DougGreensGarden

For a very long time now, organic gardeners have believed that plants have self-defense mechanisms that work against insects and diseases. A plant is attacked and it defends itself by releasing hormones or biochemicals.

This has been confirmed in multiple experiments now with regard to insects and now, thanks to the USDA, research on plant responses to fungal infections is also proven.

Scientists working with corn found the plants produced zealexins and kauralexins (volatile organic compounds) to fight back when attacked by fungus. Both of these products are derived from forms of Terpenes (another chemical) and scientists have been studying Terpenes for some time because they’re produced under insect attack.

So now we know plants have defense systems for both insect and fungal attacks.
In practical terms, this means if we keep our plants healthy, they’ll produce the basic products to fight off attacking insects and diseases. It’s only when we allow our plants to be stressed that we can expect the insects and diseases to win (in the average scenario)

So your job as a gardener is to reduce plant stress.

And herein lies the challenge of gardening – creating conditions plants love enough to grow strongly and stress free. Want to bet they’ll discover organic gardening does a better job of this than anything else?

Originally published in January 2012 issue of Agricultural Research

The almost invisible cyclamen mite is a common pest on greenhouse plants when it’s been a cool spring so you may be seeing a few problems that you can’t identify until the weather warms up considerably.
These mites hide in darker, damper areas of the plant (leaf axils etc) They actually inject a toxin into the plant as they feed so you’ll begin to see
While not restricting themselves, Cyclamen mites do prefer cyclamen, dahlia, gloxinia, ivy, snapdragons, vinca, chrysanthemum, geranium, fuchsia, begonia and petunia.
And they’ll eat mostly buds or young leaves. The leaves curl inward developing a puckered appearance. Leaves may become brittle or appear streaked. Flowers may shrivel up, be discolored or the buds may not open.
Broad mites prefer to feed on ageratum, begonia, cyclamen, dahlia, gerbera, gloxinia, hibiscus, ivy, jasmine, impatiens, New Guinea impatiens, lantana, marigold, snapdragon, verbena and zinnia as well as beans, peppers and tomatoes.
Broad mites feed on the underside of leaves and leaves twist and distort with bronzed lower surfaces and they frequently turn downwards. Younger buds can be killed.
You won’t see them unless you have a microscope – all you’ll see is the damage symptoms.
Get out the insecticidal soap and start following the label’s spray directions for continued coverage. And as I said, once the heat increases, damage should subside.