woody – Page 5 – The Garden Professors™

Vote early and often!

In my last post I announced that we would be conducting the first landscape transplant experiment designed by social media. We have about 100 ‘Bloodgood’ plane trees in 25 gallon containers that are leftover from a recent nursery trial. The trees will be planted at our Hort station and receive minimal care after planting beyond an initial watering and a kiss for luck. I asked for some suggestions for potential treatments and got some good suggestions. Unfortunately, one thing I forgot to point out is that I have essentially no budget for this project. So trying to determine whether or not roots are mycorrhizal, or bringing in B&B trees for comparison, are beyond our capabilities at this juncture.

We did have some interest in determining the effects of manipulating rootballs for container-grown trees. These trees have been in pots for 2 years and I absolutely guarantee they are pot bound. Definitely a good opportunity to look at shaving or teasing rootballs.

There are a couple of other items that I am curious about.

One is crown reduction thinning. In forest nurseries trees are often top-pruned to reduce shoot-root ratio and increase transplant success. Obviously we would’t top landscape sized trees, but can selective pruning to reduce the ratio of crown area to root area reduce water stress and increase survival?

Along these lines, there is a lot of marketing of plant growth retardants to reduce transplanting stress. The most common is probably paclabutrazole – sold under various trade names including Cambistat http://www.treecaredirect.com/Cambistat-Tree-Growth-Regulator-p/3101.htm Does it work?

I’ve also been curious about hydrogels. I’ve long been a skeptic but have had several arborists tell me they’ve used them successfully – of course they didn’t leave an untreated control.

Then, of course, there’s Bioplex. http://www.bio-plex.com/pdfs/Bio-Plex2009Catalogue.pdf It might be easier to list what isn’t in Bioplex than what it contains. I suspect whatever effect it has is largely related to small amount of nutrients it contains.

Lastly, I still adhere to the notion that fertilizing trees at planting is not necessarily the source of all evil in the world and may even be a good thing. Here I get a chance to provide myself wrong and apply a dose of Osmocote in the planting hole.

OK that’s the background – time to vote. The link below should take you to a Survey Monkey survey. You can vote for more than one item, but please vote for no more than three.

http://www.surveymonkey.com/s/W3YGGSD

High-end WOW (Why oh why)

A few weeks ago I was lucky enough to speak to the Portland Garden Club and see some absolutely gorgeous private gardens. But alas…even in the midst of such botanical riches I still managed to find something to make me shudder.

Now I have nothing against garden remodels – or boxwood hedges (though I generally find them unimaginative). But here’s a good example of shrub salvaging gone horribly wrong:

Deadwood boxwood

And again

It will take a long time for these boxwoods to fill in. If you’re going to spend the kind of money that’s going into this remodel, why get chintzy with the hedge plants?

Maybe green spray paint is in order?

An unusual company

This week I’m in Charlotte, NC as a guest of Bartlett Tree Experts. In addition to providing tree services, this company also maintains the Bartlett Tree Research Laboratories and Arboretum. The latter includes over 300 acres of tree collections and ongoing research trials. Here’s a sampling of the tree research we had a chance to observe:

Demonstration espalier pruning…

…and pleaching

Comparison of root barrier materials. This area was covered with a sidewalk for a number of years and then exposed to observe tree rooting patterns. The purpose of the research was to find which barriers were most likely to prevent sidewalk lifting and cracking.

A control – no barrier, lots of roots!

Black plastic – lack of rigidity allows roots to grow over (and through) the plastic, then under the sidewalk.

18″ rigid root barrier. One of the more effective means of keeping roots out.

Removing circling roots before planting

A tree whose roots had been corrected before planting. I think this had been planted in 2007, then lifted a few weeks ago.

A tree without root correction. It didn’t grow any better than the corrected tree, and those circling roots are well on their way to becoming girdling roots.

This company employs a number of PhDs whose research is routinely published in arboricultural and horticultural journals. It was fun to finally meet these researchers whose work I’ve been following for years.

Wouldn’t it be great if more companies put this much effort towards research?

Pop quiz time!

It’s the start of new semester. Best way to get student’s attention is with a pop quiz right off the bat! So in that vein, we’ll cross things up and give a quiz on Monday instead Friday. Relax; to make things a little easier we’ll make this one a matching exercise.

