The Garden Professors™ – Page 96 – Advancing the science of gardening and other stuff since 2009

Lasso those grasses!

While Jeff and Bert were swilling beers and eating burgers last weekend (dang, wish I was there to commiserate!) I was whacking back the last of the perennials and grasses in our home garden. Tarp after tarp were filled with winter’s debris for compost pile as we fought 25 mph gusts the entire time. Not ideal conditions. However, a neat trick I learned years ago came in handy with the grasses. I’m assuming many of you utilize this technique also – so forgive me if this is a “nothing new” post Here’s Paul and Dabney, our Hahn Horticulture Garden horticulturists, demonstrating said technique:

Just cut below the web strap or rope with your favorite implement of destruction, and toss the whole bundle on the tarp to get it to the pile. Note that they both have on safety glasses, and Dabney has on gloves. I can’t stress enough the importance of gloves (and long-sleeved shirts) when handling dried grasses. One of our student workers sliced his finger open to the tune of three stitches last week. He was cutting down Arundo donax, Paul asked him to put some gloves on, but since 22 year-old guys are indestructible, he blew off the advice. Just saw him working out in the garden today with gloves on, yay!

Weigh in with YOUR garden clean-up tips – ’tis the season (for most of us north of USDA Zone 7 in the northern hemisphere).

Garden Professor Trivia #2: Who’s the tallest GP?

[This could get interesting…Oldest! Weirdest! Heaviest drinker! Most traffic tickets! Most cats! Most obsessed with slugs! etc.]

Keep Calm and Carry On…

This past weekend GP Jeff Gillman and I were in Midland, Michigan for two different conferences and had a chance to catch up over dinner (Boulevard burgers – best in Midland) and a couple of cold Bell’s stout ales. It was nice to visit with Jeff since we have so much in common but rarely get to see each other. As you might suspect, our conversation centered on negotiating the perils of the tenure and promotion process at research intensive universities, dealing with bumbling administrators, and, of course, our fellow Garden Professors. Quick Garden Professor trivia: Who’s the shortest Garden Professor? (Answer below).

Another item we discussed is how frantically worked up some people about following the various landscaping ‘rules’, especially for tree planting.

I have a program that I do on soil amendments. I present 6 or 7 examples from about 30 studies that I’ve collected from the literature that show that amending backfill when planting trees provides little, if any, value. Invariably, 2 or 3 audience members race up to podium after the Q & A, veins popping out of their foreheads.

“You have to add compost/peat/hydrogel/cow manure/take your pick when you plant!” they sputter.

I counter, “No you don’t. I just showed you a half dozen examples where it didn’t matter; if I had time I could’ve shown you two dozen more.”

The conversation usually turns one of two directions from there.

“Well, I saw a gardening expert on TV and they said you always have to add compost/peat/hydrogel/cow manure/take your pick when you plant.”

The other variation is: “Well, I always add compost/peat/hydrogel/cow manure/take your pick when I plant trees and shrubs and they do great.”

“Did you try any without the compost/peat/hydrogel/cow manure/take your pick? ”

“No, why would I? They always do great when I add compost/peat/hydrogel/cow manure/take your pick !”

As part of the soil amendment talk I present some data from a tree planting study which also included a comparison of width of the planting hole (1.2 times the width of root-ball, 2x root-ball width, and 3x root-ball width). After three years, width of planting hole had no effect on shoot or diameter growth. At this point in the talk I wait ten seconds before I move on to allow the results to sink in. By the time the next slide hits the screen half the audience is in a state psychologists refer to as ‘cognitive dissonance’.

People just can’t get over it. Another race to the podium after the talk, “But you have to dig the hole 3 times the width of the ball.”

“Can if you want to, but I wouldn’t say have to.”

“But, but…”

Clearly, there are things that shouldn’t be done when planting trees, like planting too deep. But a lot of things we “know” are based on what sounds right, on what feels right; not necessarily on science. Many practices have worked their way into extension bulletins, fact sheets, and our communal knowledge through sheer repetition. Often times, these are things that won’t hurt the tree (adding amendments or making a wider planting hole) but make the job harder than it has to be.

