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It’s raining, it’s pouring, it’s a good time for a site assessment…

April is turning out to be a soggy month for most of Michigan and our surrounding states. While most homeowners are inclined to hunker down indoors and keep an eye on their sump pumps on these dark, dreary days; our current run of wet weather is a good opportunity to take a stroll around your property and make some notes. In particular, note any areas where water is accumulating.

Poor drainage is one of the most common sites factors that limit landscape tree and shrub survival and growth. Sites that retain water for more than a day or too after rains stop are especially problematic. The challenge with wet areas is we usually wait to plant trees and shrubs until things are high and dry and it’s easy to forget where the wet spots are.

There are two primary strategies for establishing healthy trees and shrubs in flood-prone spots. First, determine if the problem can be corrected. In some cases homeowners may be able to re-direct water flow from downspouts or other sources to keep water form accumulating in one spot. Again, these kinds of problems are easiest to spot if you go out when it’s raining. Re-grading the area or installing drain tiles are other options but these are usually require skills and equipment beyond the average do-it-yourselfer.

If correcting the drainage issue is not an option, the second strategy is to plant trees or shrubs that are tolerant of flooding. Plants vary widely in their tolerance of soil flooding and, not surprisingly, trees and shrubs that grow naturally along riverbanks and other low areas are usually the most tolerant.

This low spot in my yard was a good site for a Baldcypress

There are numerous resources on flood tolerant trees and shrubs on the web. Two of the better resources are from the Morton Arboretum and from Cornell University. Please note the Cornell guide is a large (>6 MB) .pdf file.

These Michigan holly (Ilex verticullata) I planted a couple of years ago a doing fine even though they are periodically flooded each spring.

Wet areas on your property do not have to be a ‘dead zone’, but establishing trees and shrubs in low laying areas takes some planning. The first step in the process is assessing your site and identifying the problem areas. The best way to do this is to put on a raincoat and take a walk in the rain.

Applying pesticides when you don’t mean to

I’d rather we didn’t use them, but I see their value and I appreciate what they can do for us when they’re used properly. One of the things that I hate about pesticides though is that, even when they’re used correctly, sometimes they can come back and hurt us in ways that we don’t expect. You have probably heard that you should not use grass clippings where herbicides have recently been used as a mulch because they could injure them. This is mostly because of the pesticide 2,4 D and other, similar herbicides for the lawn which can injure other plants if placed in the wrong spot.

Back in 2011 the herbicide Imprelis was used on many yards, especially in the Midwest, and did a lot of damage to spruce and other trees as Bert has mentioned in previous posts. We had thought that we were nearing the end of the effects that this herbicide would have, but now I’m not so certain (see Bert’s post from March 25). Recently questions have been asked about whether this stuff might last longer than we thought in compost. A few months ago I probably would have said that I doubted that Imprelis would linger long in compost, but, in part because of how long its effects take to show up on some plants, now I’m not so sure, and there are others who share my concerns (in fact, it was these guys who pointed out the possibility of compost problems with Imprelis to me). I honestly don’t know whether compost that includes trees that were treated with Imprelis (or has Imprelis in it for some other reason) would or wouldn’t be harmful to other plants, but I do know that it’s something I’d be watching out for.

Worm Juice!

There’s still snow on the ground, but I know that spring is finally coming to Minnesota because I FINALLY saw a crocus peeking its head out of the ground this week!

So perhaps you wonder from time to time what garden professor types get excited about. Well, here’s an example. Tomorrow I’ll be meeting up with a friend of mine, Meleah Maynard, which is nice, we always have a good time chatting, but I’m especially excited because she’s bringing me some drippings from her vermicomposting. Hooray, worm juice! I’ll be taking it to the lab and then running some tests on it to see what it has in it in terms of nutrients. After I get the results in a couple of weeks I’ll give you the information (maybe even compare it side by side with urine – that would be fun!)

The invisible, insidious presence of heavy metals

I spent the last two weeks in Spain, combining business with pleasure. It’s interesting when something that starts out as part of the pleasure ends up being business instead.

