Goldilocks & The Three Chairs

May-June 2010

PEOPLE OFTEN COME IN MY OFFICE and say, “How can you stand having so much stuff in here?” After 11 years, I decided it was maybe time to do something about it. So I cleaned out my office in early April. I was just finishing up when people starting coming in and saying, “How can you stand sitting on that chair?” Well, granted the chair upholstery is falling apart, so I conceded and promised to check with office surplus to see if there was something available.

For a number of mornings following, I would open my office door to find a “gently-used” office chair magically sitting in front of my desk. I would sit on it and whoosh, it would slide down until it reached the stage where I needed a couple of telephone books (what my parents considered booster seats when I was a kid) to work.

The next day, another well-wishing colleague would show up all smiles and giggles and I would open my office to find another nice chair… that sank down several inches until I was nose to nose with my keyboard. Seriously, where were they finding these chairs?

Finally, I mentioned it casually to our administration associate and she called me up, immediately ready to walk/roll a surplus used chair to my office – from across the street. So, what did I do to spurn all these lovely gestures? I honestly don’t know. I’ve been told I’m a good listener. I encourage people to speak freely and I try not to judge. I really do care about the people I work with (really).

This, at long last, brings me to the point of my story. Do you value the people you work with? Do you function well as a team? Do you help each other out? Do you offer to help when someone looks stressed or overwhelmed?

These may seem like minor considerations, but let’s face it: businesses can succeed or fail based on personal relationships alone. What has this got to do with tree health? Well, I’m good at what I do (and help you be good at what you do) because of all the people around me. Oh, and the third office chair from across the street? It was “just right.” Thanks, team.

Predicting Plant Health Issues in 2010
Every year, people ask me what my predictions are for plant pests this year. After I suppress a fleeting impulse to say “I’ve no idea,” I dig a bit deeper and come up with a few educated guesses based on my experience and the observations you share with me, yes you. Ontario arborists and landscapers are a wonderful group of plant lovers who manage to take the time to share their plant health experiences and observations with me.

Every 4-7 years or so, we see outbreaks of various leaf-feeding caterpillars. Last year, we saw cankerworm larval populations really starting to build in southwestern Ontario. Cankerworms consume foliage of deciduous trees (e.g. Tilia, Quercus, Corylus), leaving only the main leaf veins behind in spring. Look for greenish to grey inchworms feeding from leaf edges or undersides. Note they can really camouflage themselves with their colouring.

In Ontario we have two species: spring cankerworm (Paleacrata vernata) and fall cankerworm (Alsophila pometaria). The name refers to the time of year the adults mate and lay their eggs, however eggs of both species hatch in the spring. Spring cankerworms have two pairs of prolegs (fleshy pods used as legs) at the end of their abdomen. Fall cankerworms have three pairs of prolegs. Larvae are marked with light green and dark longitudinal stripes which become more noticeable as they become bigger. They grow to lengths of about 1 inch. Young caterpillars are susceptible to the biological insecticide B.t. (Bacillus thuringiensis, e.g. DipelTM) when it is applied as a foliar spray. Note that B.t. is an exempt pesticide under the Ontario cosmetic pesticide ban. Cankerworms have one generation per year, so trees will be able to re-foliate in June.

Aphids & Leafhoppers
These two were an absolute nightmare last year. A lot of this had to do with the slow leaf emergence period because of the cool, wet weather. Not surprisingly, we’ve experienced the total opposite in 2010 so far. Leaf emergence has been exceedingly rushed and several species have already completely flushed out. Once leaves reach their full size and harden off (produce a tough, waxy cuticle), they are much less desirable for sucking insect pests to feed on. The result is a more moderate crop of aphids and damage, I hope.

European Pine Sawfly
These guys were also a big problem last year, so much so they even made our local TV news. Larvae hatched during the first week of May (or earlier) this year. Examine last year’s foliage closely for dark green, longitudinally striped larvae laying along the length of needles in groups. When they are small, they are extremely sensitive to even the lowest toxic pesticides. Some horticulturalists will remove them manually since they feed in groups for the first couple of weeks.

As they get larger, effective pesticide products must be stronger to compensate. Spinosad (e.g. SuccessTM) is a great, lower toxicity choice to manage sawflies on trees. Success is not exempt from the Ontario cosmetic pesticide ban. Note that tree care specialists have to fulfill additional requirements to make applications of non-exempt pesticides. B.t. is NOT effective on sawfly larvae.

Leaf Diseases
We will probably get a break from leaf diseases this year given how warm and dry it has been. As stated earlier, leaf emergence and hardening off has been accelerated and we are well under average rainfall for this time of year in much of southern Ontario. Without those leaf wetness periods and long periods of soft, succulent leaf tissue, pathogens will be a lot less successful at infecting and colonizing our beloved plants.
If you are seeing blackened, shriveled buds and partially expanded leaf tissue this month, don’t assume it is a disease problem right away. Unusually early leaf emergence left tender buds and foliage exposed to negative temperatures for several nights in late April and early May. Sometimes it can take several days for low temperature injury to become evident and we can be tricked into thinking we are dealing with a disease issue as the primary cause of the symptoms. Most frost-killed plants will recover quite nicely from this type of injury. However, damaged flower buds and flowers will not recover and you will have to wait until next year for the next crop of flowers and fruit.

Contact Information

This column is written by Jen Llewellyn, Ontario Ministry of Agriculture and Food and Rural Affairs (OMAFRA) Nursery Crops Specialist

Email any questions you have directly to Jen and we'll publish her response.

P: 519-824-4120 ext. 52671 • F: 519-767-0755

OMAF website:

Nursery Landscape Agriphone: 1-888-290-4441

Our mission is to enhance and promote the care and benefit of trees for present and future generations in Ontario through education, research and awareness.