil, not necessarily yours).

One problem with using extra fertilizer may be in the extra cost (wasting nutrient the plant won’t use), but that depends on what fertilizer it is and how much it costs. Another problem may not be immediately apparent, and that is nutrient deficiencies. Too much phosphorus can cause zinc deficiencies, for example. Excesses of some nutrients can create greater chances for pest and disease problems. One big problem with using too much is the potential for these extra nutrients to go where they shouldn’t be, like in groundwater, rivers, lakes, and streams. And as Jeff has mentioned, phosphorus fertilizers won’t be around (cheaply) forever.

Do the work of figuring out what kind of soil you have and what’s in it, what your fruits and veggies need, and what kinds of fertilizers can do the job for you. Heck, you can even organize your fertilizers based on “cost per pound of nitrogen” to see where the best bang for your nitrogen buck will be. But none of us are THAT obsessed about our fertilizers, right?…. [$ per bag / (pounds per bag * (% nitrogen/100))].

As a reminder, the numbers on your fertilizers are percent nitrogen, phosphorous (as ‘phosphate’, P₂O₅), and potassium (as ‘potash’, K₂O). One cup is 16 tablespoons, and an acre is has length of one furlong (660 feet) and width of one chain (66 feet), or 43,560 square feet. Side rant: metric rocks.

Bt in the Bloodstream!

Over at my favorite blog (besides this one of course!) Garden Rant, Amy Stewart posted about exploding watermelons — which Linda blogged about below — and about how Bt from genetically engineered food had found its way into our blood stream (and the bloodstream of unborn children). Sounds pretty scary doesn’t it? I’m not going to tell you it isn’t a little troubling, because it is, and I absolutely do not think this finding should be disregarded. But the truth is that I’m not too worried about Bt in the bloodstream for the following reasons:

1. The world’s ending on Saturday anyway, right?

2. It’s impossible to tell from this study where the Bt toxin came from — I do think it probably came from transformed crops — HOWEVER, as scientists we can’t make that assumption. We eat Bt all the time EVEN IF WE EAT NO TRANSGENIC CROPS because this bacteria is found all over the place. I would have liked to have seen testing between people who eat transgenic food and people who eat no transgenic food.

3. The Bt toxin is extremely specific in terms of what it affects in an insects gut. It’s unlikely (but not impossible) that it would react with anything in our bloodstream (or an unborn child’s bloodstream).

4. There are arguments over whether transgenic crops are sprayed more or less than than non-transgenic crops — but for insect control transgenic crops are generally sprayed less — and non-transgenic crops are sprayed with some seriously nasty stuff including nerve toxins. If I get to pick my poison I’ll go with Bt any day.

5. As a rule you should NEVER worry until a second study confirms the findings. This paper is important enough that you can be sure that within a year someone else will try something similar. If the findings hold my concerns will increase somewhat.

6. Finally, the dose makes the poison. Bt has been fed to various mammals for years to determine the effects that it has on them — and it generally has little effect, even over long periods of time. These animals, obviously, had the toxin in their blood (just because it wasn’t tested doesn’t mean it wasn’t there).

It should be no surprise that when we eat something with a toxin in it, that toxin gets into our blood. When you eat garlic — toxins from the garlic get into your blood. When you eat hot peppers — capsaicin (an insecticide) gets in your blood. When you drink alcohol — you get the picture. Is it bad for things to be in the blood? It depends entirely upon the thing and the concentration. This article talked about fetal issues so lets use a fetal example — Aspirin is considered a bad idea during pregnancy — it can get into the unborn child’s bloodstream. However, low doses of aspirin can reduce risks of pre-eclampsia. By the way, a chemical very similar to aspirin is also known as a fungicide….(actigard).

So, there are my reasons for not being too worried. Could I change my mind — YES. Could I be wrong — YES. BUT as a scientist who reads a lot of what I’ll call “reactionary/radical articles” I have my doubts when I read about the next thing that’s going to kill us all. If we responded to every troubling article we’d never leave our houses. BUT there’s always that one important article that warns us about something real — and we need to be on the lookout for it. My reaction to the Bt threat — this isn’t it — but time will tell whether I’m right or wrong.

When Trees Don’t Know They’re Dead.

Last week a neighbor of mine called me up to ask how likely it was that their 4 year old (or so) crab apple tree was dead. Sometime over the course of the winter cute fuzzy bunnies had decided that the tree’s bark was tasty and decided to eat it. Naturally they ate it all the way around the circumference of the tree with the exception of a strip about an inch wide. At this point you’re probably asking yourself why the neighbors suspected the tree might be alive. The reason they were calling me was that the tree was leafing out– so they figured that maybe the tree would make it — that maybe, just maybe, it wasn’t as bad as it looked. My answer — Sorry, the tree is dead, it just doesn’t know it yet. As a rule of thumb you can have up to a third of the circumference of a young tree girdled and the tree has a decent chance of growing out of it. More than that and, though the tree might live for a few years, you’re dealing with so much damage to the vascular tissue that you’re just putting off the inevitable by not cutting it down. A tree with as much damage as my neighbors tree had was just going through the motions.

When bark is eaten what is destroyed is the phloem — the tissue which carries the carbohydrates made by the leaves down the plant’s stem. The cambium — which creates new phloem and xylem — is also destroyed. But the xylem — the innermost tissue which transports water and nutrients up the stem — is left largely intact. So girdled trees will flush out in the spring (using resources provided by the xylem), perhaps even two springs, but ultimately the tree will succumb.

