Around the Garden

“Be Careful What You Spray For…”

Lost in the hoo-ha about honeybees and colony collapse disorder is the story of our native pollinators. Desirable though honeybees are, they aren’t really native – not that that is a bad thing, mind you.

But it is important to remember that a lot of pollination – and thus, the production of what we eat – comes from bumblebees, wasps, flies and even an occasional highly specialized bird.

Unfortunately, when the paddy-wagon comes, they take the good girls along with the bad, as my dear mother used to warn me. If you are suffering from whiplash brought on by this change of topic, let me just say that most insect sprays are not highly specialized.

Today, for example, a whole bunch of teensy wasps was cavorting inside a rugosa rose in my garden. So were a few Japanese beetles. I’m pretty sure those wasps were carrying pollen off on their abdomens. If I had sprayed the Japanese beetles, I probably wouldn’t have wasps any more either.

This one is easy, since there are other ways of killing Japanese beetles. They’re a bit sluggish, for one thing – you can flick them off a plant into a bucket of soapy water. Or, if I had planned ahead, I might have spread milky spore last fall to kill the grubs from which those Japanese beetles hatched.

But what about the tougher issues? I have a row of hemlock trees that buffer my neighbors from my ragged excuse for a lawn. Hemlocks have had a tough time lately: the Hemlock woolly adelgid has ravaged stands of hemlock from the Carolinas nearly to Canada. My trees, like many others, have been treated occasionally with Horticultural oil, a broad-spectrum insecticide that works by suffocating the insects on which it lands.

Recently, however, I lost a couple of small hemlocks, and then noticed signs of Spruce spider mites on the trees. Spider mites are devilish hard to control (the reasonable goal, since outright extermination is usually a bad thing.) They are tiny, fast-moving, and resistant to many insecticides, since they aren’t even insects, but arachnids.

There is a plausible theory that some insecticides escalate spider mite reproduction. Other experts think that the mechanism is merely opportunism: when one insect is eliminated, another pest leaps in to fill the niche. Whatever the case, now I have spider mites, so I have to decide whether to pursue them with stronger poison.

Some factors to consider when we find destructive insects are: how much damage can this plant sustain and how much do I value this plant? Is there a viable, safe treatment that will control

this pest? Is this the right time to apply the treatment? (High temperatures intensify some sprays, and might burn a plant’s leaves.) Would it make sense to wait and see, in case some other insect wants to eat whoever is eating my plant?

A great place to investigate the answers to these and other questions is on the web site of the CT Agricultural Experiment Station. Their Plant Pest Handbook is available online at http://www.ct.gov/caes/cwp/view.asp?a=2826&q=378182&caesNav=|.

Or – and this is really interesting – you can bag up your plant or insect sample and take it to Jenkins Laboratory at the Experiment Station in New Haven. Depending on what your plant’s problem is, a pathologist or an entomologist will provide a diagnosis, and you will see the critters in living color under high-powered microscopes. This is a free service, paid for with our tax dollars, at least for the time being. CAES was one of the targeted agencies under the Malloy “Plan B.”

Stay tuned.