The Garden Professors™ – Page 59 – Advancing the science of gardening and other stuff since 2009

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!

Research that gardeners should appreciate!

Today I received my November 2012 issue of Arboriculture and Urban Forestry. This is one of the few peer-reviewed journals that generally has information of immediate value to gardeners and landscape professionals as well as academics. This issue contains an article entitled “Evaluation of biostimulants to control Guignardia leaf blotch (Guignardia aesculi) of horsechestnut and black spot (Diplocarpon rosae) of roses.” (And before you ask, no, I can’t attach the article or link to it. You’ll need to read it in the journal itself or wait for a year when the organization makes it available to everyone.)

Anyway, this study looked at eight different self-identified biostimulants, including Superthirve (which every gardener must have heard of by now). In addition to Superthrive, the other products tested were Maxicrop Original, Resistim, Bioplex, Fulcrum CRV, Redicrop, Crop Set, and Systhane. Purported active ingredients within this group include seaweed extract, molasses, vitamin B, and Lactobacillus fermentation product.

And the $64,000 question – did they work? Here’s the authors’ summary: “Irrespective of pathogen or concentration applied, none of the biostimulants used in this investigation provided a significant degree of Guignardia leaf blotch or black spot control compared to water-treated controls.” In other words, you can expect the same results by spraying your black spot-infested roses with water compared to any of these biostimulant products.

The authors end their article with a caveat sure to warm the cockles of every Garden Professor’s heart: “Results of this study indicate that where independent scientific data are not available to support the pathogen control claims of the manufacturer, then using an unevaluated biostimulant for this purpose is not recommended.”

(I’m glad this article is finally out. I was one of the peer reviewers for it, and I’ve been wanting to share the results on the blog ever since I read it.)

What would YOU do?

Once in a while we end up flicking around the dial on Friday evenings and land on a show called “What would you do?” It’s a hidden camera-type set up where viewers get to see the reaction of everyday folks faced with awkward or contentious situations like an overbearing customer berating a waitress over a minor mistake in their bill. The scenarios are played out by actors but the people responding are not. Personally I find the premise of the show slightly annoying because it smacks of entrapment but it seems to lure in the rest of my family.

Today we’ll do our own version of “What would you do?” In this case, however, the situation is real. Here’s the deal. Michigan State University has begun work to complete the Facility for Rare Isotope Beams or FRIB across the street from the Horticulture building. This $615 million dollar project will enable physicists to study rare nucleotides, the kind of elements that only exist for fractions of seconds. It’s definitely big science stuff and can lead to all kinds of exciting discoveries. In looking at some of the plans for the FRIB, however, some of my colleagues discovered that the FRIB completion will require removal of several large mature oak trees that close to 100 years old. The initial effort to save the oaks focused on re-locating the portion of the FRIB that conflicted: No dice. The next option was to move the oaks. Due to various factors, only one tree, a bur oak about 3 feet in diameter, can be moved. The price tag: approx. $150,000. The move date is currently set for Dec. 10. Now another option has surfaced: remove the mature oak and use the $150k to plant new trees around campus. Our landscape services typically plants 2” caliper shade trees and 6’-7’ conifers so we’re probably talking 400-500 trees. I am part of a group that will try to hash things out on Wednesday.

So, what would YOU do? Save one large mature tree or plant 400+ new?

Here’s a look at the oaks through the years…

Today. Oaks trees are located in median in center of the image.

1980 during construction of the Wharton Center for Performing Arts

1965

1955

A Note To Horse Owners

Every once in awhile I get to work with really, really cool people who do really, really cool work. This is one of those times. About a year ago I received a message from Dr. Stephanie Valberg, a Professor over at the University of Minnesota’s Equine Center. It seems that she was interested in looking at a deadly disease called Seasonal Pasture Myopathy which she thought might have something to do with horses ingesting maple leaves. Specifically, at the time she contacted me, she thought that this disease might be associated with horses ingesting tar spot, a common disease that maples get. Seasonal Pasture Myopathy is a particularly nasty disease because it is fatal in over 90% of cases, and the death is far from painless.

After doing site visits to many farms where this disease was found, she discovered something very important: Every farm had box elders in a location where horses could feed on the seed when they got hungry. And for most of the farms, horses were also dealing with scant pickings in terms of food. They usually had sparse pastures and not much supplemental hay. So, in these conditions, the horses might find box elder seed attractive, or at least palatable.