Charlotte translated this sign for me – it’s historical information. Note the brightly colored mine tailings in the background.

My daughter is teaching English in Mazarrón, a small town in the province of Murcia. The climate there is very similar to southern California, though drier and not as warm: it’s pretty much a scrubland ecosystem. Since we both enjoy hiking, we decided to take advantage of exploring the abandoned mine sites. Unlike such sites in the United States, there are no restrictions to hikers and in fact there’s signage explaining the history of the mines. This is a popular hike after a rainstorm because of the unnaturally red pools that form in the landscape.

The abandoned mine works; these buildings are over 100 years old, though this area was mined since Roman times.

It took some Internet research to find out that lead, silver and zinc were the minerals of interest extracted from these mines. For those of you who aren’t aware of how ore processing works, it includes adding various chemicals to crushed rock to solubilize and isolate the desired minerals. The leftover tailings are nearly always highly acidic and full of environmentally available heavy metals. The various metal oxides and sulfides that formed at Mazarrón are vividly red, orange, and yellow, and there is a pervasive sulfur smell throughout the site. If this isn’t hell on earth, I don’t know what is.

Mountains of mine tailings

So it was really quite a shock to both of us that not only could we walk into this mine site, but that there were no warnings regarding exposure to whatever toxic chemicals might be in the soil and water. We took pains not to touch anything – but others were not so cautious. Some hikers ahead of us watched their dog cavort through the largest of the pools, and later took photos of each other on the mine tailing spoils.

Visitors and dog and red pool of ????

Yes, the dog went in the water

And then a photo op on the side of Spoils Summit

This hideously beautiful landscape was unearthly, primarily because there was absolutely nothing alive in it. No plants, no insects, no birds. Along the edges of the mine tailings there were spring flowering shrubs, bees, and birds, just as one would find elsewhere in the region. (But not in the spoils. What an apt name…)

A blood-red seep into the pond

Crystals forming as water dries in the pools

Just off the side of the tailings, life continues

How do the mines of Mazarrón fit into gardening? Unlike this mine site, where the evidence of heavy metal contamination was clearly visible, it’s not so obvious in our garden soils. The residues of arsenic-containing pesticides, leaded gas, zinc from car tire wear, and other possible contaminants are unseen and unknown unless we have soil tests done to confirm their presence or absence. Yes, it can be expensive to have these tests done, but if we are handling our soils, breathing the dust, and eating the plants that grow there, wouldn’t it be smart to find out what’s there first?

WARNING: This post contains graphic content

As many of you know, numerous homeowners and golf courses in the Midwest experienced substantial damage to trees, especially conifers as a result of application of Imprelis, a new turf herbicide that was released by DuPont in fall 2010. If you do a google image search for ‘Imprelis’ you can see lots of photos of the typical damage we observed in summer 2011, when most Imprelis damage became apparent. The usual symptom of Imprelis exposure were brown, twisted and stunted shoots or trees killed outright.

White pine killed by Imprelis – July 2011. Photo: Bert Cregg

Shoot damage – July 2011. Photo: Bert Cregg

Today, however, I received some images from an Extension Educator in southwest Michigan that turned my stomach. So what happens when trees that weren’t killed by Imprelis try to resume growth? The results are not for the feint of heart.

‘Club-like’ shoots – March 2013. Photo: Beth Clawson.

‘Tumor-like’ growths at the ends of shoots – March 2013. Photo: Beth Clawson.

Imprelis damaged shoot cross section – March 2013. Photo: Beth Clawson.

Master Gardener Researchers Rule!

The Garden Professors test new products all the time. Fertilizers, pesticides, tree wraps,compost tea, etc., they’ve all found their way into our fields and greenhouses at one time or another, but still, we can’t test everything, it’s just not possible. New stuff comes out all the time, and it’s impossible to keep up, so one of the things we love to see is people who take the initiative to test things themselves. Recently we got to see the results from a group of Master Gardeners who tested biochar on growing vegetables. The results aren’t final yet – there’s still a few years to go – but I love the fact that this is occurring and I can’t wait to see more.

