Friday puzzler addendum

OK, I know we gave you a tough assignment for the weekend, so I want to post something fun as well.  (Think of this as dessert after your healthy meal!)  Take a look at the photos below:

This hedge is regularly sheared and no one part of it has been maintained any differently than another part.  Both sections of the hedge face east, and the damage is anywhere from 2 to 4 feet from the ground.  What do you think has caused the damage?

Explanatory photos reveal all on Monday!

Friday puzzler: Opening a can of worms

Part of being a Garden Professor is evaluating, interpreting, and passing on good science to the rest of the gardening world.  I was recently made aware of two articles soon to be published in Crop Protection and Pedobiologia, both peer-reviewed, scientific journals.  (You can download these articles just by clicking on the highlighted journal names.)

Briefly, what one expects from a scientific article is (1) a statement of the research question (the hypothesis) to be investigated, (2) a clear description of the materials used and procedures followed, (3) a listing of the results, along with their statistical significance, and (4) a discussion of the results, including whether they supported the hypothesis.

    

Both articles focus on the use of vermicompost teas as a way of reducing pest damage on greenhouse grown crops.  If you’re not familiar with this product, it’s made using worm castings and water in an aerated system. The researchers conducted one large experiment and divided the results into two parts for publication. Therefore, the materials and procedures were the same for both articles, and you’ll also see that the conclusions are likewise the same.  (My point – you really only need to read one of these articles.)

 

I sent these articles and my evaluations to my GP colleagues; at least two of us will be sending letters to the editors of both journals expressing our concerns.  Jeff thought these articles provided a great opportunity for our blog readers to look over our shoulders and see what we do.  We don’t question the results that the investigators got, nor do we have any argument with the statistical analysis.  We do question the authors’ interpretation of the results.

So here is your assignment for the weekend:

(1)  Read the methods section carefully to understand the differences between the treatments (the vermicompost tea addition) and the control. Can you think of an alternative reason for the results the researchers found?
2)  What additional flaw do you see in the discussion section in terms of the proposed mechanism of protection conferred by the vermicompost tea treatment?

On Monday, I’ll post the draft of the letter that we’ve drafted to the journals.

Oh, and if you have any questions, please post them!  We will answer them the best we can.

Inspecting nursery plants, part ll

Well, I’m recovering from this simply horrific chest cold or whatever it is and feeling brain function returning.  The last time we were at our virtual nursery, we were looking for root flare and inspecting the trunk for damage from improper bagging.  Since we’re already down on our hands and knees, let’s consider roots.  In general, you really don’t want to SEE roots, except where they meet the trunk (the root flare).  The presence of coyly crossed “knees” in this photo is a clear indicator of a plant that wasn’t potted up quickly enough:

Likewise, while the fused, circling woody root mass in this next photo might be aesthetically interesting, it sure doesn’t make a functional root system:

It’s pretty easy to avoid these types of plants, because you can see the root problems before purchasing.  The hidden root problems, such as those I’ve shown in earlier posts, are tough to find until (or if) you take all the extraneous stuff off of the root ball.

Finally, there is a new production practice that really fries my potatoes.  What really makes me angry is that these trees had absolutely LOVELY roots – a nice flare, woody roots spreading radially – and then they were butchered – and left unprotected:

 

I can think of no legitimate reason for this practice.  I’ll be curious to hear my colleagues’ thoughts, as well as those from the blogosphere.

Veggie gardening science – whaddya know?

I just had a long conversation with Michele Owens (of Garden Rant fame) about vegetable gardening.  This isn’t one of my strong areas, either professionally or personally (I do have containers of herbs, but that’s as far as it goes).  But what piqued my curiosity was her revelation that the vegetable gardening is just as full of myths and misinformation as my field of ornamental landscaping.

I’ve ventured into the realm of vegetable garden science now and then, especially in reference to having soil tests done before planting edibles (good!), the use of CCA-treated timbers (bad!), and companion planting (silly!).  Beyond that I haven’t given the topic much thought.

          

(You know who loves you know who!)

So, readers, what gardening practices out there need to be screened through the sieve of science?  Jeff and I have both written about many practices and products, but as you know our expertise is more on the ornamental side.

(Forgive my short blog today.  I’ve had some kind of chest crud since last Friday and I’m still wiped out.)

I see the light!

Here’s the follow up picture from Friday’s puzzler:

As you can see, there’s a street light near the lower half of the maple.  (I cleverly hid it behind the utility pole in the first photo.)  The green part of the tree never received the message that days were getting shorter, since the street light is bright enough to interrupt the dark period necessary to initiate dormancy.

