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A War on weeds

Got a dandelion or thistle infestation this spring? A new guide could help with eradication of the pesky plants

They're the bane of gardens everywhere, but perhaps nowhere more so than in the Pacific Northwest. With our typically mild winters and warm, wet springs, weeds make themselves at home in exactly the spots we don't want them: flower beds, lawns - even sprouting up through cracks in our sidewalks.

It's every gardener's dream to figure out a safe and effective way to get rid of weeds, those herbaceous plants that grow where we least want them to.

And it's every gardener's nightmare when they return, unbidden and perennially, to the lovingly tilled soil.

There are weeds that masquerade as flowers (dandelions) and weeds that prick un-gloved fingers (thistles).

There are weeds that are fairly easy to pull from the ground (spreading sticky weeds) and weeds that need to be dug out with a hoe (the aforementioned dandelions, officially known as Taraxacum Officinale, for example).

Most gardeners detest them - unless they go for the whimsical by plucking the stem of a seed head and blowing off the fluff to make a wish - but the more you try to weed them up, the faster they grow. The taproot of a dandelion is deep, twisted, and brittle. Unless you remove it completely, it will regenerate. If you break off more pieces than you unearth, the dandelion wins.

This time of year in Oregon, you can easily spend an entire weekend afternoon wrestling weeds from flower beds. Even areas of your garden covered with bark dust aren't immune to the pesky plants.

Some folks use natural methods, such as vinegar and boiling water, to drown and kill weeds, while others go right for the chemicals. Some of the best known are Monsanto's Roundup, a systemic, broad spectrum herbicide that contains glyphosate, and Ortho's Weed-B-Gon Max, advertised to nix more than 200 types of weeds, including clover and crabgrass, while leaving your lawn lush and green.

With names like Sowthistle, Beggarwood, Devil's Shoestring and Cancer-root, it's no wonder we want to get rid of weeds. There aren't enough hand-held tools in all the garden centers in Oregon to take care of the abundance that invades a homeowner's space each year.

New guides available

But help is on its way. The Oregon State University Extension Service has come out with three new research-based guides - each with its own website - on how to manage weeds, insects and plant disease. Revised for 2012, the handbooks provide extensive information on chemical and non-chemical control methods in the ongoing battle against garden encroachers.

The weed management guide is available in print and may be purchased for $50 online or by calling OSU Extension and Experiment Station Communications office at 1-800-561-6719. The weed guide, a quick reference to weed control practices in Oregon, Idaho and Washington, is updated quarterly.

With 562 pages, the handbook is a comprehensive guide to weed management in the Pacific Northwest. It covers biological weed control agents, pesticide safety and disposal, agrichemicals and their properties and control of problem weeds.

The guide also contains sections on weed control in cereal grain crops; grass seed crops; forage and seed crops; legumes; oilseed crops; irrigated field crops; aquatics; forestry; orchards and vineyards; small fruits; vegetable crops; vegetable seed crops; Christmas trees; nursery, greenhouse and bulb crops; professional landscape maintenance; turfgrass; home landscapes and gardens; pasture and rangeland; and non-cropland and right-of-way.

In each section, products are listed along with application rates, timing, and other remarks. And the book includes a glossary, conversion tables, chemical application calculations, and a full index.

Chemical regulation of plant growth is complex, and a large portion of the handbook is devoted to registered uses of herbicides, crop desiccants and plant growth regulators. Recommendations in the guide are based on research by biologists at the experiment stations and extension services in the tri-state area.