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Over-Interpreting

One of the things that scientists need to be able to do is to figure out what the research that they conduct means without over-interpreting it. This isn’t as easy as it seems, for example, if a particular pesticide at a particular dose kills mice, then should it also kill humans? Without testing we really don’t know – though we certainly have suspicions. If we allow our suspicions to take over and we say that, based on the mouse data, the pesticide necessarily does or doesn’t affect humans then we’re over-interpreting. Most (dare I say all?) scientists have been guilty of over-interpreting their results – or the results of others — at one time or another in their careers. It’s a hazard that comes with the job. Unfortunately it’s a hazard that comes with journalists jobs too — often over-interpreting what scientists say. Recently I had the opportunity to see an online lecture (a TED lecture) on this very topic and thought it was worth sharing.

Planting Edibles in Cities

The snow has just started falling and I’m already thinking about what I’m going to be planting next spring. Most of my plantings won’t be at my own house, they’ll be out in the cities of St. Paul and Minneapolis. We’ll be looking at all kinds of fun stuff like growing trees in various new types of containers, adding compost to planting holes in different circumstances, and even pruning methods. But one of the big things that we’re starting to look at are new trees for the urban environment. Cities have always spent time considering what they plant, but with the emerald ash borer ravaging the Midwest, now they’re thinking even harder. And because of the local food movement, suddenly the cities are at least considering trees like apples and hazelnuts on a trial basis (sure, there are some places that use them here and there, but they’re less than common). Of course, if this movement stalls, the cities would be upset at having so many “messy” plants around (that’s their big concern about edibles right now), but I don’t think it will. I’m actually pretty optimistic about using fruits and nuts on public property. Sure, some plants will fail because they get too many diseases or insects, or because they’re weak wooded, but some will make it too. I think hazelnut has a great chance in the right place (it would be too bushy for most boulevards….). Do any of you have a favorite edible that you think might work well in a city? Let me know, maybe we’ll try it!

Closing the loop

Just a short post today as I am participating in an Extension planning meeting for most of the day. One up-side to the meeting is we are meeting and having lunch at Brody Dining hall here at MSU. If you’re around my age and attended college in the 80’s, the thought of eating at a dormitory dining hall might elicit memories of a hair-netted cafeteria lady glopping amorphous slop on your tray next to the mystery meat of the day. Boy, how times have changed. Today, the quality of dining hall food is point of competition for universities angling for students. The Brody dining center is set up like a food court, daily choices for students include a fresh salad bar, southwest food, sushi, made to order pizza, home-style comfort food, even kosher food.

The dining halls are also part of MSU’s sustainability initiative. Food wastes from the dining halls are collected and sent to an anaerobic digester and composted at the MSU Student Organic Farm. The compost is used at the recently completed Bailey hoop-houses on campus to produce salad green and herbs for use in the dining halls, providing a closed-loop system. Is the food produced in the hoop-houses going to make the dining halls completely self-sufficient? Probably not in the foreseeable future. But they do provide a good opportunity to promote horticulture. The project has generated numerous press articles and there are posters around the dining hall highlighting the project. In an age when many bemoan the public’s disconnect between farm and fork, the Bailey GREENhouses remind students, especially those that might not think about it otherwise, where their food comes from.

Does fertilization increase insect herbivores?

Always fun when you find a research paper that confirms what you’ve suspected all along. I ran across a paper last week in the Annals of Applied Biology entitled ‘Fertilisers and insect herbivores: a meta-analysis’ (Butler et al. 2012. Ann Appl Biol 161: 223–233). I’m interested in the topic because in recent years a dogma has emerged that if you fertilize a landscape tree it will be immediately devoured by insects. In this study the authors conducted a meta-analysis (basically a compilation of studies on a given topic and then combining and analyzing the aggregated results) and looked at dozens of studies of the response of insect herbivores to fertilization to answer the question, does fertilization increase insect damage? The answer was absolutely no surprise to me: It depends.

