Tuesday, June 10, 2014

Kill crab grass, goat heads, and star thistle

Crab grass didn’t used to grow in Grants Pass when I lived here in the 80’s.  Neither did goat head, known locally as puncture vine for what it does to bike tires.  Star thistle was out in the country on neglected farms.  Now we have all three all over town, the last two mostly on business, government, and vacant lots; people mostly don’t tolerate them around residences.

          All three can be hard to pull, but are easy to kill with a good pair of gardening scissors.  Kengyu pruning scissors are the best.  They are super-hard Japanese steel.  They can cut through dirt and gravel and still cut branches; they slowly wear down, but they don’t knick.  They may lie outside and get surface rust, but it wears right off with use.  They can not only cut weeds out of gravel; they can cut weed crowns out of cracks in pavement.  They can be found online.
          Any annual weed can be killed by cutting it off under the crown when it is blooming.  You don’t have to get the root; it has no food in it at that point.  Once it flowers, it has put all of its energy into its crown and above.

Green crab grass with dry foxtails and cheat

Young crab grass, spreading variety.  Some stand tall.

          Crab grass (Digitaria) likes water, but it can live on dust and dew.  It is related to Bermuda grass (Cynodon dactylon), with the same fingered seed head, but no underground rhizomes.  Where it has not been watered well, it has just enough root to hold it in the ground and pulls easily.  Where it has had good water, it roots deep and hard, and roots along stem nodes as well, the opposite of most annual grasses, but crab grass acts more like a tender perennial, and doesn’t die until frost.  Its roots are thin, tough and wiry, and don’t pull when mature and rooted deep.  Cut them off though, and the plant is gone; they have no food storage.

Goathead leaves and bloom 

Goat heads in bloom

          Goat head, Terrestris tribulus, literally “ground trouble,” crawls along the ground in a spreading mat with inch-long divided leaves and ¼” five-petal yellow flowers that open with full sunlight.  It laughs at mowers, spreading its tack-shaped seeds on their tires.  Also called tack vine, puncture vine, caltrops, and other names not suitable for print, its seeds can puncture bike, wheelbarrow, and some trailer tires.   It grows well in wet or dry ground, in bare soil or thick grass, spreading up to 3 feet across.  But its crown can be cut off its root, and the root will die.

            Yellow star thistle, Centaurea solstitialis, can be seen taking over vacant lots around the newer parts of town, its bluish foliage standing out among the drying grasses.  Its spines are only on its flower buds and fold down when they go to seed, but they are enough to declare it a noxious weed.  It doesn’t spread its seed on the breeze like other thistles, but on animals, lawn mowers and landscape maintenance workers; they cling to the plant all through the winter, long after the spines are gone.  It loves dry ground, but contrary to rumor, it can take heavy watering and come up through considerable mulch.  Mowing just makes it eventually seed out beneath the blades.  But its crown is often several inches above the soil bent sideways, handy for cutting off its root.

Cool off and Make Rain with Misters

Our snowpack is low but Lost Creek reservoir is full and Applegate is at 90% of capacity.  Nonetheless, Josephine County has been declared to be in a drought emergency, though the Rogue River, from which Grants Pass gets its water, is unaffected because our reservoir is full.  The hot, dry heat of a Southern Oregon summer will soon be upon us, and if we don’t get rain with our thunder and lightning, we will have forest fires and fish could be dying in the Applegate by fall.
So those of us who take our water from the Rogue should use it to keep our plants green and make rain.  It’s not like we could save it and send it to the people who are in the drought areas.  The only way we can share our water is by using it for irrigation, helping the water cycle to make rain by throwing it in the air, on the plants and the ground, and sending water vapor uphill and upstream on the prevailing wind to condense in the top of our water shed, or right on our heads when thunderstorm conditions are upon us.  Drip cannot do this, wash dust off your plants, nor water your plants half as well as sprinklers.
But one should use sprinklers only as much as necessary to keep one’s yard watered:  deeply and weekly.  It wouldn’t do to keep it running all day every day, though some did just that to keep the smoke at bay last summer.  But that gets expensive, breeds crane flies that eat grass roots, and makes a swamp that can be hard on plants.
Misters, however, can be run all day, every day and even all night, adding water directly to the air without greatly wetting the ground.  In our hot dry summers, plants, animals and people breathe easier with a little added coolness and humidity.  When smoke was choking us last summer, misters made a big difference in breathability, grabbing the smoke and taking it to the ground.  I could smell and feel the difference when I got home.
You can set up a mister system to air condition your yard with $10 misters that are often in stock at Diamond, the Grange, and Grovers; cheap ½” garden hoses; ½” male and female hose repairs; and hose Y’s, running them in a line around your front and back yards.  You want a hose running along with Y’s in it, and 15-20 foot hose lengths running to each mister from the Y’s.  1/2” hose is best because it has a smaller cross section than 5/8” but is the same strength of hose, so it doesn’t blow up and sometimes blow out under the pressure needed for misting.
Blueberries, which like their roots cool but their heads in full sun, do particularly well under the influence of mist.  Spider mites, which like dry and hot, do not love mist, so it’s good to use one in your greenhouse as well.