Long winter proves that climate change is a hoax

Just looked at the forecast for the week – Thursday’s forecast high temperature is 32 deg. F. This is a far cry from last year’s record-shattering 86 on the same date. Clearly all this blabbering about climate change is just a bunch of hysterical nonsense.

As sportscaster Lee Corso would say, “Not so fast, my friend…” While winter 2013 can’t compete with winter 2012 in terms of record-breaking warmth, this winter has continued a trend which may have profound implications for landscape and garden plant selections.

As you’ll recall, last winter saw the release of a new USDA Hardiness zone map which indicated that most areas of the US had warmed by at least one-half hardiness zone (5 deg. F) since the previous map was produced 22 years earlier. Hardiness zones are based on average minimum temperatures; in other words, what’s the coldest temperature you’re likely to see in a given winter. As it turns out, minimum temperatures have been warming faster than overall average temperatures. So much so, in fact, that one researcher declared the brand new hardiness map dead on arrival. Nir Krakauer at City College in New York noted that if we look at trends, rather than averages, many areas of the US are already another half a zone warmer than the new USDA map.

Minimum winter temperatures are warming at a much faster rate that average temperatures

Last week I gave a presentation at the Minnesota Shade Tree Shortcourse and pulled together some cold hardiness data for the Twin cities. According to the new USDA map, Minneapolis-St. Paul is now zone 4b (-25 to -20 deg. F). One way to think of this over a long enough time-span, about 1/3rd of their winters should reach a low in that range, 1/3rd should be slightly warmer, and 1/3^rd should be slightly colder.

The new USDA map indicates the Twin cities are in zone 4b

I pulled out the winter weather records for Minneapolis-St. Paul since 2000, including winter 2013. In the past 14 winters temperatures in the Twin cities have dipped to their hardiness zone level exactly once, 2004. All other minimum temps were at least 5 deg. F warmer.

Annual minimum temperatures at Minneapolis-St. Paul airport (MSP) have reached zone 4b levels only once since 2000.

Obviously a 14 year record is not sufficient to build a hardiness map. Nevertheless, if someone tries to use this winter as proof that climate change is hoax; just remember, minimum winter temperatures – the temperatures that serve as a primary limit of which plants can grow where – tell a different story.

Must we continue to bring in exotics?

A couple weeks back I posted about a collaborative research project that I am involved with to identify seed sources of two Mediterranean fir species (Turkish fir and Trojan fir) for use as Christmas trees in various locations around the country. The post prompted a question from Monta Zengerle who asked, “Must we continue to bring in exotics to satisfy the nursery trade?” Since our intended purpose is Christmas trees and people move plants around the world for purposes other than nursery stock, I’ve broadened the question to “Must we continue to bring in exotics?” for this discussion.

Not all exotic species introductions are man caused. This dock washed ashore in Oregon following the Japanese tsunami carrying all kinds of critters with it.

The answer, of course, is “No.” As human beings the only things we absolutely have to do are eat, sleep, and breathe. But the reality is much of the food and fiber production around the world, as well as our amenity plantings, are based on exotics plants. Human agricultural history is largely the story of plant importation and subsequent breeding. As Thomas Jefferson famously observed, “The greatest service which can be rendered any country is to add a useful plant to its culture.” However, it is doubtful that Jefferson considered kudzu or purple loosetrife could be among those plants added to our culture. Today we have a different understanding and realize that along with the economic benefits of plant exploration and importation comes the possibility of unintended and serious ecological consequences. And we’ve realized this for some time. People that deal with plant introductions on a regular basis talk about ecological errors and economic errors. If we allow importation of a plant that later turns out to be ‘bad actor’, we’ve made an ecologically harmful decision; if we ban a useful plant that ultimately would have turned out to be non-invasive, we’ve suffered an economic loss. Fortunately, only a small percentage of exotic species become naturalized and only small percentage of naturalized species become invasive. The underlying challenge is we cannot predict with 100% certainty which plants will be invasive in a new environment and which won’t. Ecologists are working on it and we can certainly begin to judge the invasive potential of new introductions. In the meantime, we are left with the imperfect calculation of whether the potential economic upside outweighs any potential environmental risk.