Point is, we need to take a deep breath, get a grip, and be careful with absolutes like ‘never’ and ‘always’. Working with trees is a lot like working for a university; it requires a high tolerance for ambiguity. Trees are living dynamic organisms that are able to respond and acclimate to their environment. I’ve stated many times that trees often grow more in spite of us than because of us. So calm down and carry on.

GP Trivia answer: At a hair over 5’8”, I am the shortest GP.

The roots of the rhody problem

There were several good shots at analyzing Friday’s unhappy rhododendron. Mature leaf size can be determined by light levels, as both Lisa B and Tom & Paul suggested. Moving a plant from a low to high light environment could cause this change in leaf size. This rhododendron hasn’t been recently transplanted, however, so we can eliminate light levels as a cause. (And there was no other impediment to light, such as the presence of shading plants.)

Lack of nitrogen was mentioned as well; but a lack of nitrogen would have resulted in chlorosis in newer leaves as well as smaller leaf size. In this case, the new leaves are not chlorotic. (The chlorosis on the older leaves is probably a phosphate-induced iron or manganese deficiency.)

Foy alluded to issues with water…and indeed that’s what I believe is happening with this rhododendron. Plants that exhibit smaller mature leaves in subsequent years are often limited by water. Full turgor is needed to force leaves to expand fully; without this physical pressure from inside, leaves fail to expand and once cell walls have lignified, leaf expanion ceases.

Lack of sufficient water during leaf expansion could be related to irrigation, though in our wet spring climate this is rarely a factor. More likely is a problem with the roots themselves. Definitive diagnosis would require digging up the plant to find out whether its roots are still encased in clay and burlap (my guess) or if something else is restricting their ability to grow beyond the planting hole.

Friday puzzle: unhappy rhododendron

Today we have a diagnosis question. Consider this unhappy rhododendron:

While there is more than one problem with this poor thing, the one I’d like you to think about is why the newer leaves are smaller than the old leaves. (They are fully mature.) There are two parts to this question:

1) What is the physiological reason that the leaves are smaller? (In other words, what is directly causing this difference?)
2) Knowing this, what does this tell you about the underlying problem? (This is related to diagnosing what’s happening in the landscape that you could actually see if you knew where to look.)

I hope that’s not too confusing! I’ll monitor the blog over the weekend and add clarification if I need to.

Answer on Monday!

Random thoughts from the NW Flower and Garden Show

Last week was Seattle’s NW Flower and Garden Show. This multi-day extravaganza features display gardens, educational seminars, and many opportunities to spend $$$. I had a little free time one day and shot some pictures, which I present here along with my commentary:

The Good

The “perfect” lawn is no longer just a monoculture of grass. At least two of the display gardens had flowers scattered for a designer version of ecoturf:

And a very cool repurposing of old heating vent covers as part of a patchwork of groundcovers:

The Questionable

A gorgeous Japanese maple (Acer palmatum), “born” in 1893:

I’m sorry. I have a real problem with digging up 108 year old trees for a garden display. I would be surprised if this tree will survive its relocation, wherever that might be. (Perhaps there was an explanation for this that I didn’t see, but mature trees should be moved only if absolutely necessary.)

I also wonder about the ethics of digging up a 700 year old alpine spruce (Tsuga mertensiana). I’m a fan of salvaging plants on sites slated for development, but somehow I doubt the Canadian Cascades are being threatened with condos.

And things that make you go hmmmm…

Pot…socks? Diapers?

Blackberry vines as tree decor

Off-label Use of a Chicken*

[Extremely] Preliminary research results from the University of Maryland indicate
chickens may be of interest in the fight against Halyomorpha halys, the brown
marmorated stink bug.

There are good stink bugs and bad stink bugs. The brown marmorated stink bug is a bad one. A relatively new introduced pest, it is piercing, sucking, and generally ruining vegetable and fruit crops (as well as some ornamentals) across a good part of the U.S. There are apparently few natural predators for this imported species and they reproduce like mad, thus the potential for this to become a very serious economic issue. USDA funding has appeared, and scientists are working against the clock on every angle of the problem.