Here goes. At our recent Christmas tree conference in Austria, a colleague of mine at Oregon State University, Chal Landgren, presented the results of a study to look at the effectiveness of foliar fertilization on Nordmann fir. Trees were grown in 15 gallon containers and assigned to one of four groups:

1) control: no fertilizer

2) soil applied controlled release fertilizer

3) foliar nitrogen fertilizer

4) soil applied fertilizer + foliar feed

Since Chal has yet to publish this I need to be a little careful with details but all fertilizers were commercially available products labeled and marketed for this purpose and were applied at manufacturers’ suggested rates and intervals.

At the end of the growing season, the trees were sampled for needle nitrogen content. As a point of reference a needle nitrogen content of 1.5 – 1.6 % is usually deemed adequate for this species.

For your quiz: match the treatments listed above to the nitrogen concentrations below:

a) 1.14%

b) 1.91%

c) 0.98%

d) 1.70%

Answer and discussion tomorrow…

Podcast #7 – Better Red Than Dead

This week’s podcast is dedicated to anthocyanins – those pigments that give plants red, blue, and purple colors. Anthocyanins are also powerful antioxidants, important visual signals for pollinators, and often deadly to insect pests. The myth of the week explains why red leaves aren’t usually a sign of phosphorus deficiency, but instead an indicator that anthocyanins can help plants survive many environmental stresses.

My interview this week is with Cass Turnbull, founder of PlantAmnesty, a Seattle organization dedicated to “ending the senseless torture and mutilation of trees and shrubs.” My son Jack took the interview photos, and Cass supplied the others from the PlantAmnesty photo archive. You’ll love the way she combines her educational message with humor!

Cass on her “throne”

One of the nonbotanical garden residents

A selection of PlantAmnesty humor

Please let me know what you think of the podcast; you can email me directly or post a comment on the blog. Suggestions for future podcasts are most welcome!

Spin Cycle

The issue of potential damage to conifers by the turf herbicide Imprelis continues to get a lot of air play in this neck of the woods. One of the interesting things about watching an emerging story such as this is watching some of the sideshows that go on around it and how people spin the issue to match their needs and agenda.

Example 1:

Heritage Lawn Care Company put out flyers in neighborhoods in southeast Michigan with affected trees to promote their service. The flyer incldued the heading “ALERT:DYING PINE AND SPURCE [sic] TREES” The flyer claimed that issues related to Imprelis damage to trees are “99.9% applicator and mixing errors”. Surprisingly, there was no mention of where they got the data for this assertion. But fortunately Heritage stands ready to save the day by using “only organic based fertilizers giving the same or better results”. Again, no mention of how organic fertilizer controls tough weeds like ground ivy and wild violet. Thankfully, “If you prepaid (your lawn care provider) for 2011, and want to switch companies, Hertitage is willing to extend you credit until your current company refunds your money.” Call it a hunch, but I don’t think the folks at Heritage will be receiving an invitation to the local landscaper’s group picnic this year…

Example 2:

Mother Earth News trumpeted the news on Imprelis with the headline “Imprelis: Another Deadly Herbicide, This Time From DuPont” http://www.motherearthnews.com/grow-it/imprelis-killer-compost-zb0z11zrog.aspx First of all, isn’t ‘Deadly Herbicide’ redundant? Every ‘icide’ is designed to kill something so I think they’re supposed to be deadly, at least on their target. While the unintended damage to spruces and pines is certainly unsettling, especially for a newly released product, this group of herbicides has low toxicity to mammals and in many regards is comparatively safe. I don’t consider myself a nozzlehead but I’m sure most GP readers recognize I have little aversion to judicious use of chemicals around Daisy Hill farm. So I was a little taken aback to find my “Fasten your seatbelt folks, this could be a bumpy ride” (GP Blog 6/27/11) quoted in Mother Earth news. My reference was to applicators having to deal with customer complaints and potential litigation – but that’s the nature of putting things into the blogosphere…

Example 3:

