eGarden © 2004 Ed Mues

Going After Weed Enemies

I'm reporting today on the most favorable time to go after the non-legged but intrepid predators of our lands. In mid-July, I wrote about the attack of the aliens. Their number is many. They are claiming our valuable resources: land, wildlife, natural habitats, and maybe entire ecosystems. Our clean water is at stake as are our garden spaces and personal landscape areas.

I name some of the major weeds in our area. Not all are aliens, but many are. I'll use common names and comment on that, too, in just a bit. Bedstraw, bittercress, broadleaf and buckthorn plantain, burdock, common pigweed, crabgrass and several other weedy grasses, curled dock, dandelion, garlic mustard, ground ivy, Japanese knotweed, lambsquarters, multiflora rose, purslane, sheep sorrel, smartweed and yellow wood sorrel. These are the more common competitors for space, moisture, nutrients and sunlight that appear all around us.

Just this week I was out walking my dog, Dusty, and I noticed once again, six feet from the road's edge, a lovely flowering plant. Blue, bell-shaped flowers on fairly long, sturdy stems in the same place as last year. I decided it was time to act. Knowing it might be an alien, knowing it had spread and was clearly a successful survivor having weathered this past January's extreme cold, I also knew not to dig it up and plant it. Instead, I cut a stem and brought it home for identification. It is Creeping bellflower, an alien. Peterson's Field Guide to Wildflowers was my source. Not regarded as a weed at this time.

I decided to just leave it where it grows and I can enjoy it there. If you have a desire to rid your property of weeds, this is the first step. Do not transplant anything into your landscape until you know its origins and growth habit. The only sure way is to use a good guide or two for reference, and to continue to observe, once the candidate is positively identified.

The best guide (handbook) I have seen for identification of weeds in our area is the 1997 publication "Weeds of the Northeast". This book, used in conjunction with the Peterson guide mentioned above, will serve you well to positively know the enemy. Common names are useful, but can complicate identification, until the actual plant is known. That's where guides are valuable, because they also use the Latin botanical name (Scientific name) which will narrow a few with the same nickname, to the one true plant I.D. Another useful pocket guide is "A Golden Guide - Weeds", author Martin. About $3, but not as complete as the other two.

So, knowledge is the first step. We now should also know if the offending weed is an alien or native. We should know if it's an annual (crabgrass), biennial (burdock), or perennial (dandelion). The next step is to understand that weed seeds are already present in the ground from previous years. If you never allow any new weeds to flower and produce seeds, you are beginning to reduce the store of seeds that reach the ground.

Next we must remember weed seeds can be brought to the surface and germinate simply by our cultivating any soil. Weeds and bare soil go together like hands and gloves; one has an inner longing to fill the other. And, not without good reason. Weeds colonize bare ground and prevent erosion. Part of the 'yearning' must be from the soil.

It's part of nature's design. Instead, where you see bare ground, you can accomplish the same as Mother Nature and conserve valuable topsoil by simply mulching. There are several mulch choices. Clean, weed-seed free organic materials such as grass clippings, shredded bark, straw, pine needles, pebbles and compost will all serve to stem erosion and inhibit weed growth.

Additional barriers to weed growth may include newspaper, landscape fabric, black plastic and carpet. These last would be more for aisles and pathways, in my opinion.

There is still another mulch choice to consider. If the bare ground area is not to be planted this season, plant it anyhow, but with a cover crop that will grow densely, improve soil tilth and drainage, crowd out and shade out any weeds that try to get established, and, in all likelihood, eliminate the need for future cultivation. This proactive step is a major one. The crop is commonly called green manure. It might be annual rye, winter wheat, clover etc. This is a whole subject unto itself.

After the above steps to managing weed prevention, we move to the actual hands-on weed control. Some grunt work is coming up. Master Gardener Bea R. always told me how she used weeding as a meditation. I quickly became a convert. It works better than you can imagine. Here's the plan. Weed regularly and often. After a rain, is best. Juveniles come out of the ground with no effort. Biennials and perennials will require more effort, but with soft moist ground, and perhaps a tool, these, too, can come out with greater ease while still youths.

If it's a dandelion plant in your lawn, getting all of the root is key. Do not chop up the root as this will spread the pieces which will re-root. Annuals that are cut to the ground regularly can be left alone once they are dead or not re-sprouting. Their underground structure will further enrich the soil nutrition, and improve air and water drainage pathways. Perennials treated the same way will become weak, but will not be killed in a single season. Whenever you run up against a tuff competitor, stop, think, and wait. The answer is around the corner.

The next corner reveals much. Remembering that all plants are autotrophs, manufacturers of their own food, the above suggestion to continually cut them accomplishes two things: they will not flower and produce seeds; they will weaken day by day from starvation.

Imagine you have a massive stand of Japanese Knotweed. Regular mowing goes a long way to weakening it. If this isn't practical, there are other organic methods that can accomplish the same end. Flamers and flame throwers (best used during or right after rain or irrigation) kill the tops to the ground. A propane tank on a hand truck with a flamer attachment can do the trick.This does not disturb the soil at all. Of course, the mantra becomes repeat, repeat, repeat, if you do not wish to use chemicals.

If you are willing to bend a bit and use one annual dosage of Round-up or another broad spectrum herbicide containing glyphosate, the best time is at, or, just after, the blooming period of the target plant. So, if you've been cutting or flaming the Japanese Knotweed (or poison ivy, or, what have you), observe in your area when it begins to blossom. This is the signal that the plant will begin to take in as much of the herbicide as it can, unwittingly, to store in its roots (which is where we wish it to go) in preparation for winter.

Steaming, boiling water, rock salt, straight vinegar, and applying corn gluten meal against crabgrass and other annuals have all been recommended to the organic minded among us.

Still another method of killing the weed pests is solarization. I've mentioned this before in relation to killing harmful soil borne bacteria and diseases. It involves the simple cooking under plastic of the wet soil when the days are long and hot. The soil temps will skyrocket and anything inside will truly cook to death.

Only you can determine the practicality of using such a method. How big is your problem? Mow it short, wet it well, cover tightly with black plastic and the sun will do the rest. This probably won't work with Japanese knotweed, however. Other "organic" herbicides include the potassium salts of fatty acids found in herbicidal soaps. Also available are compounds derived from plants such as clove oil (eugenol) and 2-phenethly propionate (from peanuts).

Finally, if you wish to stay on the organic path, there is OMRI. The Organic Materials Review Institute lists many materials that can be used without jeopardizing your "organic" status.

Needless to say, there are an abundance of chemicals to control pre-and post-emergent weed pests. Some are selective, that is, they can be used to control a specific weed in a particular bed or area. Non-selective weed applications will, in general, kill almost all vegetation it comes in contact with, so care must be taken to protect your desired plants.

These chemical herbicides are the most likely candidates to endanger our environment, be it the air, the water, the microscopic beneficial soil flora and fauna. Caution should always be the watchword. Read labels carefully and completely, and follow direction precisely. There is more than one way to get rid of the unwanted weeds. I still like the meditation practice for the majority.

From The Garden of Ed. Submitted for publication in The Towne Crier on August 11, 2004

Page Up