Don’t worry…we’re still here!

I can’t even tell you how many months it’s been since I posted on the blog. It’s been a perfect storm for the four of us, with writing books (Linda), new jobs (Jeff), doing the Garden Professors gig in Toronto (Holly, Bert and Linda) and writing grant proposals (all of us). I am going to try my best to post once a week, even if it’s short and silly.

Something new to let you know…the blog will be moving to a new format in the near future. It will be a WordPress blog, which means it’s easier for us to post and easier for you to search. In theory, all of the old posts will migrate as well, along with the pictures and comments. We are all looking forward to a more user-friendly format.

In the meantime, take a look at the new portal to our WSU Gardening Webpage!

You can find the page by clicking here. We’re in the process of adding more material all the time, but you can be sure that whatever you find on this new page is relevant, peer-reviewed science for use by home gardeners.

Let us know what you think!

R U nuts?

One of the things that comes along with having an extension appointment at a major university is I get lots of calls and e-mails from homeowners on a never-ending list of sometimes bizarre tree topics.  Technically, my extension responsibilities are related dealing with professionals; such as arborists and nursery and Christmas tree growers, but the ‘consumer horticulture’ calls still find me.  Last week I received a voice-mail message from an excited gentleman speaking at a decibel level somewhere between rock concert and jet plane take-off.  From the disjointed and rambling message I could tell the gentleman was elderly and maybe disoriented or had just had a few.  After identifying himself he indicated that he wanted to learn where he could find a “pine-nut tree”.  Although he didn’t give it, I knew the man’s location from his area code.  A legitimate response to such calls is to redirect them to the individual’s local extension office, but I hate getting the runaround as much as the next person, so I usually respond when it’s something I can help with and in this case I could.

I dialed the number and the gentleman picked up right away.  He sounded just as he did in the voice mail; gregarious, slightly rambling, and VERY LOUD.  His story, however, made me glad I called back.   His father had emigrated from Lebanon many years ago and he remembered how his dad had always reminisced about eating pine nuts in the Old Country.  For years he had wanted to plant a “pine nut tree” in memory of his dad.  The problem was every time he went to a nursery and asked for a “pine nut tree”, nobody knew what he was talking about.

 


Pine nuts. Photo: Paul Goyette – Wikimedia commons

 


Pinus pinea cone. Photo: Luis Fernandez Garcia – Wikimedia commons

 

I explained to him that the pine nuts his father cherished were from stone pine (Pinus pinea) trees, which are the pine nuts (pignoles) favored for making pesto.  In the US, the pine nuts that are sold commercially usually come from pinyon pine (Pinus edulis), which is native the southwestern US.  Unfortunately, neither of those trees will grow in the Upper Midwest, where he lives.  I pointed out that there are many other pine trees that produce edible nuts – the main reason those two species are widely used is because they produce very large nuts making them relatively easy to harvest.  In fact, there are about 20 species of pine that produce seeds large enough that harvesting the nuts is worthwhile.  Two pine species that produce edible nuts and grow well in our area are Korean pine (Pinus koraiensis) and Swiss stone pine (Pinus cembra).  I include both in my recommendations for alternative conifers for Michigan.  I gave the gentleman some information on nurseries in his area that I knew carried those trees and he was excited to have some direction on his quest to renew his father’s memory.

 


Korean pine (Pinus koraiensis) at the University of Minnesota Landscape Arboretum


Swiss stone pine (Pinus cembra) at Hidden Lake Gardens in southeaster Michigan.

Sidenote: The heartbreak of ‘Pine mouth’.

Have you ever experienced a bitter or metallic taste that persisted for days, even weeks, after eating pine nuts?  Then you’ve likely experienced Pine Nut Syndrome or ‘Pine mouth’.   The cause of the disorder is not completely known, but research by an industrious graduate student in the Netherlands suggests that nuts from certain pines; particularly an Asian pine, Pinus armandii, are most likely to cause the issue.  So, if you are a pine nut fancier, learn what you can about your source.  Pine nuts supplies can be cyclical since pine nut crops are often subject to biennial bearing.  Soaring prices during poor supply years provide incentive for inferior nuts to work their way into the market.