On July 14 I received an e-mail advertisement from Growth Products, Inc. breathlessly announcing “An Essential Cure For Trees Damaged By Imprelis Or Sahara Herbicides.” Pretty impressive stuff: We’ve only known about the issue for three weeks and these guys have already found the cure. I had to read on. The cure consists of an “Essential Cocktail” of three Growth Products liquids including Essential Plus (a rich concentration of organic ingredients including humic acid), Micrel Total (“Eight chelated minors to help the tree through stress”) and Companion (a biological fungicide). Alas, once again eye of newt and wing of bat were apparently out of stock. But, “The magic mix can be used as a soil drench and/or a soil injection.” The e-mail also included a link to an article I wrote for our extension news that included a photo of some maple trees that had largely recovered from herbicide injury by Sahara in 2009. I also documented the case here on the GP blog I wasn’t aware, but apparently a landscaper treated the trees with some of these concoctions. No word in the e-mail from Growth Products on how the untreated control trees did.

Imprelis update

I’ve been continuing to track some of the reports of injury to conifers associated with the new herbicide, Imprelis. Interest in the problem is likely to escalate given a front page article in the Sunday’s Detroit FreePress. http://www.freep.com/article/20110710/NEWS06/107100467/New-lawn-chemical-chief-suspect-mysterious-deaths-trees

I visited about ten sites last week with an applicator that had used Imprelis this spring. The landscaper was a certified applicator with about 15 years of experience with herbicides, insecticides and fungicides, who was knowledgeable about his chemicals and plants. We saw bout 50 trees, mostly pines and spruces with varying levels of injury. The typical symptoms were brown or off-color needles, and stunted or twisted shoots. Damage was mostly limited to the current flush of growth, resulting in a distinctive pattern of growth. In many cases, there was evidence of spiral movement up the trunk of the tree. The most rapid growing points (usually terminal leaders) were most severely affected. Based on my experience with other forms of herbicide injury and other types of environmental damage, I suspect all but the most severely injured trees would recover is given enough time and some corrective pruning. The problem, of course, is that most homeowners don’t want to wait around while the tree in their yard tries to rally.

Some photographic ‘highlights’

The $64 question now becomes, “What happened?” In order to receive registration from the US EPA, each new herbicide has to go through extensive testing. According to DuPont, over 400 tests were conducted with Imprelis. Despite some claims elsewhere on the internet, this testing included independent university trials on spruces and pines at up to 4x the labeled rate. The key to unlocking the mystery of Imprelis injury will probably lie in understanding how conditions in actual application conditions differed from the testing.

Imprelis damage to landscape conifers

Herbicide issues seem to be dominating my life these days. Over the past several weeks reports have surfaced around the Midwest of landscape conifers – primarily spruces and pines – that have developed rapid and severe die-back. While there are a host of insect pests and pathogens that can cause die-back in conifers, the recent cases are noteworthy in the speed with which trees expressed symptoms.

Photos: Andy and Carol Duvall

In many cases that have been reported the common thread appears to be the use of Imprelis, a turf herbicide developed and marketed by Dupont. Imprelis (active ingredient: aminocyclopyrachlor) is a synthetic auxin designed to control broadleaved weeds in turf. Ostensibly, one of the advantages of Imprelis is that has root activity in addition to foliar activity. It appears, however, that it may have too much root activity and the internet is abuzz with photos and posts of Imprelis-damaged conifers. http://bestlawn.info/northern/imprelis-and-dupont-trouble-t4608.html

http://www.buckandsons.com/blog/tag/dupont-herbicide-imprelis/

So what’s going on? Well there are lots of blurbs coming out and lots of things being reported second and third-hand. I suspect a few things we ‘know’ about Imprelis right now will turn out not to be the case in a few months. Dupont has tried to shift blame to the applicators, suggesting that their rates may have been off, they applied when there was potential for drift, or that the material was mixed with other herbicides. http://www.ksuturf.org/blog/wp-content/uploads/2011/06/DuPont-Letter-to-Turf-Professionals-061511.jpg

Given that reports of damage showing similar symptoms have come from Kansas, Iowa, Indiana, Michigan, and Ohio it seems unlikely that everyone is mis-applying the product. I suspect one of a couple things may be going on. Dupont may have underestimated the lateral extent of tree roots, especially for conifers that often have shallow, extensive root systems. It’s also possible that Norway spruce and white pine are more sensitive to this product than whatever Dupont tested it on.

