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Oh Deer! Part 2

Last week Holly and I extolled the virtues of our dogs for helping to keep our gardens and landscapes relatively deer-free even though we live in areas with high deer pressure. Of course, letting dogs roam your property is not an option for everyone. So what are some other options to keep deer from turning your garden into a salad buffet?

My former grad student, Sara Tanis, shows off deer damage at her parent’s place near Ludington, MI

One of the most popular non-canine deer remedies is applying various deer repellants. Typically I’ve been pretty skeptical of deer repellants. Trying to stop hungry deer from chowing down on your garden is like trying to stop a high school football team from devouring an all-you-can-eat pizza buffet. Recently, however, I saw some results from some colleagues at North Carolina State University on the effectiveness of various deer repellents in Christmas tree plantations that looked promising. Deer damage is a major issue in Christmas trees; deer browse pressure can be very high on conifers since they may be the most palatable thing available to deer in the winter. Research at NCSU and other studies (Wagner and Nolte 2001, Wildlife Soc. Bull.29:322-330) indicate that repellants that contain putrescent egg solids or animal protein can be effective at reducing deer damage. Of course, no repellant is 100% effective. If they’re hungry enough and don’t have an alternative, deer will likely overcome their fear of these scents and still come in for a nibble. Also repellants need to be re-applied periodically to be effective. Nevertheless, for gardener’s at their wit’s end and ready to resort to high velocity lead, repellants may be a better alternative. Although Sara says lead works too!

When history and good stewardship collide

One of my colleagues emailed me a couple of pictures last week taken in Puyallup, WA. As you can see, there’s a trellis supporting a massive old trunk…

…and crown…

of an ancient Hedera helix ‘Baltica,’ a cultivar of English ivy.

For those of you not in Washington or Oregon state, English ivy is a designated noxious weed. Thousands of dollars and hours of labor are spent on removing this species from forested areas in Washington state, where it crowds out native species and increases tree failure simply through the weight of vegetation. It is not a well-mannered ornamental in our climate.

So why, you may ask, is this particular English ivy prominently displayed and obviously cultivated? Chris Pfeiffer (my colleague) found out that it had been planted by Mrs. Ezra Meeker, wife of the founder of Puyallup, over 140 years ago at their original homestead. It is part of Puyallup’s cultural history and is considered a heritage “tree.”

But as you can see in the second photograph, the ivy is in flower and presumably will set seeds, thus contributing to the invasive problem. I don’t know enough about the City’s management plan for this specimen, but I doubt it includes removal of the flowers before seed set.

So what should communities do in situations like this? I think the city needs to remove the flowers, though this would be a labor intensive activity. But it would only take one person a few hours to hand prune the flowers.

I’ll be curious to hear what you all think, and whether you have seen similar collisions between historical significance and appropriate plant choices.

Confessions of a Weather Channel Addict

My name is Bert and I’m a Weather Channel junkie. It started innocently enough; sneaking an occasional peek at the local radar. Then I found myself sticking around for the next Local on the 8’s just for the smooth jazz. The progression from there was steady and predictable: Glued, trance-like, to the couch for re-runs of ‘Storm Stories’ and ‘When Weather Changed History’; setting my alarm 20 minutes early to catch ‘Wake up with Al’ so I could get my morning Stephanie Abrams fix. My downward spiral was further enabled by weather.com. I knew I needed help when I found myself checking the local radar to see if it was raining instead of just looking out the window.
Admit it. If you’re a gardener or work with gardeners, you’re probably hooked too. Hard to imagine a Saturday or Sunday morning that doesn’t start with tuning in to TWC or clicking on weather.com. The local radar and weather warnings, of course, are indispensible. We had a frost advisory in our area last night and I’m sure some folks will get an extra couple weeks out of their annuals if they paid attention and got them covered.