After a literature search, Dr. Valberg discovered an old article showing that box elder seeds could very well contain a toxin, hypoglycin A, which might cause this disease if they were eaten. After testing the seeds for the presence of this toxin (Done by a friend of mine, Adrian Hegeman, located here in the University of Minnesota’s Department of Horticultural Science) it was established that, Yep, box elder seeds have this toxin, and if your horse eats them, it might be in trouble. You can find out more here.

Right now more work is going on to see if this toxin is more or less present in box elder trees that are under stress, if it is present in other parts of the tree besides the seeds, and at what time of year the toxin might be most present in the seeds. It also looks as though some other maples may have this toxin in their seeds, most notably sycamore maple.

All in all, having the opportunity to watch this work unfold has been one of the highlights of my career. It was like watching an episode of House unfold in real life. And the great part is that this work has the potential to save the lives of dozens, if not hundreds or thousands, of animals. So if you have horses, and box elder or sycamore maples in your pasture, be careful!

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.

Important, must-read announcement regarding pesticide use

There’s a new report out from the Weed Science Society of America (WSSA) which blasts a common piece of gardening advice: use least toxic pesticides only as a last resort. Popular as it may be, this advice is not scientifically grounded and can actually cause more harm than good. The WSSA is joined in this announcement by the American Phytopathological Society (APS) and the Plant-Insect Ecosystems Section of the Entomological Society of
America (P-IE ESA).

This is a must-read for anyone who is a responsible educator regarding pesticide use, which includes Master Gardeners and other horticulture paraprofessionals. You’ll want to use the webpage link above to read the entire announcement, but here’s a paragraph to get you thinking:

“There is no benefit or scientific basis to simplistic messages like “use least toxic pesticides as a last resort” for the large number of pesticide users who apply pesticides according to the label and practice good stewardship. Nor are these messages beneficial for those who neither seek training nor adequately read the label believing instead that it is safe, practical, and effective to simply choose a product considered a “least toxic pesticide” and apply it only as a “last resort.” These messages hinder pesticide safety and stewardship education and practices that are in the best interest of the pesticide user, our food supply, public health and ecosystem preservation.”

Finding agreeable things not sought for

As a graduate student at the University of Georgia many years ago I took a course in research methods. One of the discussions that stuck in my mind all these years centered on the word ‘Serendipity’. The classic definition of the word is “the faculty or phenomenon of finding valuable or agreeable things not sought for.” As scientists we rely heavily on the scientific method as a systematic method of inquiry to make new discoveries. But we also need to need to keep our eyes and minds open to serendipitous discoveries along the way as well.

So what got me thinking about serendipity? A few weeks back I visited a Christmas tree grower in northern Michigan with Jill O’Donnell our state-wide Christmas tree educator. The grower called us in because he had some questions about some unusual trees in one of his Fraser fir plantations. And, not only were the trees unusual, they were gorgeous. The only question was; what were they? The plantation originated from seed the grower had collected himself from some older Fraser fir trees he kept as a seed orchard. He sent the seed to a large forest nursery in the Northwest, which grew the seedlings and sent them back to him. The grower wondered if seed of another species could have been introduced in the process. Possible, I told him, but not very likely. Nurseries that are serious about contract growing are meticulous in keeping seed lots separate – few things are worse in that business than sending the wrong seedlings. Plus, I’ve worked with many species of fir and this was one I didn’t recognize. The trees had many characteristics of Fraser fir but also had attributes of concolor fir; long bluish needles and a slight hint of citrus scent when the needles were crushed. Many fir species can hybridize and all I could think was these trees had to be hybrids. “Are there any mature concolor firs near the seed orchard?” I asked. The grower brightened, “Actually there’s a group of older concolors about a half mile up the hill from the Fraser fir orchard.” We jumped in his pick-up and visited the concolor firs. Many of the trees had cone stalks indicating they were reproductively mature and could produce pollen. Conifer pollen can travel for miles so it’s reasonable to expect that some of the concolor pollen could reach the Fraser firs, which were downhill and downwind based on the prevailing winds in the area.

