Bert Cregg

Fall color time…

Did you ever know one of those annoying people who always talks about how great everything is back wherever they were from; the kind of folks that make you want to say, “If things were so much better there, why are you here?” I have to confess I’m one of those people. No one’s ever actually given me the “If things were so much better there” line, but I’m sure my Michigan friends have been tempted. I’m warming to things Michigan but I suspect in my heart of hearts I’ll always consider myself a Washingtonian.

That said, there are some ways that Michigan has Washington beat. We have long, lovely sandy beaches where the water gets warm enough to swim in; which for me means at least 75 deg. F. Washington has great beaches, of course, but you’ll never see anyone over the age of 12 in the water without a wetsuit – even in August. We have real thunderstorms spring, summer, fall and occasionally even thundersnow in the winter! Western Washington is lucky to have two or three bouts of muffled thunder each year. And we have real fall color thanks to red maples, sugar maples, oaks, sassafras, tulip poplars and others. Conifers dominate the Northwest and what few large hardwoods there are (big leaf maple, red alder, black cottonwood) drop their leaves inconspicuously without much fanfare. Vine maples try to make up the difference but usually just add a splash of color here and there.

As with many states with rich fall color, “leaf peeping” or “leaf looking” is a popular fall pastime and many people plan fall getaways to northern Michigan to enjoy the color show. For someone in a position like mine, that means calls from media, AAA, and others asking for predictions on whether we’ll have good fall color. Of course it’s difficult to predict since conditions during fall itself (i.e., sunny days and cool nights) are among the biggest determinants. We do know that drought conditions late in the summer can result in early leaf drop or limit production of some secondary pigments, resulting in a shorter and more muted display. For us in Michigan that suggests a below average fall color show up North since many counties have received 50% or less of their normal rainfall since July.

For those interested in learning more about fall color, I high recommend ‘The Fall Color Guy’ website http://biology.appstate.edu/fall-colors The site is maintained by Dr. Howie Neufeld, Professor of Plant Physiology at Appalachian State University. Howie and I crossed paths at the University of Georgia when he was a visiting scientist and I was a Ph.D. student. He provides some of the best information I’ve seen on the science of leaf color and his essays on the website are good reads.

Pop quiz answer

Today’s post is a follow-up to yesterday’s quiz on foliar fertilization. I asked our blog readers to match the needle nitrogen content of Nordmann fir trees with the fertilizer treatments they had received.

Nutrient deficient Nordmann fir

The correct order is:

1)      control: no fertilizer 0.98%
2)      soil applied controlled release fertilizer 1.70%
3)      foliar nitrogen fertilizer 1.14%
4)      soil applied fertilizer + foliar feed 1.91%

While the foliar fert had a small effect, it’s important to note that, from a statistical standpoint, foliar fertilization did not significantly increase needle nitrogen concentration. Moreover, foliar feeding alone was not sufficient to overcome the nitrogen deficiency of the control trees. The main effect was from fertilizing the soil (actually container substrate is this case).

The take home message is that plants have evolved (or God designed them, if you prefer) to take up nutrients from the soil through their ROOTS. They’ve been doing it for millions years and have been getting along quite nicely, thank you. No matter how slick and clever the marketing, attempts to ‘short-circuit’ the process such as foliar feeding or trunk injection are short-term solutions at best or, as in this case, almost totally ineffective. Foliar feeding and trunk injection treat symptoms, not causes. Plant nutrient deficiencies occur because: 1) an element is lacking in the soil or 2) because the plant can’t absorb enough of the element (e.g., iron chlorosis). Effectively dealing with a plant nutrient problem requires understanding which of those two situations is occurring and why.

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…

Just for ewe: An alternative approach to weed control.

As I mentioned in the last post I was in Austria this past week for the International Christmas Tree Research and Extension conference. We hold these meetings every two years for Christmas tree researchers in Europe and North America to get together and share the latest research on various aspects of Christmas tree production and marketing. In addition to research presentations the programs also include tours of local Christmas tree farms, which is always the most interesting part of the conference.

