Spring Gardening Special Section: Careful use of pesticides

Published on Thu, Apr 21, 2011 by Naomi Knowlton

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In my past two columns, I recommended three methods of removing noxious Morning Glory (bindweed) and Himalayan blackberry plants: manual (pulling or digging plants by hand), mechanical (mowing down plants for Himalayan blackberries and hand pulling for bindweed) and, as a last resort, herbicides.

As I had specific directions and recommendations for controlling each of these plants, you may want to refer to my previous columns for the details.

I also recommended using the herbicide glyphosate, but that information was edited out of my column. This is understandable because the use of herbicides is a complex and controversial topic. Let me clarify my stance on herbicides:

When using any herbicide it is imperative that you carefully read the label for specific warnings and follow the directions on how to apply the product, as well as ensuring that you are using the correct herbicide for your particular plant. Master Gardeners will only recommend the safest herbicide.

They will first encourage you to try biological controls, such as predatory insects and, failing that, manual and/or mechanical controls. Herbicides are recommended as a last resort.

The Washington State University Whatcom County Extension office in Bellingham can discuss with you the recommended herbicide for your particular application, or alternatively you can contact the Noxious Weed Control Program at 360/715-7470.
If you decide to use a herbicide on Morning Glory (bindweed), the WSU Master Gardeners recommend what they call “the glove of death.” As bindweed likes to climb, place a bamboo pole at the base of the vine. After it climbs up the pole, prepare your gloves—put on a pair of latex gloves, followed by a pair of washable cotton gloves.

Using glysophate (RoundUp is the most common brand name, although it’s no longer proprietary), dip your gloved hand into the herbicide and rub the leaves. No need to treat the stem, simply the leaves.

You can also use glysophate on the Himalayan blackberries by first manually cutting the cane down to within a couple inches of the ground and applying a few drops directly on the woody stem. Leave the plant in place for a couple of weeks until it dies completely. Glysophate, if used correctly, is considered one of the safest herbicides. It is not residual in the soil, and it travels through the vascular system to the roots of the plant to which it is applied.

We live in a fragile ecosystem, and directly on the Drayton Harbor watershed, so thoughtful use of herbicides is recommended. We can often eliminate the need for toxic chemicals if we create a healthy balance between pests and predators, diseases and biologically safe controls (i.e. pulling those young bindweeds or pruning and digging Himalayan blackberry plants). 

Send your gardening questions to me, the Garden‚ÄąGuru, at info@thenorthernlight.com.