But there is an up-side! Girdled trees will be under a lot of stress. Stressed trees tend to flower heavily — so enjoy the show first, then cut down the tree.

This ‘n That

Grading finals, looking at roots, and planting seeds is consuming my time this spring, but I have just a few things to share today which might be interesting.

So, as those of you who follow this blog know, I love peanuts. This year we’re planting out a bunch of new varieties, a few of which are extremely interesting. Believe it or not there are not only red and pink peanuts but also black, white, and mottled peanuts. We have these on order — when they come in I’ll post a picture. When we introduce Minnesota Boiled Peanuts at the State Fair in a few years (that’s the goal anyway) the plan is to introduce a wide variety of really unique looking peanuts. Fingers crossed they can live here!

Here, at the University of Minnesota, we do a really great job of telling people that, when they fertilize their grass, they should keep the fertilizer on the grass and not on the sidewalk — SO WHY CAN’T THE UNIVERSITY TEACH THE KIDS WHO APPLY THE FERTILIZER TO THE UNIVERSITY’S LAWNS TO KEEP THE DARN FERTILIZER OFF OF THE PAVEMENT?!? Last week as I walked in I heard a crunching sound coming from my feet. When I looked down there was a little pile of fertilizer on the sidewalk.

Believe it or not, judiciously fertilizing your grass actually helps prevent fertilizer run-off. That’s because grass with a weak root system (as occurs in the typical lawn when you don’t fertilize at all) won’t be able to hold the soil as well — so you get more erosion. So do fertilize your lawn, just don’t go nuts.

About that whole tree in the lung thing which I posted last week? Yeah — It’s BS. How do we know it’s BS? No obvious roots on the tree and the tree’s needles were green (you don’t get green plants without sunlight). Personally I think this is some kind of odd cry for attention, but I guess it’s possible that the guy swallowed a cutting while he was shearing/pruning trees. HOWEVER, there are documented cases where seeds will germinate in a persons lung — Usually the person has a compromised immune system.

A word about GMOs from our visiting GP

I gave a talk to a group of gardeners last year about vegetable and community gardening. There was a wide variety of gardening experience represented, but one statement from a seasoned gardener bothered me a bit. And I think my response bothered him a bit too. I haven’t thought much about it until recently, when a high school English teacher I know told me a student expressed similar ideas in her class. The erroneous idea from my audience member was this: our tomatoes are being poisoned with ‘germetically modinified’…something something. The arguments have lost me beyond that (because there aren’t any). And really, there hasn’t been much talk about sex on this blog recently, so that should be remedied too. Therefore, I would like to take the platform offered by the Garden Professors to talk about plant breeding.

Fig. 1: Jaune flammee, which has at least one gene from at least one of its parents that causes the fruit to have very little lycopene.

Conventional” breeding is when a plant breeder selects parents and offspring and tests them for desirable characteristics (traits). It works the same way as breeding works in nature, except that we humans have a goal we’re working toward. Firm, 5-oz, disease-resistant, crack-resistant tomatoes, for example. In nature, the offspring that survive and reproduce the best in a given environment are ‘blindly’ selected and tend to stick around (Darwin, 1859). Male (sperm) cells are transferred to female (egg) cells by a plant breeder, or a bee, or the wind, or a beetle, or a fly or bird or bat or moth (etc.). The sperm and egg fuse to form an embryo, which grows to become what we’d call a plant. In both natural and artificial selection of tomatoes, no non-tomato DNA has been added, and no tomato DNA has been removed. By the classical definition of ‘genetic modification’, there has been none. I suppose this paragraph was only incidentally about sex, and probably a disappointment to some. Sorry.

Fig. 2. Tainan, a tiny heirloom

The confusion of the issue may lie with the Flavr Savr tomato. This was developed (yes, genetically modified) in the mid-90’s to resist softening during ripening. It has a couple bits of manufactured DNA in it to make this possible. The Flavr Savr is no longer grown or sold in the marketplace (that was SO 1990’s), and to my knowledge, no other transgenic tomatoes are either.

Fig. 3. Rutgers, historically much-cultivated and like all other tomatoes we can buy, bred conventionally.

Confusion may also lie with the plant hormone ethylene. Ethylene is made from incomplete combustion of fossil fuels, but it’s also made by plants. Keep your bananas away from your carnations, right? Bananas make ethylene gas, which causes carnations and snapdragons to senesce (die). Tomatoes make ethylene as they ripen. If you harvest tomatoes a bit early, but not too early, they are hard enough to ship but will still turn red later. If you expose these pre-ripened tomatoes to ethylene gas, they will ripen more quickly and uniformly. That’s what happens to a lot of the tomatoes in our stores. They are not genetically modified, they are treated with a plant hormone. That’s not unusual at all. Ethylene is used to ripen bananas, and to help make cucumber seeds (by eliminating male flowers from female parents). It’s used in growing ornamental plants quite a bit too (but not as much as many other hormones, and especially hormone inhibitors).

So please, if you are someone who tells anybody who will listen that the tomatoes in the store are GMOs, stop it. They’re not.

It’s That Time of Year

This time of year is tough for folks who do work with plants. It’s the happiest time of year because the world is turning green again, but it’s also the busiest time of year because we need to be inside teaching, outside planting, and also on the road since spring talks are finishing up. Honestly I’m having trouble finding an hour to myself to work on writing up papers and articles.

That said, let me leave you with something that’s been bugging me the last few days (based on an article I read a few years ago). If a person were in inhale a small seed, would it grow into their lungs?

What do you think? Real or BS?