An often-overlooked feature on weather.com that I encourage gardeners and landscapers to use is the wind forecast. If you go to your local hourly forecast and click on ‘details’, it provides an hour-by-hour forecast for local wind conditions. This is a great way to plan any herbicide applications (e.g, Round-up or Weed-B-gone) you may be contemplating. Doing a little planning and spraying when conditions are calm is one of the best ways to avoid off-target injury.

So clearly there are plenty of reasons to keep us hooked and tuning in, even if some aspects of TWC are getting just a little too predictable:

Studio anchor: And now we go to Jim Cantore, who’s on the Outer Banks where Hurricane Holly is about to make landfall. Jim, what’s the latest out there?

Cantore (braced against a gale but looking studly in his official Weather Channel raingear): Well, just like the other 73 hurricanes I’ve been in, it’s raining. And the wind is blowing really, really hard!

Cut back to studio anchor: Thank you, Jim, for that insightful report.

The Weather Channel, live by it.

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Can cultivars be considered native plants?

One of the questions that arise in discussing native plants is the question of whether ornamental cultivars (e.g., ‘October golory’ red maple) can or should be considered ‘native’. In short, my answer is ‘No.’

Here’s my rationale on this. First, when we think about natives we need to put political boundaries out of minds and think about ecosystems. Political boundaries – a ‘Michigan native’ or ‘an Oregon native’ – are meaningless in a biological context. What’s important is what ecosystem the plant occurs in naturally. In addition to taking an ecological approach to defining natives we also need to consider its seed source or geographic origin. Why is it important to consider seed origin or ‘provenance’? Species that occur over broad geographic areas or even across relatively small areas with diverse environments can show tremendous amounts of intra-species variation. Sticking with red maple as an example, we know that red maples from the southern end of the range are different from the northern end of the range. How are they different? Lots of ways; growth rate, frost hardiness, drought tolerance, date of bud break and bud set. Provenances can even vary in insect and disease resistance.

Native range of red maple

If we’re dealing with an ornamental cultivar, do we know the original seed source or provenance? Sometimes yes, sometimes no, sometimes maybe. Think for a minute how most ornamental cultivars come to be. Some are developed through intentional crosses in breeding programs. The breeder may or may not know the geographic origins of the plants with which they are working. Or they may produce interspecfic hybrids of species that would not cross in nature. Some cultivars are identified by chance selection; an alert plantsperson finds a tree with an interesting trait (great fall color) in the woods or at an arboretum. They collect scion wood, propagate the trees and try them out to see if they are true to type. If the original find was in a native woodlot and the plantsperson kept some records, we may know the seed source. If the tree was discovered in a secondary location, such as an arboretum, it may not be possible to know the origin.

So, if a breeder works with trees of known origin or a plantsperson develops a cultivar from a chance find in a known location AND the plants are planted back in a similar ecosystem in that geographic area, we can consider them native, right? As Lee Corso would say, “Not so fast, my friend.” We still need to consider that matter of propagation. Most tree and shrub cultivars are partly or entirely clonal. Cultivars that are produced from rooting cuttings; for example, many arborvitae, are entirely clonal. Cultivars that are produced by grafting, like most shade trees, are clonal from the graft union up. The absolute genetic uniformity that comes from clonal material is great for maintaining the ornamental trait of interest but does next to nothing to promote genetic diversity within the species. From my ultra-conservative, highly forestry-centric perspective, the only way to consider a plant truly native, it needs to be propagated from seed and planted in an ecosystem in the geographic region from which it evolved. Few, if any, cultivars can meet that test.

The New Evidence Against Glyphosate

This past week Susan over at Garden Rant asked me about a paper which she had recently read which “proved” that Round-up caused birth defects. This study was interesting because it took embryos of chickens, exposed them to glyphosate (the active ingredient in Round-up) and then looked at the problems which the embryos had. Indeed, there were problems at concentrations of glyphosate much lower than what you’d see in normal agricultural applications. This is similar to other studies which “prove” how toxic glyphosate is which have been conducted over the years where various types of cells have been removed from human bodies, exposed to glyphosate, and then the resulting cellular damage has been taken as an indication that this herbicide is incredibly dangerous to us.