‘Top-work’ on noble fir in Oregon to maintain a single terminal leader. Turkish fir typically require less top-work.

So let’s look at our current project as a case study. What’s the upside? Christmas tree growers in the U.S. produce roughly 20 million trees annually. That’s a potential economic impact of hundreds of millions of dollars and seasonal and full-time employment for workers on over 13,000 farms from North Carolina to Washington State. A major issue for growers in virtually all of the principle growing regions is phytophthora root rot. Previous work at Oregon State University indicates that Turkish fir is highly resistant to this pathogen. By identifying seed sources with phytophthora resistance and superior Christmas tree characteristics (tree form, needle color, post-harvest needle retention), we will enable growers to continue or expand production and give consumers an additional choice for their holiday tree.

Native noble fir (left) is highly susceptible to root rot. Turkish fir (right) is much more resistant.

What’s the down side? As I mentioned, predicting invasiveness is difficult. That said, firs have several characteristics that make them unlikely invaders. Most firs have a relatively long juvenility period (age before they produce seed) which means they have a long period between generations. Secondly, most fir species produce seed crops sporadically as opposed to producing heavy seed crops year after year. Ecologically, firs are pretty wim
py; growing best on moisture, well-drained sites and unlikely to aggressively colonize disturbed areas. Lastly, the best predictor of invasiveness is invasiveness – a plant that has become invasive in one location is a candidate to become a repeat offender in a similar environment. Among conifers, the greatest issues with invasives have been pines (genus Pinus), in the southern hemisphere. In fact, all of the documented cases of invasives in the pine family (Pinaceae) are Pinus species; none were Abies. Based on all this, the likelihood of Turkish fir or Trojan fir becoming ecological problems appears very small, while the potential to add a useful plant to our culture is clear.

Exotic giant sequoias at Hoyt arboretum, Portland, OR.

Richardson, D.M. and Rejmánek. 2004. Conifers as invasive aliens: a global survey and predictive framework. Diversity and Distributions 10:321-331.

Rime and Reason

This weekend I got to take a leisurely drive to the northern end of Michigan’s Upper Peninsula with my daughter so she could check out Michigan Tech University. Lots to see along the 488 mile drive from DeWitt to Houghton, including a moose, lots of snowmobiles, and the world famous ‘Yooper tourist trap’. (For the uninitiated, people that live in the U.P. are known as Yooper’s, while those of us that live beneath the Mackinac Bridge are known as ‘Trolls’) Once we got along the Lake Superior side of the U.P. we drove through a short section of freezing fog that produced rime on the surrounding forest. Our tight schedule and road conditions prevented me from stopping to get photos but I found several on Wikimedia commons that illustrate the phenomenon.

Here’s a recent TV weather blog that provides some additional photos and information rime and hoar frost, which is a related winter weather phenomenon. Rime forms when air temperatures are below freezing drop below the dew point as the water condenses and freezes, the ice crystals accumulate on the windward side of trees, fences, and other objects. Another similar phenomenon is hoar frost. Hoar frost looks similar to rime but is lighter and not associated with freezing fog. It forms when surfaces cool below the dew point and ice crystals accumulate. Here are some examples of hoar frost we experienced a couple years ago here at MSU.

Good Stuff

Boy oh boy, what a fun day! People yelling at me from the left and from the right. But hey, I didn’t start doing what I do to make everyone happy. With that said….Nah, I don’t feel like attacking anyone today. Instead, let’s look at a good renewable fertilizer: Cotton seed meal. It’s got a reasonably good ratio of nitrogen to phosphorus and potassium — slow release of course. Basically a waste product given a meaningful purpose. And look at the label — no mycorrhizae or other gimmicks. Just pure, unadulterated, cotton seed meal. This is what I want on my garden.