Let’s get (soil) physical…

We’ve had quite a bit of discussion this past week on the FaceBook page regarding Kelly Norris’s article in Fine Gardening on dealing with clay soils.  While Kelly’s article mainly addressed selecting plants for heavy soils, there was a side-bar on cultural approaches to dealing with clays; including the standard advice to avoid adding sand to clays.  This advice has been around for years.  The first time I recall hearing it was from Dr. Carl Whitcomb when I took his Arboriculture class nearly 30 years ago (Fall 1984 to be exact).  The rationale that is usually given is that adding sand to clay is the essentially recipe for concrete.  Technically, of course, this is not entirely true since making concrete also requires cement.  Nevertheless, trying to amend a clay soil with sand can lead to more problems than it solves.  The fundamental issue is not that clay + sand = concrete.  After all, there are plenty of highly productive soils in nature that have various ratios of sand and clay and they don’t form concrete.  The bigger issue is that tilling a clay soil (which you’d have to do to incorporate added sand) leads to a loss of soil structure.

 

So, what is soil structure?  Soil structure is a physical property of soil that describes its relatively ability to form aggregates.  Unlike soil texture, which can be quantified as percent sand, silt, and clay; structure is a qualitative soil physical property.  Common examples of soil structure are granular, platy or blocky.

 

 

While we usually think of clay as a negative thing (“Geez Jim, my wife just told me you have clay, I am so sorry…”); a well-structured clay soil can have excellent properties for plant growth.  Well-formed clay aggregates (referred to as ‘peds’) in a granular soil can function very much like larger soil particles in terms of water movement and drainage.  Soil structure is one of those things you have to experience to understand.  About the best description I can come with is that peds in a well-structured granular soil often have the consistency and texture of Grape Nuts cereal.

 

There are also soils out there that are sometimes referred to a ‘structureless’ soils.  These include single-grained soils and massive soils.  Single-grained soils are essentially pure sand.  In West Michigan these occur near Lake Michigan and are often called ‘blow sands’.  We have several seedling nursery operations in these areas.  Since there is no clay these soils have almost no nutrient-holding capacity – growers have to manage their fertility almost as it were a soilless system like a hydroponic or aeroponic system.  The advantage of growing in these soils is it makes lifting bare-root seedlings easy. Massive soils, on the other hand, are very dense soils where particles do not show any evidence of aggregation.  Repeated tillage can result in loss of structure and a soil (or portions of the soil) may show attributes of a massive soil including crusting or formation of hardpan.  The example below shows how structure (indicated by % aggregation) is lost through repeated cultivation.

 

 

 

Effect of soil tillage on soil structure.  Source (Greacen 1958, Australian J. Ag. Res. 9:129-137).

What can be done to improve or preserve structure?  This is a case where less is often better.  Natural processes such as freeze-thaw cycles and the action of earthworms and other invertebrates work to loosen soil and create aggregates.  The tips in the Norris article (avoid overworking soil and adding organic matter) are essentially the same advice I would give.

A Tree Story

Given my line of work, it’s probably no surprise I’m a sap for tree stories (no pun intended).  Last week I was in Nova Scotia for the biennial International Christmas Tree Research and Extension conference.  The conference and associated tours provided an opportunity to learn about Christmas tree production in Nova Scotia, one of the leading Christmas tree producing regions of North America.  During the conference I also learned about the annual tradition of Nova Scotia’s Tree for Boston.

Each year Nova Scotia, through its Department of Natural Resources, presents a 40’-50’ Christmas tree (balsam fir, white spruce or red spruce) to the city of Boston.  The gesture is an annual reminder of Nova Scotia’s gratitude for Boston’s and Massachusetts’ immediate aid and generosity in response to the Great Halifax Explosion of 1917.  For those of you, like me, that were not familiar with the story, the Great Halifax Explosion occurred in Halifax Harbor on the morning of December 6, 1917.  The French Freighter Mont Blanc, packed with explosives bound for the Allies’ war efforts, collided with another ship and caught fire.  The explosion that followed, reported to be the largest man-made explosion of the pre-nuclear era, leveled a large portion of Halifax and neighboring Dartmouth, killing nearly 2,000 people and injuring 9,000 more.  Within hours of the massive explosion, the governor of Massachusetts sent two trainloads of relief supplies to the devastated city.  As a token of their appreciation, the citizens of Halifax provided Boston with a Christmas tree for Christmas 1917.

 

The tradition of providing a Tree for Boston was revived 1971 and has become an annual event ever since.  While the cynical may deride this as a crass and commercial promotion for tourism and Christmas tree exports, the gratitude and affection of Nova Scotians for Boston seems heartfelt nearly a century after the disaster.  And, if nothing else, Nova Scotia’s Tree for Boston serves as a history lesson, at least for those of us in the U.S., on this over-looked chapter of World War I.

 

Neon continued!

I’ll follow Bert’s highly informative, thought-inducing post with something not statistically significant. Hey, it’s summer.

My last post on ultra-bright “neon” plants had a comment from Sarah…

“I saw some iresine in a local garden center the other day, sun coming
through it at just the right angle, and the shade of blazing pink that
came through was basically every Barbie accessory I ever had. It just
seemed wrong somehow. Took a picture of it with my phone.” 

