What About the Trees – Page 5 – The Garden Professors™

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…

Right Plant, Wrong Place?

It’s (apparently) Dead Tree week here on the GP!

[To my GP colleagues…we should make “Right Plant, Wrong Place” one of our categories, sort of like “Knock it Off.” Or maybe just “Dead Plants in Action.”]

Exhibit A:

Some unhappy little Magnolias. Drip irrigation was running, which leads me to believe salt spray is the culprit.

I was pedaling my sweet Electra beach cruiser down the sidewalk on Cape San Blas, Florida (or Cape San Blarrrgh, if you caught my post last week) and happened upon this tragedy. In the background is natural coastal sand pine scrub including saw palmetto and myrtle oak. Growing on nothing but sand and a bit of decaying organic matter, 300 yards from the ocean, these are tough plants. Pretty darn salt tolerant. Cabbage palms, also very salt tolerant, marched along the sidewalk. Southern magnolias had been planted in between, and they weren’t faring as well.

Just like “deer resistant,” “salt tolerant” is a rather vaguely-defined grouping of plants. You can find list after list on the interwebs and in the back of nursery catalogs and reference books. The source of the information is rarely confirmed, and if so, it’s the same Extension publication that has been cut and pasted to death. Degrees of salt tolerance are further described as “high,” “moderate” and sometimes “low” without any quantitative parameters (a range of soil electrical conductivity perhaps?). There are tremendous scientific resources (including funding) devoted to breeding for salt tolerance of food crops like rice, barley, and soybeans. Ornamental plants are pretty unimportant in the grand scheme of things (like the global food supply) thus the mere smattering of practically unfunded research out there, leaving us with only anecdotal evidence. Though some lists have M. grandiflora listed a “moderately” salt tolerant, I vote to move it to “low.”

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.

Trees: Dead or Alive

In light of the comments on Dr. Jeff’s latest post (When Trees Don’t Know They’re Dead), especially those by Shawn, Ed, and Dr. Linda, I absolutely have to post this.

To the best of my knowledge, the number of stand-up comedian bits related to tree health can be counted on one finger. Here it is, transcribed, as close as I can without having Linda ban me from the blog/WSU server.

Ron White is a big, bawdy, laid-back Texan, permanently armed with a cigar, glass of scotch, and high-beam smile. I think he got thrown off the Blue Collar Comedy tour for not being red-necky enough. However, not recommended for the easily or moderately offendable. Anyhoo, here goes, and it suffers without the drawl…

****
From Ron White’s You Can’t Fix Stupid recording
(verbatim, mostly):

I was having a fight with the landscape guy because, like, half the plants died…you know it cost tons of money and half the plants died. And the guy is fighting with me over whether or not a tree is alive or dead. Can you believe that bleep? We walk over to two trees, there’s not one leaf on either one of them except [you look toward the] timber [where the] the forest is a-blooooom.

I said “those two trees are dead right there.”

He goes over to one of the trees and scratches the trunk with his thumb and comes back and says this, and I quote: “The core of this tree… is still alive”. [Long pause]

I said “Let me tell you what I’m looking for in a bleeping tree.”

[lotsa laffs]

I’m looking for tree that you can tell is alive even if you don’t know bleep about trees.

I don’t want to spend the next two years every time somebody comes over to our house “… oh no, those trees are fine right there – go scratch the trunk with your thumbnail. You will find a vibrant core. Just beneath the bark.”

******

Looking for the lowdown on tree rings

Often we use our blog space as a soapbox from which to pontificate, but today I’m looking for some input from our loyal readers. Last week I received a note from an editor looking for some words about tree rings. We’re talking about landscape tree rings for planting annuals or perennials, not dendrochronology.

The editor was interested in specifics on tree rings for large existing trees such as what type of materials to use, what types of flowers or plants worked best, which trees can or can’t have tree rings, etc. My reply was short, maybe even a little curt, “I don’t have any experience with tree rings but our general recommendation is to avoid grade changes around trees whenever possible. After I sent the reply I started thinking, is there any real harm to tree rings? I’ve seen some that looked pretty nice (seen many that look like crap, too). For most trees the amount of surface area covered is small compared to total surface root area. If care is taken not to bury the root collar and trunk, would the tree notice covering a little bit of mostly structural roots? Would appreciate thoughts (pro and con) from those with direct experience.

Keep Calm and Carry On: Part II

Recently I posted that many of the “rules” that gardeners cling to so tightly regarding tree planting (i.e., dig the planting hole 3 times the width of the root ball, always amend the backfill with organic matter) are probably better considered ‘suggestions’ than rules. While these practices won’t hurt, there are much better ways to spend time and effort to ensure long-term survival when planting a tree. Here are the top four:

Irrigate. No matter how much time and effort goes into the ‘perfect’ planting hole; for most parts of the country, trees that are not irrigated after planting are doomed. Linda advocates watering in several small sips during the week; I still stick to the old school notion of one long soak per week. In the final analysis, logistics will probably dictate which approach you use. Either way, the key is to provide trees with water during the establishment year and even into the second year after planting, if possible.