In Austria one of our tour stops was an organic Christmas tree farm operated by Regina and Michael Spenger. For the most part, my views on organic systems are in line with those that Jeff Gilman has voiced here on the GP blog. There are certainly benefits in reducing pesticide use but it’s not a given that an organic approach is always superior to a conventional system. Nevertheless one hallmark of organic production is that growers must be creative and often develop innovative approaches to production issues. This is especially true when it comes to weed control; one of the most difficult challenges of organic growing. Good weed control is essential in Christmas tree production since grasses and broadleaved weeds are aggressive competitors for water, nutrients and light. To control weeds without herbicides the Spenger’s settled on a novel idea: Sheep. Each morning they release a herd of 40 Shropshire sheep into a plantation and let them munch away. The sheep are allowed to graze for a week and then rotated into another field. Shropshires are well suited to the job since they graze readily on the grass and forbs but leave the trees alone. The Spenger’s also get some small additional returns by selling a few lambs each spring as well as some wool. Obviously this approach has limitations but it certainly highlights important aspect of the organic movement that can benefit all production systems: looking at problems in a different way and thinking creatively.

The sheep herd heading out to a plantation to start their day’s work…

To say that sheep grazing in an Austrian plantation creates an idyllic scene is an understatement.

Marketing naturally grown Christmas trees.

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If it’s Monday this must be Austria…

Just a quick post from on the road. My family and I have been traveling through Europe the past week and a half. A bit of a whorl-wind trip combining some vacation and work travel. We started off a week and half ago, flying into Frankfurt. We rented a car and drove to Paris where we spent a couple of days sightseeing. Then it was off to southern France to visit friends that run a bed and breakfast there. This weekend we drove from France to lower Austria where I am attending our biennial International Christmas tree Research and Extension conference. I’ll have a few bits to report from the meeting later but for now I’ll just close with a few random acts of Horticulture from France.

Trees shaped like boxes…

Trees in boxes…

Horsechestnuts. Europe is big on horsechestnuts. Unfortunately most of them are scorched to a crisp and look like crap.

Pollarding. Europe is big on pollarding. Occasionally it’s done well and creates some neat effects. More often, like here, it’s done poorly and just makes a mess.

A green wall. Green roofs and green walls can help to reduce urban heat island effect. This green wall is mainly for show, I think. It’s made up of ferns and other mesic plants and requires constant mist irrigation. Not exactly a sustainable system, but it is dramatic and certainly commands attention.

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Toxic mulch: When shredded bark goes bad

We typically think of mulching landscape beds as a good thing. And it usually is; helping to conserve soil moisture, reducing soil temperatures and contributing to soil organic matter. Recently, however, I received an e-mail from a local landscaper that reported severe damage to annuals and perennials in a landscape bed immediately after applying hardwood mulch. The problem, sometimes referred to as ‘sour mulch’ or ‘toxic mulch’, occurs when mulch is left is large piles and undergoes anaerobic conditions. This results in the production of acids and other compounds that can volatilize when the mulch is placed in beds, especially during hot weather. These vapors can quickly damage annuals and other sensitive plants. Mulch in this condition is often characterized by a ‘sour’ smell. If you suspect your mulch has gone sour, spread it out before use to allow toxins to dissipate and water thoroughly either before or immediately after application. The University of Arkansas Extension has a nice fact sheet in the subject “Plant injury from ‘sour’ wood mulch.http://www.uaex.edu/Other_Areas/publications/PDF/FSA-6138.pdf

Fried Gerber daisy

Sedums are usually pretty tough…

And, yes, I did steal the title of this post from one of my all-time favorite ‘Far Sides’…