Studies where embryos or cells removed from the human body are tested against poisons have a glaring weakness which needs to be appreciated before we go off the deep end thinking that they prove that glyphosate is killing us. They’re conducted in a system that isn’t at all natural. That’s not to say they have no importance, but it’s like saying that, because it’s known that an air bubble in your bloodstream will kill you, air is dangerous. Or like saying that, because salt injected into your bloodstream is deadly, you shouldn’t eat it. Both air and salt can be deadly if they are in your bloodstream above a certain level, but we need to be careful to look at the specific situation with which we are dealing and take that into account when we make our judgments about how toxic particular things are to us.

I can’t argue that glyphosate can be toxic to people. This morning I did a little literature search on it and actually found cases where people had committed suicide by drinking agricultural formulation of glyphosate – mostly in the Eastern world. It would be a nasty way to go too – you’d need to ingest a lot of the stuff and the primary problems would be that parts of your gastrointestinal system would be corroded. Ouch!

If you’re going to use a glyphosate herbicide use it carefully and in accordance with its label. Don’t go splashing it around willy-nilly. Don’t drink it. Don’t get it on anyone. Don’t use more than you need to. To do any of these things is not only dangerous, it’s also stupid. That said, I can’t find any reason to think that glyphosate is anything but what it appears to be – an effective weed killer that is on the safer end of the spectrum relative to other chemical weed killers (and here I’m including organic weed killers too – Ever been exposed to those 20% acetic acid vinegar herbicides? I tried one this summer — Just being near it made my eyes burn.)

How to Kill Buckthorn

Last year we completed a small research study on how to kill buckthorn. If you live in the upper Midwest then you’re familiar with this plant as a shrub which has escaped cultivation, been spread by birds, and generally made a nuisance of itself, particularly at the edges of forested land.

Buckthorn is notoriously difficult to kill after it gets more than about a foot high. It laughs at single applications of roundup. If it’s pulled out of the ground any roots that don’t come with it have a good chance of sprouting shoots themselves, and it seems to enjoy being treated with organic herbicides like vinegar. So, to try and kill bucktorn, we used an herbicide which had the active ingredient triclopyr. This is an active ingredient which is usually great against all manner of weedy vines like poison ivy. This herbicide is labeled for homeowner use and is available in most garden centers.

We applied this herbicide to buckthorn in the spring, summer and fall, and we used a few different application methods including painting the herbicide onto cut stumps and spraying it onto the leaves of uncut bushes, as well as painting the product onto the lower portion of stems. Some of these application methods were experimental. Do not attempt to apply an herbicide in any way besides that which is listed on the label!

That said, we found that the fall was by far the best time to apply the herbicide and that spraying the foliage wasn’t nearly as effective as other application methods, particularly painting the cut stem with the product after cutting it down.

Sheet mulching – benefit or barrier?

Alert reader Matt Wood pointed out a recent article in the NY Times on mulching with newspaper and wondered about my take on the topic.

For use on landscapes, I do not like sheet mulches of any stripe. They tend to hinder to air and water movement, most especially in unmanaged landscapes like restoration sites. A classic example is the use of cardboard or newspaper covered with wood chips. The chips are easily dislodged, exposing the sheet mulch which quickly dries out and becomes hydrophobic. Thus, the roots of desirable trees and shrubs lose out on the water, while the weeds surrounding the edges of the mulch benefit from the runoff:

Published research on sheet mulching in landscape settings confirms the drawbacks of sheet mulching. But the article in the NY Times is about vegetable gardens. This is a different situation – more akin to agricultural production than to landscape horticulture. Vegetable gardens are routinely managed during planting, thinning, weeding, and harvesting. Newspaper sheet mulches in these situations rarely dry out and, when kept buried and moist, do break down quickly.

So – keep the sheets on the (vegetable garden) bed where they belong!

Another W.O.W.