Dr. Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses at the UM Central Maryland Research and Education Center, is among them. He is not only a great entomologist, but a total hoot, just like several other bug people I know. He’s doing plenty of conventional research as well as loads of critical Extension service spread out over several states. As an orchard and nursery owner, he also has a personal stake in the issue.

I had the pleasure of hearing about Dr. Gill’s latest work at a recent nursery association meeting. He related the severity of the problem as well as several stink bug-related research projects he’s involved with, but the one that really caught my attention was his work with chickens.

On a tip from a gardener/hen owner, Dr. Gill decided to explore further. In a nutshell: the stink bomb hidden in the thorax of Halyomopha species is a terrific defense mechanism against bird and reptile predators. But chickens seem to be immune (and unconcerned about their breath). Actually, not a big surprise – I’ve caught my hens eating some pretty amazing/disgusting things. His preliminary study consisted of a few borrowed hens in a couple of nice little fresh-air pens, free to scratch about. A request to some battle-weary local gardeners yielded tupperware containers full of brown marmorated stink bugs. Through some feeding trials, he found… a hen’s capacity for stink bugs knows no bounds.

The hens had access to their regular feed, but gobbled up all the stink bugs offered. I can’t recall the exact quantity, but it was A LOT.

Stink – it’s what’s for dinner.
Action photo courtesy of Dr. Stanton Gill, University of Maryland.

The hens would only go for the stink bugs if they were active. Dr. G. put some in the freezer (stink bugs, that is), rendering them immobile, and the girls turned their beaks up. Once thawed and moving (!!!), they became dinner.

Finally, he worked with a food scientist to answer what should now be a burning question – did the eggs taste funny? Blind taste tests found that participants preferred the eggs produced by the stink bug-eating hens versus controls. I believe further studies may be in the works, as well as some publications relating his findings.

* Ha, ha, I kid!!! This post is neither an endorsement nor recommendation of the research described within. There is no MSDS available. No REI. No PPE guidelines. No EPA approval. No acronyms at all, actually. You’re on your own.

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.

Mystery teeth revealed

Friday’s puzzle was tough! Several of you were on the right track – this is a carnivorous plant. Right away Deb suggested a pitcher plant (then got sidetracked with chestnuts), but Derek was spot on with his guess of the “spiky bits” on a Nepenthes pitcher:

What the function of these spiky wings are is not clear to me; I did a little checking in the literature but failed to find anything convincing. It does seem to suggest a close relationship with fly traps. Perhaps the ancestral type was a fly trap type plant, which eventually evolved to an enclosed pitcher? (Perhaps someone out there has a better grasp of carnivorous plant evolution than I do?)

And the scientific name? Nepenthes alata, or “winged Nepenthes.”

Thanks for playing!

Friday mystery teeth

I’ve spent most of this afternoon at the NW Flower and Garden Show. During my visit, I snapped a photo of this toothy plant part:

So the questions for today are….

What is this plant part?
What plant did it come from?
(And if you know its scientific name, that actually answers both questions at once.)

My husband is convinced this is too small a part of the plant for anyone to figure out the answesr. I’m sure someone will prove him wrong!

Answer and a larger photo on Monday.

Breaking up Tree Week with an Important Announcement! (Or Not — depending on how you feel about shameless plugs)

OK, here it is, my one and only shameless plug — because my publisher says: Hey! You need to at least let people know that the book exists!

So — I’m excited to say that my next book, How The Government Got In Your Backyard, which I co-wrote with my good friend (and old college roommate) Eric Heberlig, who is an Associate Professor of Political Science at UNC Charlotte, is finally out.

In case it isn’t immediately obvious, I love to write. This is my fourth book — and in many ways I think it’s my best. In it Eric and I look at the science and politics behind a number of environmental issues — everything from Plant Patents and Illegal Plants (think marijuana) to Organic Food, Global Warming and Biotechnology. We look at the political right and left, investigate the science behind what they believe, and try to give unbiased opinions. Some people have already let us know that we’re wrong! (Which we find amusing — but that’s another story).

What we don’t try to do in this book is make up your mind for you — that’s your job based on your priorities.