Lowenfels: Time is critical for addressing Alaska's invasive weeds

GardeningJuly 24, 2013 

Canada thistle (Cirsium arvense): Dropped or windblown seeds can remain dormant in the soil for 20 years or more. The plant’s creeping roots – above and below ground – also regenerate multiple shoots from small fragments.

PHOTO COURTESY COOPERATIVE EXTENSION SERVICE

The other day I while walking in the Sky Hills subdivision, I came upon several stands of orange hawkweed, a noxious and invasive weed with lovely redish/orange dandelion-like flowers with just as many seeds. I've seen it there in years past and have even knocked on the door of one homeowner to tell her about its presence. Heck, a couple of years ago, I walked the neighborhood with the nice folks who ran its association and pointed out not only hawkweed, but reed canary grass, Canada thistle, rampion campanulas and a few other invasive that now slip my mind.

That was then and this is now and they are everywhere throughout the subdivision, no doubt. They are not called invasive for nothing. They are true to their grouping and make rapid and extensive inroads in just a few years. Pretty soon, it isn't just dandelions driving you crazy, but dense-so-nothing-else-grows expanses of unwanted weeds with no hope of control.

The only real defense between you and this scenario, i.e. a whole host of invasive plants floating into your neighborhood, is you and your neighbors. And, I can promise you that if action isn't taken, dandelions will look like nothing when it comes to enemies in weed warfare.

The first thing you must do is familiarize yourself with the weeds you really, really don't want in your yard. This is an easy task thanks to the internet. Start by pointing a web browser to www.uaf.edu/ces/pests/cnipm/plants/ and there they are, from A to Z -- actually from black bindweed to yellow toadflax. Spend the time to check out what these weeds look like.

Lots of us have Tatarian honeysuckle (Lonicera tatarica) in our yards. In fact, these are some of the older shrubs in town, planted before biologists could determine they spread. Many have also had a nasty bout with rampion bellflower (Campanula rapunculoides) picked up at a garage sale or given as a gift by a well-meaning neighbor.

What to do about these existing trees and shrubs is a tough decision. Ultimately, they have to go and surely, new ones should not be planted. The herbaceous weeds, however, are another thing altogether. They do need to go and go right now. It is important that we pay attention to their presence and try, whenever possible, to eradicate them before they get a foothold.

Some of these will grow so thick that they will take over the banks of rivers and streams to the detriment of fishing. No one wants that to happen. Others, like garlic mustard in particular, will kill off the mycorrhizal fungi that support trees, preventing their growth. This is exactly what is happening to the maple trees in Michigan. Its not the fisherman leaving worms, it's the garlic mustard that grows in after the worms do their thing. They kill the mycorrhizal fungi that feed maple trees and prevent new maples from growing.

Other weeds come in via automobiles and trucks as stowaways in treads and bumpers and such and obliterate everything that grows along roadsides. Then they start to invade the surrounding forests and yards. In some instances, invasive were used to prevent erosion during construction, I guess. No matter, they are a pest and they will get worse and worse as they spread.

So, examine the list and get to know the plants. (There are booklets with the information as well, often found at nurseries for free). Be vigilant. When you are out and walking about, take a bag with you to collect seed heads and flowers from patches you encounter. And if you need to knock on a few doors to let folks know what they have growing in their yards, do it. This becomes even more important the closer you get to your own yard.

Jeff Lowenfels' best-selling books can be ordered at tinyurl.com/TeamingWithMicrobes and tinyurl.com/TeamingWithNutrients.

Garden calendar

WATER: AS NEEDED.

RASPBERRIES: ARE YOURS RIPE? KEEP AN EYE ON THEM. THE BEARS ARE.

GARLIC: NOW IS THE TIME TO ORDER GARLIC FROM OUTSIDE CATALOGS (TRY TERRITORIALSEED.COM AND WWW.NICHOLSGARDENNURSERY.COM/STORE. IT IS ALSO TIME TO HARVEST YOURS, OR AT LEAST CHECK TO SEE IF IT IS READY.

THIN: THINGS ARE GROWING FAST. CARROTS, BEETS, LETTUCE, KALE, ETC. NEED TO BE THINNED SO THE PLANTS CAN CONTINUE TO GROW BIGGER UNIMPEDED.

 

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