Excellent tree form of the mysterious hybrids

So what’s next? There are several reasons to follow up on this serendipitous discovery and try to make some additional crosses. First, as evidenced by the photos, the trees look fantastic. Second, Fraser fir and concolor fir are each great trees but they also have some liabilities. A downside of concolor is that they break bud early and often suffer late frost damage – Fraser’s break bud late. Fraser fir need acidic, well drained soils – concolor fir can grower on a broader range of sites. It’s possible that the hybrids will have intermediate characteristics that would make them ‘the best of both worlds’.

Foliage close up

The only thing left is to decide what to call the hybrids. Nurseries like to combine common names. So, Craser fir? Froncolor?

A different kind of storm chaser

As an Extensional Specialist working on urban and community forestry issues, I am frequently asked to respond to questions about tree damage after storms. One standard bit of advice I give is to be wary of ‘door knockers’ or ‘storm chasers’; individuals that descend like locusts upon storm-ravaged areas with pick-up trucks and chainsaws offering to clean up storm damage. Sometimes these are just honest folks trying make a buck but there are also less scrupulous folks in the mix that are clearly exploiting the misfortune of others. In either event, they usually lack the training, not to mention insurance, to tackle the dangerous chore of removing downed trees around homes, cars, and people.

In trolling the internet the other day for photos for Monday’s post, I ran across a different kind of storm chaser. It seems the internet has gone viral with photos of Brazilian glamour model, Nana Gouvea, who was photographed by her boyfriend in various settings among the devastation of Superstorm Sandy. The photos were posted on (and subsequently removed from) from FaceBook. Needless to say, many people were offended and have taken the model and her boyfriend to task for the photos and a FaceBook site has popped up with Photoshopped images of the comely model amidst other disasters from the killing of Bambi’s mother to Noah’s flood.

Personally, I think the public needs to cut Ms. Gouvea some slack. This intrepid beauty has captured a teachable moment and performed a great public service for extension personnel everywhere. I can see future hazard tree assessments talks and bulletins enlivened with her images. Well, here, let me show some examples.

Note the upturned in roots in the upper left. Poor root anchorage is a common cause of tree failures during storms.

Trees breaking at ground-line (far left) during high winds is often the result of girdling roots.

Trees snapping at mid-stem is often the result of a subtle defect. Note the evidence of frost cracking below this breakpoint.

Archived webinar available

We had a decent turnout on the webinar yesterday – saw a few names from our blog readers there. I hope everyone was able to see and hear the presentation and didn’t have any technical difficulties? If you did, please let me know so we can fix them for next time. For those of you who weren’t able to attend, it’s been archived for viewing at your leisure.

I used suggestions that readers suggested on the blog to demonstrate how to search academic databases for science-based information on products and practices related to gardening. So if you’re curious to know whether wireworms can be controlled naturally using bait traps, or whether hydrogen peroxide as a soil drench will prevent damping off off seedlings, or whether mowing leaves into the lawn is a good practice…you’ll have to watch!

Possum 1, Garden Professor 0

It was a dark and stormy Wednesday night.

Joel opened the porch door and whispered “you’ve got to come see this.” He’d taken the dogs out for their 9:00 p.m. constitutional, and there was apparently some excitement under the old apple tree.

“There’s a possum, and I think she’s playing dead.”

I grabbed the flashlight and hustled out. Got around the corner to the tree, and sure enough, there was a rather large blob of silver and white mammal.

But as I got closer, my heart sank.

She was curled up, head askew, front leg sticking out at an odd angle. Lips (?) pulled back , teeth and gums bared in a terrible grimace, tongue hanging out the side. I shined the flashlight right into her eyes. No movement, no pupil dilation. Being from a farm in Georgia, I claim the most possum and raccoon experience. Thus, my verdict. Deader than a doornail. Which made me sad.

“Aargh. Thanks. Now I’m upset. Guess she got hit by a car and made it this far before expiring. Could you put her out at the end of the garden? The soil’s pretty soft there.”

Joel apologized and went to get the shovel. I scuffed back inside to finish the dishes, feeling awful for the little critter. Thanks to our impenetrable hen stockade, we live in pretty good harmony with our country cousins, and hate to see harm come to them.

Ten minutes later, Joel was back at the door, shovel in hand.

“Um, I think it was faking.”

“No way. That possum was graveyard dead.”

“Well…it seemed to be o.k. enough to be sitting up and eating an apple.”

We hiked back out to the tree – no possum to be found. My wildlife cred was blown.

“Looks like she was playing possum” I offered, helpfully.

Joel muttered “But I just dug a three-foot-deep hole.”