Aside from a hilarious (and insightful) comment, she included a URL to her photo.

It’s so good I had to post it. The pink plastic-y glow is amazing.


Fab photo by Commenter Sarah of Iresine herbstii – chicken gizzard plant

I had to greatly lower the resolution so that the system would let me post it. At full size and resolution, it almost hurts to look at it.

Incidentally, I’ve always thought “chicken gizzard plant” was a bit of a misnomer. I’ve seen really fresh chicken gizzards, and Barbie would NOT want accessories in that particular shade.

 

How to lie with statistics

I’m attending the American Society for Horticultural Science (ASHS) meeting this week in sunny (and hot) Palm Desert, CA.  Tomorrow I will be presenting some of the early results from the SOME-DED-TREES study.  For those that are new to the blog, SOME-DED-TREES is the acronym for the Social Media DesigneD TREe Establishment Study.  Last year, my students and I established a landscape tree study in which the treatments were suggested by Garden Professor’s blog readers.  Actually, we ended up installing two studies: one to look at fertilization at planting and one to look at impacts of mulching at planting.  The trees were ‘Bloodgood’ planetrees grown in 25 gallon containers.  In each study we divided the trees into three root treatments: We “shaved” the outer roots to eliminate circling roots; we “teased” apart the circling roots; or we just planted the trees as is (or “Pop and drop” to use Linda’s vernacular).

I reported some of the results of the mulch study here on the blog last fall and will include some of those data in my talk tomorrow.  I am also presenting some of the data from the fertilizer portion of the study.  One of the ways we assessed fertilizer response is by using a device known as a SPAD meter.

 SPAD meters have been around for a while and they are very useful.  The device measures light transmittance through a leaf, which is highly correlated with leaf chlorophyll content.  Chlorophyll content, in turn, is highly dependent on foliar nutrition so SPAD readings often provide a useful indicator of plant nutrient status. 

Here at the meeting I am using my laptop, which means I am without my usual statistical and graphing software.  So in order to plot some of the data for my talk I am relying on Excel.  This gets me to “How to lie with statistics.”  When I calculated the means for this June’s SPAD chlorophyll index values this is the chart I got.  Looks like a pretty impressive response to fertilizer, doesn’t it?

SPAD chlorophyll index of Planetrees fertilized at plant (Fert) and control trees (No).

The problem is the scale.  Note that by default, Excel truncated the scale on the y axis to values between 28 and 36.  This is a big no-no in scientific circles.  Graphs scales should include zero or show if break if there is some reason the range needs to be truncated.  The reason truncating the scale is a no-no, as shown here, is that it makes differences look proportionately larger than they really are.  Advertisers use this trick all the time.  Next time you see a bar chart in a sales brochure or magazine ad, look that the scale – bet it doesn’t go to zero. 

Let’s look at the chart after I re-scale it.  It still looks like there’s still something going on with fertilizer, but it doesn’t make you go, “Whoa!” like the first chart.

SPAD chlorophyll index of Planetrees fertilized at plant (Fert) and control trees (No).

As it turns out, there is a statistically significant effect of fertilizer on the June SPAD values.  However, this effect essentially disappeared by the time we re-assessed the trees three weeks later.  Here’s the final version of the data as it will appear in my ASHS talk tomorrow.

This brings up another issue we face in this kind of work; statistical significance versus biological or practical significance.  The ‘Fert: p<0.01’ on the slide indicates there is a 99% probability that the difference in the mean SPAD values between Fertilized and Non-fertilized trees on June 17 is not due to random chance or error.  But as the leaves continue to mature this effect essentially disappears.  Could the early season boost in nutrition be enough to give these trees an edge in the long run?  Possibly, but I wouldn’t say likely.  To date we have not seen any effects of fertilizer on growth but it’s still relatively early in the game. Tree growth is cumulative and effects that may be too subtle to detect early on may turn out to be significant later on. Stay tuned. 

Neon for your garden

Was wandering through Target on Monday for the first time in months.

Helloooo!? The 80’s called and wants its neon crap back.

Didn’t care for it then and certainly don’t care for it now. Though there is the increased safety factor of being highly visible at all times, whether in sunglasses or underwear.

But never mind my lack of style.

It made me think about a few plants that, if the light is right, certainly display that glowing, saturated color, found in the “Astro-Brite” pack of copy paper usually reserved for yard sales and such.

Close to dusk, the Kniphofia uvaria ‘Echo Mango’ in our garden stands out from 100 yards away.  Bred and selected by Richard Saul of Atlanta’s ItSaul Plants Inc., it is one tough perennial, taking heat and humidity with aplomb.