What does it depend on? First, what type of insect. Secondly, what kind of fertilizer. For example, fertilizing with nitrogen greatly increases populations of sucking insects. This makes sense when you stop to think that aphids and other sucking insects have to consume a lot of phloem sap –which is essentially sugar water – in order to get sufficient nutrients. Nitrogen fertilization did not significantly increase populations of chewing insects, however. This could be related to off-setting effects of improved nutritional quality of leaves versus increased presence of defense compounds or leaf toughness. For other fertilizer elements Butler et al. found that phosphorus decreased insect populations in 2/3^rd of the studies (14 out of 21) and that potassium decreased insects in 7 out of 10 cases. As with nitrogen only, complete fertilizers (NPK) tended to increase insect populations, especially for sucking insects.

I should hasten to point out some limitations of the study as it relates to tree fertilization. First, of course, is the British spelling of fertilizer. Second, the study mainly dealt with fertilization in agronomic crops, not trees. Lastly, the authors only included studies on insect adults. In many cases insect larvae, not adults, are the most damaging life stage, especially for insects that affect trees. Nevertheless, the study highlights the difficulty of making generalizations when discussing host stress and insect interactions. In addition to type of insect and type of fertilizer, we could have added nutritional status of the plant before fertilization to the ‘It depends’ list. My rule of thumb is that trees shouldn’t be fertilized unless a problems is noted by visible symptoms, a soil test, and/or a foliar test – and preferably by more than one of these.

Bottom line: Before you buy into the notion that fertilizing a tree is going to increase insect problems make sure you know what type of pest you’re dealing with, what type of fertilizer and the current nutrient status of the tree.

How Can Natives and Exotics Possibly Coexist?

Natives vs. exotics. We’ve heard that before haven’t we Bert? Well, here’s an interesting little nugget published recently in the journal Ecology Letters. Exotics and natives are different, and their differences allow them to coexist. In this study exotics were superior to natives in terms of growth, but were fed upon more by herbivores. Interesting. Of course there are lots of different types of exotics and natives, but the plants that these researchers looked at had been living together for about 200 years. I think that’s something that the invasive extremists and apologists consistently forget – until relatively recently the average person didn’t spend that much time thinking about native or exotic, and yet the world never turned into a desert and neither the natives nor the exotics disappeared. I’m not saying we shouldn’t think about native vs. exotic differences at all, just that sometimes we concentrate on this distinction too much. Plants tend to be able to fend for themselves.

Why oh Why? Christmas tree edition

Hope everyone has had a chance to digest their Thanksgiving meal and is spending a productive day at work shopping on-line. My daughter and I enjoyed one of our Holiday traditions this weekend and brought home a Christmas tree from a local choose-and-cut farm. This was followed by another tradition at our house known as the “Annual cursing of the Christmas lights.” Seems like no matter how careful I am when I put away the lights when we take down the tree, they are always a mangled mess the next year.

Christmastime is also time for another ‘Why oh why?’ As in, why do people make such a big deal out of watering their tree? Working in Extension with Christmas trees, I’m glad that we’ve gotten the word out and people are concerned with keeping their tree watered. But is it really that hard to put water in the stand? I use a watering can with a long stem and it seems to work fine. Let’s look at some of the devices people have come up with water Christmas trees. I’ve rated each on scale of 0 to 4 watering cans.

The tree IV. I’ve mentioned this one on the blog before. The theory here is that the tree will suck up water from a reservoir you attach to the trunk. Trunk injection is possible with conifers but requires pressure and resin quickly fills the hole. 0 cans.

The watering cane. OK, maybe you’ve got back problems and bending over with a regular watering can could be an issue. 4 cans.

Water funnel system. I’m not sure the video convinced me this is faster and easier than the watering can. 2 cans.

Water reservoir cleverly disguised as a package. Assuming the issue is you don’t like to bend over and put water in the stand, I don’t see where bending over to put water in a fake package is a big improvement. And what happens if you forget which package is which? 2 cans.

Funnel cleverly disguised as an ornament. Gets around the bending over issue, but can you really hide the tubing? 3 cans.

