This site is for people who like plants -- growers, enthusiasts, aesthetes, novices and professionals, those who appreciate wild things and those who appreciate the cultivated. I garden in Chelsea, and I've been visiting people's yards for 20+ years in the course of my work. My goal is to make this blog a community project, so if you share my interests, please consider becoming a participant and contributing content -- Guerin. Info: greenstreet@mindspring.com

Friday, July 31, 2015

Surprising Appearance of a Chinese Yellowhorn

Nobody could figure out what it is.

images courtesy Steve Goebel Jr
A small tree growing across the street from the Jefferson Market in Ann Arbor. Bill Dale, a tree worker employed by the City of Ann Arbor, spotted it and brought a sample back to the office. He and co-worker Steve Goebel Jr were completely flummoxed, and asked for help from the community of "tree professionals" like me. Alternately-arranged pinnately-compound leaves, huge 'tropical' fruit with very large seeds. I had no idea. In the next couple of days, people suggested a wide range of possibilities until certified arborist Isaac Finn Dunigan of Grand Rapids came up with "Chinese yellowhorn."

In my world, finding a completely unrecognizable novel woody plant growing in a public space is so rare that it, like, never happens. But there it was cataloged in Michael Dirr's fantastic Manual of Woody Landscape Plants: Xanthoceras sorbifolium.

"Striking tree or more often large shrub, virtually unknown in commerce and gardens, zones 5-8, introduced via the Plant Select program at Colorado State University." Roasted seeds reportedly taste a little like macadamia nuts. In the mostly tropical Sapindaceae family, which now includes maples and horse-chestnuts.

Methinks the big payoff is the flower. Never seen it, but I've got to have one. 

Image is ripped from the headlines World Wide Web. Thank you Kew Gardens.





Thursday, July 30, 2015

Avoid falling for tree and shrub pest control scams

The following article was released by Michigan State Extension this week. It is the result of a complaint from a certain tree-care worker who was getting tired of responding to calls from worried customers. The customers had been advised by a mega-lawn-care representative that their trees/shrubs had pest issues requiring multiple spray applications. Said tree-care worker had to drive around town, checking the trees, and assuring the customers that there was no issue.
 
Posted on July 28, 2015 by David Smitley, Michigan State University Extension, Department of Entomology

It looks like we are seeing a new pesticide treatment sales scam. Most of the complaints so far are from Michigan’s Ann Arbor-Ypsilanti area, although everyone should be alert for this scam that involves a scare tactic about a non-existent or unimportant pest.

It works like this: A sales representative from a lawn, tree and shrub care company visits your yard and fills out a report. On the report, spider mites or another pest is circled and a warning is hand-written, “Spider mites are damaging your trees. A miticide treatment is highly recommended.”

The reason a scam is suspected is because one arborist in the Ann Arbor, Michigan, area has had six of his customers call him after they received this warning. When he investigated, he could not find any spider mites or damage at any of the six locations. Sometimes the sales person will leave a little Zip-lock bag with the report, like they did at my house about 15 years ago. It contained a leaf with a hole in it, and the warning, “You have gypsy moth. A spray is highly recommended.” When I looked at my trees, I had a difficult time finding any leaves with holes in them, and when I did, it was caused by a cankerworm, not gypsy moth.

A few holes in tree leaves are completely harmless. In fact, a pesticide spray would probably cause more harm than good because it will disrupt the predators and parasites providing natural control. We don’t usually see problems with spider mites in the yard and garden unless an insecticide, like carbaryl, is being sprayed. Carbaryl and some other insecticides can kill the predators that usually keep spider mites under control, but spider mites may be resistant to the insecticide and thrive in the absence of predators.

Arborists and responsible landscapers dread hearing about this type of scam because it makes their industry look bad. This is very unfair to a landscaping and tree care industry consisting of 99.5 percent responsible business owners. In fact, the last time we had this type of scam, the local branch manager of the company promoting the scam said it was due to a “rogue employee” that had not completed training and was going against their company policy. In my opinion, if a sales representative finds 10 customers in one neighborhood that have spider mite damage, the manager should investigate to see if this is a real or imaginary problem.

If you are looking for real spider mite problems, read “Pests in Gardens and Landscapes: Spider Mites” from UC Davis, and see the attached pictures.




Spider mite damage in roses. Photo by UC Statewide IPM Project

Wednesday, July 29, 2015

Why it is generally a bad idea to put gravel in the bottom of a pot and how that relates to evolutionary biology

Even experts will sometimes advise putting a layer of gravel in the bottom of a plant pot: "for drainage." What you get in reality is a smaller pot. Think about it: if a soil is saturated such that it can hold no more water, it doesn't matter whether the bottom of the medium is a bunch of rocks or a single hole, it's gonna blow. If the soil is less than fully saturated, the water molecules will stick around in the nice spongy soil, just as a moist sponge will not leak all over your kitchen counter. The gravel does nothing.

OK, I get it, lesson learned, big deal and so what?

For one, a certain percentage of healthy plants bought from the nursery will die from drought when planted out, even if "watered" regularly. To understand this, consider that the texture* of the soil of a root ball of a balled-and-burlapped plant is invariably different than the texture of the soil into which said tree is being planted.

If the soil of the root-ball is clay, and the soil into which is being planted is sand or gravel, and if you are not mindful when watering, the water will just rush through the sand and gravel, pretty much ignoring the tightly-wound ball of clay

Reverse situation: soil of b-and-b plant is sand and the soil of its new home is clay, the water will either drain right through and be absorbed by the fine clay particles. Or worse, the plant will sit in a clay-lined pool. Even given optimum moisture, the clay lining is tough for the roots of the sandy-balled plant to penetrate, and it's much easier for the roots to swirl around in the loose sand. 

So that's why you should try and match the two soil types by amending the parent soil.

But now the payoff. . . what plant on earth is adapted to germinating in one type of soil and then discovering that three feet away, in all directions, is a soil of an entirely different texture? I will submit: none. Or almost none. Because that situation does not exist in nature, and plants have never been subjected to that unlikely do-or-die evolutionary pressure. Crossing that abrupt texture barrier is just hard to do.

*texture refers to the size of the soil particles

Sunday, July 5, 2015

A Tale of Three Hedges


Hmm, what to do with an old hedgerow that has gotten out of control . . 

How about making art!

Interesting attempt here, but comically ill-advised. Only a couple of the juniper stems remain alive after a severe reduction/reshaping. Junipers need full sun, and they don't take well to even moderate trimming. Someone with very little knowledge exerted a lot of effort to accomplish something that was doomed to fail.

And then there is the blue spruce . .
Very odd choice for a low hedge, considering it strongly aspires to be a tall tree. This planting is only about five years old. To keep it low, the main leaders were recently cut off half-way ('topped'). Methinks this will suffice for a couple years, but it will soon be impossible to keep the branches from growing into the street without cutting off the green foliage and into bare wood.

This burning bush (Euonymus alata) will manage just fine after its recent haircut. Ideally one would cut back to just above the lateral buds, but sometimes down and dirty will suffice just fine.

With old shrubs and thick stems, one runs a risk that the plant will not tolerate a severe topping. The more vigorous the plant, the better chance of success.