My experience has been one big early summer flush of blooms, with some significant reblooming until frost.  Best in full sun, it’s also drought tolerant and cold hardy to USDA Zone 5. It doesn’t get whopping huge like some other Kniphofia do – stays a nice manageble size, topping out at 3′ to 4′ tall.  ‘Echo Mango’ (or any other Red Hot Poker) adds a terrific bit of vertical interest to an otherwise mound-y mixed border.  Best with fellow warm colors. Pink, not so much.


‘Echo Mango’ = glowsticks!
Achillea ‘Paprika’ doesn’t go so well with it.  Mental note to relocate it in fall.


You can almost hear the sound of space lasers…
Eeee-yoooooo-eeeee-yoooooo…or maybe that’s just me.

 

 

Brace yourself

The photo below (graciously sent to me by former MSU Extension Educator Jennie Stanger) graphically illustrates the importance of removing ALL staking and supporting materials from trees once they are established.

 

 


Just a matter of time (Photo: Jennie Stanger)

In this case the stakes were removed but the strapping material was left around the tree.  Since this is a spruce, Jennie supposes no one wanted the prickly job of wading into the center of the tree to take off the strap.  Eventually the trunk was girdled and when the area recently experienced some heavy thunderstorms, the weak spot on the tree was exposed.

 

 


Stately evergreen to mangled mess (Photo Jennie Stanger)

As a general rule we recommend that all staking and support materials are removed within two years, preferably one year.  This type of damage is one of the prime reasons: after two years who is likely to remember that there is still strapping left on the tree?

The heartbreak of ‘Carrot-top’ syndrome

The perk of participating in a blog is you get a platform to vent on your pet peeves.  Recently I’ve seen several classic examples of ‘Carrot-top’ syndrome.  No, I’m not talking about the red-headed comic; though he tends to annoy me too.


Annoying Carrot-top #1.

The ‘Carrot-top’ I’m referring to occurs when white pine trees are sheared as Christmas trees but then planted as landscape trees.  The typical result is that the side and lower branches remain suppressed while the terminals go crazy.  I’m not sure why syndrome occurs in white pines and not other trees; it may be related to vigor of white pines and how hard the growers have to shear them to keep them in shape.

 


Annoying Carrot-top #2.

I love my friends in the nursery and Christmas tree industries and they work hard to grow quality trees, but this is one practice I’d like to see end.  And, to be fair, they are giving customers what they want.  If we set up a survey at a garden center and placed  a 7’ sheared white pine next to a 7’ white pine that had been minimally pruned, 19 out of 20 people would take the tree that had been sheared to look like a Christmas tree.  However, this is truly a case where less is more.

Going off half-cocked

The good news about being a landscape extension specialist is you get to comment on a variety of landscape tree problems.  The bad news?  You get to comment on a variety of landscape tree problems.  In an average week I probably get 10-15 tree-related calls or e-mails from homeowners, landscapers, growers, extension educators, lawyers, newspapers, and on and on.  Sometimes the problem is routine and obvious like tar spot on maples; “I have these spots that look like tar on my maple leaves…”  Sometimes the problem looks routine and turns into something else entirely different like the Imprelis herbicide debacle.  With the number if problems I respond to, invariable I sometimes end up shooting from the hip – and miss the mark.


Red maple with sparse canopy (right foreground).  Maple in left-center of picture across the road was planted at the same time.

A few weeks back I noticed some red maples on campus that were struggling as they were starting to leaf out.  There were planted about three years ago following a road-widening project.  They are located on a tough site between a parking lot and a busy 4-lane road.  My immediate diagnosis was they were weakened due to the aftereffects of last year’s sever heat and drought.  I even included a photo of them in an article I did for our on-line extension news.  Then this morning I happened to talk to a friend from our campus landscape services.  “Boy, those maples sure took a beating from the drought last year”, I volunteered.  My Landscape services friend replied, “Well, that and we hit them with Shortstop last year…” Uh oh, now the conversation was going in a different direction.  Shortstop is a plant growth retardant, the active ingredient is paclobutrazol, which inhibits GA synthesis in plants and is being widely used by arborists to reduce the need for tree pruning.  In this case it worked a little too well and the trees ended up being stunted.

Leaves of paclobutrazol-treat maple (left); untreated leaves on right.

In my defense, I was partly right.  Under normal weather patterns paclobutrazol applied at the labeled rates (as was done here) would have reduced shoot growth and leaf growth but clearly the drought exaggerated the effect.  So, another lesson learned (actually re-learned) never assume anything about trees until you talk to the people who actually take care of them.