Golden Gate Gardener

A Weed to Watch Out For

My Golden Gate Gardening column in today's SF Chronicle (www.sfgate.com) was about Nothoscordum gracile, a weed to watch out for in your garden. I thought I would put a few photos in this post, for those who wonder if they have it and to help you understand what is going on underground if you do have it. The plant, shown at left, has white flowers that look a little like a brodiaea. It blooms most actively in summer. The leaves are strap-like, gray green, and do not have a midrib. This plant is not edible and does not have any scent of onion or garlic. The plants can be easily overlooked, but the best way to control them is to remove the first one you see, digging carefully to get all of the root and the bulblets, even discarding a handful of soil to be sure you got rid of all the bulblets.

Here is a mature bulb with its many bulblets, each the size of a grain of rice. The youngest ones are white, so they stand out well against the soil, but the older ones turn brown, and are very difficult to see. The bulbs are usually very deep in the soil--as deep as your shovel can reach. Be sure your shovel blade is straight up and down when it enters the soil, or you may cut the stem of the plant, leaving the bulb unmolested in the soil.

The problem with leaving some of the bulblets in the soil is that they will all germinate into small plants. Incompletely digging a Nothoscordum bulb, and then turning the soil in the bed can spread the bulblets all over, so that soon you will practically have a lawn of the plants. I am combating this weed now in a vegetable garden, digging out mature bulbs and also digging the smaller plants carefully to be sure I have removed the attached bulbs, and am ruing the day I tolerated the first plant of it. Don't make the same mistake.

The other weeds: Wildland Weeds

Some weeds escape mainly in gardens. Others may be weeds in gardens, or may not, but are able to grow in undisturbed, or relatively undisturbed wild habitats. A prime example is Algerian Ivy, which can cover the ground under redwood trees and climb them, sometimes causing them to die. Most plants not native to the redwood forest woudn't be able to grow there, but this one, from North Africa and the nearby Canary Islands, just takes over.

As the information about these pest plants gets out, gardeners who want to do the right thing begin to check whether a plant could be a wildland invasive before they plant it. This is a good thing, but going online to check can be tricky. If a search for the plant's name with the word "invasive" or "wildland weed" turns up a lot of hits, you still may not be clear whether the plant is invasive where you live.

In California, the best site to check for this information is the California Invasive Plant Council. Here is a link to their site:

www.cal-ipc.org California Invasive Plant Council. This nonprofit seeks to reduce the escape of non-native invasive plants into California’s wildlands. The entire book Invasive Plants of California’s Wildlands, with both text and photos, is available on their site.

If what you want to do is find out where wildland weeds are being combatted near you, with the thought you might volunteer to help, this next link is for you:

http://www.ice.ucdavis.edu/nrpi/  This is the Natural Resource Project Inventory. If you scroll down and click on "county" and then select your county and click on "submit" you will find out where the nearby action is. These projects welcome volunteers and can be fun and a good place to make new friends.

I've been weeding a lot lately

This is the season when our gardens often look like the weeds are winning. In our mediterranean climate, winter rains bring weeds, many of them natives of The Mediterranean (the European or African lands that border the Mediterranean sea) so they are used to this winter rain-enabled life cycle.

While it is tempting to think of weeds en masse, there are a number of reasons to identify them. The skillful gardener notices new weeds and learns how to fight them before they get a root-hold, and knows which of the usual cast of weed characters have underground structures (like bulbs or running roots) that must be removed if one is to get rid of them.

Identifying weeds can be difficult, but if you can get as far as common name, you can learn quite a bit about your weeds on the following two web sites designed for California gardeners. And, knowledge, as they say, is power.

http://www.cdfa.ca.gov/phpps/ipc/encycloweedia/encycloweedia_hp.htm

Find weeds by common or scientific names, read about them or see photos. Look at the national weed list & at the California weed list. Check out the pdf of the Noxious Times, the California Dept. of Food and Agriculture weed management newsletter.

http://www.ipm.ucdavis.edu/PMG/weeds_common.html

This site offers a weed photo gallery that is searchable by common name. From here you can also go to the same weed list searchable by scientific name or by plant family name. You can also read about weeds that cause problems in turf.

Oxalis Attacks Bay Area

I've been getting a number of letters about Cape oxalis (Oxalis pes-caprae), a weed that is now in full bloom in San Francisco. Also known as Bermuda buttercup, this South African native wildflower is has pretty yellow flowers that are cheery to see blooming on weedy road verges, but in a garden, it is a terrible pest. It grows in fall, blooms about now, and then dies back in later spring.

Cape oxalis grows from small tear-drop shaped bulbs that are dormant in summer, so many an unsuspecting gardener has planted in summer without realizing it was there. When it does appear, some think it is a clover, since it has trefoil leaves like a clover, and hope it will add nitrogen to soil. It won't. I have written my February 21st S.F. Chronicle column on this weed and how to (attempt to) get rid of it, so check out sfgate.com on that day.

Oxalis gets its sour flavor from oxalic acid, a substance that is also found in French sorrel, and, to a lesser extent in chard, beet greens, and spinach. We shouldn't eat great quantities of a plant that contains as much oxalic acid as Oxalis, but it is a nice nibble or could be added to salad in small amounts. In fact, I just read an article by a Greek writer about using Cape oxalis with French sorrel and other wild greens in soup or savory pie. I shall try to get recipes!

Less Toxic Herbicides?

I have often been asked whether vinegar was a good weed killer. I have thought it had potential, but it has been my understanding that the weak vinegar solution we use in cooking is probably not strong enough to work well. Now, recently, I have been sent a sample of a weedkiller, containing 8% clove oil, 90% vinegar, and 2% lecithin. It is called Perfectly Natural Weed and Grass Killer. I have been using it on the weeds in the sidewalk cracks in front of my house. It has worked well on annuals, and has killed some of the perennials, like dandelions, but a couple of those have recovered. I tried it on them again today, a third time, ever hopeful.

The vinegar in Perfectly Natural Weed and Grass Killer is 8% acetic acid, quite a bit stronger than ordinary vinegar, and, no doubt, harmful even to get on ones skin in that concentration. The lecithin is a food product used to emulsify, that is, mix oil and water, so it probably just keeps the clove oil in suspension. Interestingly, the clove oil is listed as the active ingredient, the vinegar as an inert, or inactive ingredient, though I'm sure it has an herbicidal effect.

My web research tells me that this is a Canadian product, and that Home Depot will be carrying it in the U.S..  A Colma Home Depot worker tells me they don't have it or know about it, but that they have had several queries about it this week.

A similar product mentioned on the web is Burnout II, which is 4% clove oil, and also contains vinegar, citric acid, lecithin, sodium laurel sulphate, and mineral oil.

A study that compared several herbicides, including the herbicide Roundup (which contains the synthetic compound glyphosate) and Burnout II, found that these two products produced similar results, however while the Roundup cost $80 an acre, the Burnout II cost $1200 an acre. This is dramatic. Though I didn't buy my Perfectly Natural Weed and Grass Killer, I supect the price of it is similar to Burnout II, however, since I am using it only on weeds in cracks where I can't pull them, I won't need much of it to do the trick.

In summary, either of these vinegar and clove oil based herbicides are reasonably effective unselective herbicides and, unlike Roundup. they don't introduce synthetic chemicals into the environment. If I can figure out where to buy more of this kind of herbicide, I will do so.