We’ve been beating up nurseries over Why-Oh-Why (W.O.W) do they sell things like Scot broom. Here’s one of my favorite W.O.W’s from the landscape side (Homeowner division).

Why-oh-Why do people think grass clippings make a good mulch?! This photo comes from near my home. The homeowner put the clippings down about two months ago. All the trees were dark green and healthy before the clippings were put down. Note how chlorotic the trees in the middle have already become and the dead lower limbs where the trunks were covered. We’re all for mulch but this ain’t it!

Are Fertilizer and Insecticide Spikes a Good Idea?

One of the products that I often hear gardeners raving about are their fertilizer / pesticide combination spikes which are supposed to not only feed your plants, but also kill all of the insects which attack them. I, personally, have not used these products, but I’m generally the kind of person who says “If it works for you then keep using it”. Still, these spikes bug me a little. Here’s why.

First of all I should point out that I’m not opposed to fertilizer spikes by themselves. I’m a little concerned that fertilizer should be spread out instead of concentrated in one place, but still, I don’t consider them that bad. The insecticides used for these spikes is where I have the problem. Once upon a time these spikes were made with a chemical called disulfoton (aka disyston) which is bad news. It’s a water soluble chemical which is highly toxic to people. If you have an old package of fertilizer / insecticide spikes around there’s a good chance they were made with this chemical. Do yourself a favor and get rid of them. This stuff is really toxic and not to be messed with. On the other hand, if you’ve purchased fertilizer / insecticide spikes recently, then the active insecticide in those spikes is probably imidacloprid. Imidacloprid is a mixed bag when it comes to safety. It’s not nealy as toxic as disulfoton, but it’s not non-toxic. It has been banned in Europe for a variety of reasons, the most important of which seems to be that it was implicated in the collapse of bee hives (imidacloprid is systemic insecticide so it will get into a plants pollen where honey bees could eat it). At this point it hasn’t been ruled out as having something to do with hive collapse here in the states — though if it does have a role it does not seem to act alone. It can also affect other beneficial insects who feed on pollen. Additionally, it has been known to control some pests while allowing mites to go crazy — in fact, it may even increase the rate of mite egg laying.

But imidacloprid is an effective insecticide which works against a wide range of insects which you that you might find on your plants. It is much safer than many of the older systemic insecticides, and it isn’t readily translocated to fruits (a problem that many people are concerned about with systemic insecticides is the movement of these insecticides into the fruit itself where it can’t be washed off — Imidacloprid is translocated to fruits –just not that much — it moves in the xylem and fruit takes up mostly phloem).

So these spikes are one of those things that I’m wary of. Not to say you shouldn’t use them, but be aware of what they are and what they could do before you buy them.

Volunteering for duty

One of the advantages of having a couple acres (and not being especially fastidious about weeding) is that sometimes you get your landscape plants for free. I always keep an eye out for interesting plants that may turn up on their own – or a least get left behind by our bird friends. Here are some volunteers that have shown up recently at Daisy Hill farm that I’ll work into the landscape.

Sassafras (Sassafras albidum) are notoriously difficult to transplant. I’ll leave these sassafras volunteers where there are and relocate the shrubs in the bed. I’m looking forward to some awesome fall color in a few years.

The native range of redbud (Cercis canadensis) only extends into the southernmost counties of Michigan but they generally do fine here in the Lansing area (just north of the end of the native range). We have an old redbud in the front of our house so we get volunteers from time to time. This one is on the edge of our patio so it’s easy to keep an eye on. I’ll let it grow on another year or so and then find it home.

Most people probably wouldn’t get too excited about eastern redcedars (Juniperus virginiana) showing up on their own. When I was with the US Forest Service, my grad student and I did research on seed germination of eastern redcedar and Rocky mountain juniper (J. scopulorum). Ironically they can be difficult to grow as seedlings in nurseries because the seed are doubly dormant (they have a tough seed coat that requires scarification and the embryo is dormant and requires cold stratification). I’m planting conifers as a screen on the south side of property. I’ll move these guys and a couple of their friends in the spring.