Christmas Vacation anti-transpirant. According to the advertisement you can put this stuff in the first time you water the tree and then you are good to go for the next month. The same product is sold as ‘Stasis’ and is used to protect bedding plants from wilting during shipping. The theory is that the product induces stomatal closure by increasing abscisic acid levels. I’m withholding judgment on this one until I see some data one way or the other, but to say I’m dubious is an understatement.

Keeping a Christmas tree hydrated is like most things; you can’t go wrong with the tried and true. A fresh tree that is kept well-watered will retain needles for weeks and is very unlikely to be involved in a tree fire. A tree this is allowed to dry, on other hand, is another story. So before depending on a gimmick to keep your tree watered ask yourself if you’re willing to bet your house on it.

Thanksgiving

Yesterday was the day before Thanksgiving. In my plant production class I always set up a short lab for Wednesday afternoon so that students can leave early and get to wherever they need to go (hopefully to see family). As usual, I got to lab a little early so that I could get the students going right away. Waiting for me there was one of my students.

Earlier in the year I had told the class about commercial mycorrhizae and how the beneficial spores that you think you’re buying are usually dead when you purchase the package. Well, this student wanted to check it out, so, unbeknownst to me, he purchased some mycorrhizae and placed them into a petri dish with a special nutrient mix to grow these fungi (he works in a lab which has this kind of material available). He came to lab early to tell me about his results.

As a teacher it’s easy to get discouraged in a classroom. Sometimes it’s tough to tell whether the students are listening and I wonder if I’m getting through. But then a student goes and does something like this and it’s all worth it.

The results of his little test don’t really matter (though they did confirm what I’d told the class), what matters is that the student heard what I’d said and went to the trouble to test it for himself.

So this Thanksgiving I’m thankful that I’m fortunate enough to witness and take some small role in the intellectual curiosity of students.

Happy Thanksgiving Everyone!

PS: Just so everyone knows, The Garden Professors are becoming much more active on Facebook. Just search for The Garden Professors and Like us!

Cold Weather Discussion

Next Monday Nov. 19th, we’re going to have a google+ discussion (that means digital cameras) on getting ready for cold weather. It will be scheduled for 2:00 Central, 3:00 Eastern, 1:00 Mountain, and 12:00 Pacific. It will be Linda, Myself, and a few other people. If you have any interest in participating, or any burning questions, please drop me a line at gillm003@umn.edu. We’d like to get three or four people from cold climates on with us!

Yes, this will be on YouTube a few hours after the discussion occurs.

Vacation in Colorado and Washington

Wow, election week. Maybe your candidate(s) won, maybe not. To be perfectly honest I’m not really sure that we know whether we’ve won or not until they actually take office and start doing things. Along with the candidates, you probably also had the opportunity to vote for other things, like whether your state constitution should include an amendment saying that a marriage should be between a man and a woman or whether IDs should be required for voters to vote (those were the two on the Minnesota ballots).

For us horticulture types there was one vote that really made us happy. In Colorado and Washington they voted to legalize marijuana for recreational use. OK, I should come clean – I’ve never smoked marijuana. Been around it, sure, but I have never actually partaken. At this point in my life I don’t think I’d bother with it regardless of whether it was legal or not. So why am I, and other horticulturists, so excited about it? If things work out this is a new crop to work on, and new crops are fun. Breeding, growing techniques, maximizing productivity, etc. Shoot, maybe there will even be new grants for this stuff to fund the work. And imagine the fun that we extension types will have writing about it! I can’t wait.

Webinar update – yes, YOU can attend!

A few days ago I posted about a webinar I’m doing on using academic databases for gardening myth-busting. At the time I wasn’t sure what the rules were for viewing the webinar, but happily I’ve found out we can have outside viewers! So here’s the information about when and how to log on to Adobe Connect (keep in mind this is Pacific Standard Time here).

Speaker: Linda Chalker-Scott

Date: Wednesday, November 7

Time: 10:30-11:30 a.m.

Address: http://breeze.wsu.edu/ext_skills/

We have 99 slots for people, so there should be plenty of room. And if you can’t make it, no worries. The presentation will be archived so you can watch it over and over and over…

I’ve gotten some great ideas from you – thanks! Hope to see some of you there.