This is one of my favorite phenomena unique to urban environments.  It doesn’t appear to hurt the tree, although the green leaves will die before the tree can scavenge their nutrients.  If more of the tree were affected, I’d be more concerned.

Congratulations to Planting Oaks, who nailed this right off.  And kudos to those thoughtful alternative explanations, all of which could logically have had an impact on color change.

Autumn color puzzler

Here’s a photo I took in Buffalo about 20 years ago.  Buffalo, like many places in the northeast part of the country, has fantastic color changes in the fall.  This maple seems to have changed its mind part of the way through the process:

What do you think caused part of this tree to retain its green leaves?  Answer and another photo on Monday!

Inspecting nursery plants, part 1

I’m frequently asked to give seminars on selecting healthy plants at the nursery, especially trees and shrubs which can run hundreds of dollars.  (Nobody seems to want a seminar on how to pick out a flat of petunias.)  I routinely visit nurseries with my camera so I can record examples of good and not-so-good choices.  What better forum to share these than on our blog?   I’m also curious whether the problems we see in the Pacific NW are found elsewhere in the country, or in the world for that matter.  So today we’ll hunker down on our hands and knees and inspect root flares.

The root flare (or root crown) is the point where the trunk meets the roots and should be wider than the rest of the trunk.   The photo below shows this clearly:

In balled and burlapped trees and shrubs, you might not be able to find the root flare as soil and/or burlap cover the root flare.  The tree below is burlapped far above its root flare:

Over time, many trees and shrubs buried too deeply will develop trunk rot.  You can inspect for rot by gently peeling back the burlap from the trunk and looking for damage.  Don’t worry, this doesn’t hurt the root ball or the trunk:

The tree in the above example already has some red flags – the presence of weeds on the soil surface suggests that it’s been in this pot for a long time.  (And no, you don’t want to buy this tree.)
The most dramatic example of the problems that can occur is this weeping larch, which has been completely girdled by the rot induced by the burlap and twine around the trunk:

Lesson:  It’s cheaper to wash your now-dirty pants than it is to buy (and eventually replace) a poor quality plant.

Mysterious tree failure exposed!

end about the tree failure question!  Many of you zoned in on an important point visible in the two photos I shared.  The tree’s base was obviously quite narrow where the trunk broke, and with the tree’s vase-like architecture this led to breakage. But why was the base so narrow?

Again, several of you thought about root issues, such as a restricted root zone, or possible damage to the lower trunk.  Actually, it’s a combination of root and trunk issues, as this last photo shows:

Tree failure 3

What we have is a large circling root (you can see it at the soil surface to the left and right of the trunk) that has girdled the trunk completely and prevented it from growing in diameter.  The trunk above this point continued to grow, eventually creating the instability that eventually led to failure.

This tree used to be the focal point of a small urban landscape.  It was planted about 15-20 years prior to failure and obviously had poor roots.  It irks me that the industry cannot figure out a way to (a) produce trees with decent roots and (b) plant them correctly.  No wonder so many ISA-certified arborists are now recommending that people only purchase bare-root trees, so that these heart-breaking scenarios are avoided.

Congratulations to Jimbo in Australia for being the first to identify this particular problem, and honorable mentions to those of you who had logical and realistic diagnoses for tree failure.

(I hate to take pleasure out of the fact that girdling roots are a significant source of tree failure in Australia, but Jeff and Bert give me so much grief about root washing that I was starting to wonder if it was only the Pacific NW that was cursed with this problem.  Guess not!)

Mysterious tree failure…

Here is this week’s plant puzzler.  This mature tree just fell over one summer day.  There had not been any significant wind, the soil was well-irrigated (but not overly wet), there had been no construction work or other root-zone disruption.  There were no significant pest or disease problems.  I’ve posted two photos from different angles, and will show one more photo on Monday.  Why do you think the tree failed?

Seattle Chainsaw Massacre

In the spirit of the season I’m including some photos from our neighbor’s willow tree that failed a few years ago.  The failure wasn’t unexpected, given the age of the tree and the lack of crown care it received.  What’s truly scary is the “tree service” that came out to deal with the problem.  Low bid wins again!

(And yes, I’ll post a puzzler as well.  Two for one today!)

Here’s the willow after the crown collapsed

Rickety ladder + chainsaw = suspense!

Standing in the collapsed crown – no rope or other safety equipment

 

Look Ma!  One hand!!!

And best (worst?) of all, the remaining trunk was just left in place.  It quickly resprouted and now resembles Cousin Itt from The Addams Family.