In the meantime stay tuned. In case people haven’t figured it out for themselves, Dupont now recommends that applicators not use Imprelis near spruces or pines (see letter linked above). Landscapers or lawn service operators that have applied Imprelis should keep in touch with their state Department of Agriculture and their professional turf and landscape association. Might be good to fasten your seatbelts, this could be a bumpy ride…

WOW again (Why oh Why?)

I’m going along with the “dead tree” theme of the week, but doing a little prognosticating at the same time. Bert and Holly showed you tree demise on site; I’m going to show you tree demise in the making. We can call this “dead plant walking.”

I’ve done a few WOW postings in the past, often with a focus at what you might find at a nursery or big box store. Here’s a recent find at an unnamed BBS, in the “topiary” section:

Unless you intend to have a giant stake as part of your topiary statement, this tree (actually a juniper) will morph into a prostrate form before your very eyes. Fortunately, it probably won’t live long once transplanted since it’s so overdue for potting up that the pot has split:

You can just imagine the nest of woody roots fusing into a functionless mass, can’t you?

Run, don’t walk, away from nursery plants like this. You’ll be glad you did.

Getting to the root of the problem

After getting off to a cool and soggy start, summer has come with a vengeance to Michigan, with heat indices expected to push 100 degrees by Wednesday. Along with warmer temperatures, summer also means our research season is getting into full swing as well. One of our biggest efforts these days involves our project to look at pre-plant storage and handling on shade tree liners.

As many GP blog readers are aware, emerald ash borer (EAB) has dominated the conversation regarding shade trees in the Midwest for the past 6-8 years. Ashes made up 20 to 30% of the shade tree cover in many urban and community forests, so their loss has been devastating. A major thrust of our extension programming during this time is to promote a wide range of ash alternative to increase species diversity. One of the challenges we find in making this pitch is that many of the species we recommend (oaks, hackberry, baldcypress) are trees that nurseries often find difficult to grow from standard bare-root liners.

My graduate student, Dana Ellison, is in the second year of a project to look at some of the practices that growers use on the difficult to transplant species and some of the underlying causes of poor transplanting. Dana is looking at a variety of attributes including plant water relations and carbohydrate status, but the order of business these days is roots. Specifically we’re evaluating root growth potential of oak, baldcypress, and hackberry. We’ve also included white ash, which transplant easily, as a positive control.

Graduate research assistants Dana Ellison (right) and Brent Crain (left) and undergraduate assistant Arriana Wilcox (center) pot up shade trees for root growth potential testing.

Root growth potential (RGP) is a common parameter in evaluating quality of reforestation seedlings but is measured less often on larger liner material. The logic is pretty straightforward; a plant’s ability to initiate root growth after plating and re-establish root-soil contact is one of the biggest determinants of its ability to survive and grow. A variety of systems have been used to evaluate RGP for seedlings – most involve growing seedlings for a set time (3 weeks is standard) in an aeroponic system and then counting or measuring new root growth.

Growing the trees in pea gravel makes it easy to get a look at new roots.

For Dana’s shade tree liners (5’-6’ whips) we’ve adapted a system based on the Missouri gravel bed system (which I first got to see in person at Jeff’s research nursery in Minnesota – thanks Jeff!). Dana and her helpers pot the trees up in pea gravel in 25-gallon containers. The trees are grown on for three weeks in a greenhouse while the roots are kept moist with spray stakes operated by a mist system timer. After three weeks, we dump out the gravel, wash the root systems, and carefully count the number of new, white root tips.

Dana washing roots.

So what have we learned? Well, the work is still on-going but some trends have emerged. Baldcypress may experience some transplant issues but they don’t appear to be related to producing roots. We had several baldcypress trees that produced 400 or more new roots during the RGP test – and, yes, we counted them all! Red oak and northern pin oak, on the other hand, are very slow to put out new roots. For hackberry trees, our other measurements suggest their transplanting issues may be related to their inability to re-hydrate after lifting, storage and transport. These insights should help us provide some guidelines to growers to help them produce a wide pallet of trees for the landscape market and increase species diversity in the wake of EAB.

Counting roots. Almost as much fun as it sounds…

The defending champion baldcypress: 614 new roots.