This Bud’s for you…

Ask the risk of honing in on Jeff’s turf, I thought I’d pass along this article by former University of Maine associate dean (and apparent Garden Professor wannabe) Katheryn Olmstead. It seems that Dr. Olmstead’s painstaking research has documented a preference among slugs for domestic beers, particularly Budweiser. http://bangordailynews.com/2011/07/21/living/garden-slugs-prefer-budweiser-over-foreign-brands/ Like most undergraduate students, it seems slugs prefer domestic swill to more refined imported brews; confirming many suspicions about both slugs and undergrads. Although we’ll have to wait for the full peer-reviewed article, her scientific method seems sound, including use of replicated plots. That said, her admitted qualms about being seen purchasing two six-packs in the same week raises doubts about Dr. Olmstead’s eventual rise to the rank of full Garden Professor

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.

Does native matter?

We’ve had lots of lively discussion on my post regarding the Mark Davis et al. comment in Nature on natives and exotics. I have been traveling and otherwise occupied and have not had a chance to comment so I feel a little like the kid that kicked the anthill and then ran away. Fortunately, Holly was gracious enough to forego her post today (I promise to return the favor, Holly!) so I can chime back in.

Obviously there are lots of layers to the debate but one of the main items in the discussion is whether there is an inherent ecological advantage in planting natives over exotics. At this point the focus always seems to shift to herbivory and the question of whether native insects will eat non-native plants. There are certainly examples each way; some insects are generalists while others are highly specific. More importantly, however, plants fill many other roles in the environment beyond serving as food for insects. Moreover, species composition is just one aspect of diversity. The ecological function of landscape is also determined by how we manage other factors such as structural diversity and age class distributions. In his book “Bringing Nature Home” Doug Tallamy shows a picture of a bland, sprawling suburban landscape ( p. 24) and notes “this highly simplified community is made up of a few species of alien ornamental plants that provide neither food nor shelter for wildlife.” OK, I’ll buy that. But would the situation change if the blue grass was changed to a native grass kept mowed to 2” and the two widely spaced shade trees were changed to natives? Doubtful. The structural complexity; that is, the number and arrangement of grasses, annuals, shrubs, and trees, is likely a bigger driver of ecosystem function than whether the plants are native or exotic.

In his thoughtful comments on the blog post Vincent Vizachero sums up, “I stand by my view that the general heuristic of favoring native plants over alien plants is better than the alternative of not caring about origin at all.” I can buy that as well, but with the caveat that other factors are equal. The rub, of course, is that other factors are rarely equal. And I suppose this is where the pragmatic approach discussed by Davis et al. resonates with me. In my position I do a lot of programming on trees for urban and community forests. I go through a list of criteria to consider for tree selection. Here are some of the key factors I usually discuss:

Adaptation There is no argument that there are well-documented environmental, economic and social benefits to trees in urban and suburban areas. But in order to fulfill these roles trees must be able to survive where they are planted. This means being adapted to abiotic and biotic environmental conditions which are often adverse. In this region of the country there are some native trees that fit the ‘tough trees for tough places’ bill, such as swamp white oak, bur oak, and honey locust. Many other natives, especially understory species, are much more difficult to site.

This street planting in Lansing alternated green ash and Norway maple.

Available space This seems like a no-brainer, but it’s amazing how often this gets overlooked and we end up with too much tree and too little space. Again, we have some great small native trees; Carpinus, redbud, striped maple. But these can be limited in their site adaptability.

Ash stumps

Diversity In Michigan some communities have lost 30% of their tree cover to the emerald ash borer. Have we learned our lesson about improving species diversity? Not really. But we need to keep trying. Exotic pests are here and here to stay. Does anyone believe that global trade will decrease in the near future? Does anyone believe that there will be quantum leap in our ability to detect and intercept hitch-hiking pests? In order to continue to accrue the benefits of urban and community forests we need to continue to diversify our portfolio; this includes a mix of natives and exotics. I doubt there will ever be sufficient data to prove one way other, but it seems reasonable to me that an urban and community forest balanced among 20-25 native and exotic species will be better able to withstand the slings and arrows of weather and pests better than one made up of 8-10 natives.