Mulch. Organic matter placed properly on top of the planting hole will do more good than organic matter placed in the planting hole. Study after study demonstrates that mulch conserves soil moisture by reducing evaporation from the soil surface, controls weeds, and moderates soil temperature. Oh, and that business about wood-based mulches ‘tying up’ or ‘stealing’ nutrients from landscape plants? Maybe for bedding plants, but not for trees and shrubs. Our research and other studies indicate that, for the most part, the type of organic mulch makes little difference compared to not mulching at all. Hence, my motto “Mulch: Just do it.”

Proper planting depth. Width of the planting hole may not matter, but planting trees too deep is a recipe for disaster. Burying roots too deep reduces oxygen levels around the roots and starts a series of unfortunate events for the tree. Find the root collar flare and keep it visible.

Bad move. The contractor was going to install drain tile but decided not to at the last minute to save money. Ouch.

Right tree, right place. In my experience, the number one reason newly-planted trees fail in the first year is lack of watering and aftercare. After year one, improper tree selection takes the top spot. Here in the Upper Midwest, poor drainage and heavy soils take their toll year after year. Lack of water can usually be addressed, but once a tree is planted in a spot that is too wet for that species, it’s usually a long, slow, and agonizing decline. And it’s amazing how often people will ignore obvious red flags in selecting trees. Our Dept. of Transportation recently planted 25 eight-foot B&B eastern white pine, which are notoriously salt sensitive, about 30’ from I-96 at a rest area between Lansing and Detroit. Predictably, after one winter’s exposure to deicing salt spray all the trees were dead or wishing they were dead. Right tree, right place. This ain’t rocket science, folks.

When trees attack!

We typically think of trees as the ‘good guys’; they shade our homes and yards, they take up carbon dioxide and pollutants from the air, they give us oxygen. What’s not to like? Well, like a lot of good guys, trees can also have a dark side. One of the more sinister habits some trees have is getting into sewer lines. Some studies estimate that trees are responsible for up to half of sewer line repair costs. The prospect of trees getting into residential sewer lines is troublesome, of course, because it’s an invisible problem; we usually don’t know there’s an issue until there’s an issue. Once tree roots get into sewers, they are often expensive and messy to deal with. And I don’t mean just messy in the sense of having to call in a backhoe to dig up your yard. Deciding who is responsible for the cost of cleaning up after a tree figures out its hit the mother lode can be a mess as well. What if your neighbor’s sycamore finds its way into your pipes? Or what if the culprit is the silver maple that you didn’t want but the city planted in the tree lawn anyway? In some cases there are city ordinances that cover these situations. For example, some cities will cover damage from city-owned trees provided they determine the city-owned tree caused the damage and the damage wasn’t due to a pre-exiting problem with the pipes. Therein lies the rub. As long as sewer pipes are intact and functional, tree roots have a hard time penetrating. The problems usually arise when pipes crack or joints fail. Once roots find an opening, it’s Katie bar the door. This is why tree-sewer problems are most common in older systems with clay or concrete pipes that can crack over time. Of course, the type of tree and location play a role as well. Other factors being equal, fast-growing bottomland species are the most frequent offenders. Danish researchers found that willow, birch, and poplar trees were responsible the largest number of root intrusions into sewer lines. In many parts of the US, sycamore, sweetgum, and tulip-poplar can be added to the list.

Tree roots and sewer lines: a bad combination
So what’s a homeowner to do to get some sleep and not worry about tree roots planning a silent assault on the drain-lines? Keeping fast-growing trees away from lines is a start. But tree roots can grow a long ways and are pretty relentless; if there is a crack or a weak spot in the pipes, they will find it. Keeping the system maintained and preventing entry is the key. If the system has cracks, “Root-stopper” or “root-killer” products are available. These are copper-based materials similar to ‘spin-out’ used on tree containers to prevent circling roots. These will kill feeder roots that have entered into pipes, but roots are persistent and they’ll be back. Plumbers have special tools that they can snake through the system that can cut through roots and clear blocked lines – at least for awhile. If you have old sewer lines and have fast-growing trees around, you may want to consider hiring a plumber do a video inspection of your lines periodically (think of it as a colonscopy for your house). If there’s a problem the plumber will be able to pin-point where it’s at and (hopefully) fix it before it becomes a major expense.

Tree terrors continue

You might remember back in October 2009 I gave one of the first Friday quizzes. The featured tree had epicormic shoots, and Monday’s answer revealed the neglected wire staking that was slowly girdling the main trunk. (Be sure you click on those links to see what the tree looked liked in 2009.)

I thought you might be interested to see what this tree looks like now:

A picture is worth a thousand words….many of those unprintable.

Update January 2022 – in response to a reader question, here is the tree in 2019 thanks to Google maps.

Unspeakeable Acts of Pruning

(Hey, I think it’s Tree Week on the GP!)

Our land has a nice buffer of big, old oaks, hickories, and maples between us and the two-lane highway. Power and phone lines thread through the middle of them. Thus, I have nightmares about orange Asplundh trucks.

So with much concern, I noted that utility crews and
subcontractors have been out in full force in our rural area,
inexplicably leaving one tree and then “pruning” another.

OMG that's awful

I pulled over and snapped this latest atrocity last night. The power lines are to the right (not in photo). As this is only a mere mile or two from our property, I may sit at home on the porch next week with the shotgun in my lap.