The Weekly Weeder -- Wild lettuce: Ugliest Weed Ever

          Prickly lettuce is one of the ugliest weeds ever when blooming, and it has started to bloom all over town.  As it bolts, its leaves stick out at unnatural angles, edges vertical, showing off its sharp points.  It grows 3-7 feet tall and spreads out at the top into wide, branching panicle of tiny yellow flowers that soon turn to small, fluffy seeds that fly on the wind to other properties.  It grows all over town, particularly on the neglected edges outside fences, and in cracks in the pavements.  It gets its name from the prickles on the base of its stem which pierce the bare hand that tries to pull it.  It screams seediness and neglect.

Young prickly lettuce

This looks like a domestic-wild hybrid of prickly lettuce

          There are many varieties of wild lettuce.  They all have a few traits in common, starting with being a composite flower (many tiny flowers in a each bloom, often with yellow strap petal flowers around the edges of the bloom, but some have all strap petal flowers and others have no petals) with seeds that fly on the wind, much like their short perennial relative, dandelion.  Unlike dandelion, the flowers grow on branching stems that can vary from a few inches to 18” tall in the case of groundsel in the spring, to 6 feet or more in summer with prickly lettuce and cow thistle, which looks much like a thistle with lettuce flowers but is not as spiny as true thistles.  Some wild lettuce mixes with domestic lettuce, creating interesting red shades.

"Soft" wild lettuce

False dandelion, which has been blooming knee-high in yards with dandelion-size flowers, is a wild lettuce.  This year, we have a new tiny, fine variety, half the regular size with half-inch yellow flowers, which has spread widely in the area and pulls rather easily.  We also have a soft, tall-growing variety with very dandelion-like leaves, with long, vertical branches on the stems that easily bend and buckle because the stems are soft and hollow.  Look up wild lettuce varieties on the internet, and you’ll see several more that grow in our woods, at least one of which is actually pretty, but still spreads like a weed.

          Unlike dandelion, they have tap roots usually only a few inches long that do not grow if cut an inch below the top of the root crown, being mostly annual weeds, though false dandelion is perennial and still dies.  They often pull out of the ground easily, but can be cut out if they break off above the crown. 

          If you weed them out of your yard and they keep appearing, there is an infestation within a half-block.  Wind-blown seeds don’t usually fly very far in a city full of trees.

          Also unlike dandelion, these weeds need no summer water to sprout and grow and tend to invade dry lawns, vacant lots, and cracks in pavements.  But they will sprout throughout the year with water as well.  What they need is bare soil or fine-textured mulch to get a touch of sun and hold the water needed to germinate their seeds. 

Whole-leaf mulch dries out on top quickly.  It deprives lettuce seeds in the soil of that touch of sun and those that fall on top of the leaves of the fine-textured seed bed that holds the moisture needed to sprout and grow.  A few layers of soft leaves will stop spring weeds like groundsel before they are eaten by soil life.  A couple inches of harder leaves will stop most weed seeds, and soften the soil to pull the ones that grow, while encouraging big-seeded perennial grasses to take over.  Bigger-seeded annual grasses will also grow through the leaves and need to be weeded out.  They are a softer, lighter green than the perennial grasses; see “cheat” and “foxtails.”

                               

Rycke Brown, Natural Gardener          541-955-9040        rycke@gardener.com

The Weekly Weeder: How to kill Star Thistle

          Star thistle is starting to bloom all over our town.  When I lived in Grants Pass in the ‘80s, I knew it only by reputation as a noxious weed.  It was way out in the county on neglected farms, of which there were few.  When I came back in 1999, it had taken over a field at Parkside School.   Now it is on all over vacant lots and neglected portions of business properties around town.  More and more of it grows on residential properties, particularly outside of fences and along streets. 

Cut but still flowering and gathering litter

          Star thistle is a gray-green plant with a distinctive growth habit, about a foot to 18 inches tall that has no spines except on the outside of its flower buds, but those are wicked.  When the yellow, ½ inch puffy flowers go to seed, the very sharp spines fold down around the stems and are no longer dangerous, but as long as they are blooming, they are spiny.  Mowing shortens the plant, but it continues to bloom and make seed under the mower blades if cut above the bottom branches.  The seeds do not fly on the wind, but stick to fur, clothing and mowers with their fluff and thereby spread through the winter.

Growing along a sidewalk on Agnes and N Street, railroad property

          It has very tough stems and roots and does not pull easily, even from wet ground.  It loves dry ground but also germinates and grows in watered ground, despite rumors to the contrary.  But it can easily be killed by cutting under the crown from which the initial rosette of leaves grow, and later, under the branches of flowers after the leaves die off as it flowers.  It will not branch again on the bare stem below the branches. 

          There are biological controls.  The most effective are probably goats, which eat it even when it is showing its spines.  There are also two weevils and two flies which attack the developing seeds, but they can achieve only about 50% control, and using other methods like cutting can interfere with the breeding of the control insects.

          Mowing and cutting works only if one cuts below the branching of the stems after the plant has started to bolt, or below the rosette of leaves before that.  But a sharp pair of scissors and sharp eyes are probably more efficient than using a weed whacker to beat them into submission, considering the toughness of the stems below the branches.

          Glyphosate spray (Roundup, etcetera) kills the plant but fertilizes the ground for broadleaf plants like star thistle and other weeds.  Replanting the ground afterwards with a broadleaf ground cover like clover can suck up that fertilizer and eventually stop star thistle seeds from germinating by covering the soil and out-competing it, particularly if weeded as well.

Tilling before the plants bloom and retilling after each rain can get rid of star thistle after several seasons.  If you don’t want these or other windblown seeds to invade the tilled ground, replant to a strong competitor like tall fescue grass and/or clover in the fall.

                               

Rycke Brown, Natural Gardener          541-955-9040        rycke@gardener.com

The Weekly Weeder -- Fox tail and Cheat: Stickery fire hazards

Ripening fox tails

          Cheat and foxtails are drying out and dropping seed, but you can still reduce the number of seeds of these annual grasses infesting your landscape with quick action.  Both of these grasses have seeds that stick into socks and animal fur with barbs that make them hard to pull out the way they went in.  If nothing else, you should cut them and rake up as many seeds as you can, because they are a great fire hazard.

Fox tails dropping seeds into permeable pavement 

        Foxtails are well-known as a hazard to animals with fur, standing up straight up to about 12-15 inches with their tight brush of seeds at the top that fall off the stalk in joined pairs.  They not only stick into fur and socks; they get tracked into the house from the lawn, sticking in carpet. 

Mowed fox tails in Bermuda grass

Mowed foxtails keep growing until they seed out under the mower blades, with at least a dozen seeds per head, about half the size of unmowed foxtail seeds, an unsightly nuisance as they turn blond against the green lawn.  They stick hard into the ground with tough roots even after they dry, but can more easily be pulled out of damp ground, another good reason to water your yard.

Dry "nodding" cheat, a fire hazard next to the sidewalk

Cheat is less obvious, and many people don’t realize the source of the inch-long stickers in their socks or their pet: a tall grass, with a very loose seed head.  There are two varieties of cheat: a tall blond one with the thick stalk that stands a good three feet tall, very straight, that leaves empty shells hanging on the stalk after dropping its seeds, and a shorter, brown “nodding” variety on thin stalks that bend nearly to the ground under the weight of its very sharp seeds, hard to see against the background of other plants, and not leaving any hanging shells when the seeds fall off. 

Mass of tall dry cheat, Westholm Park

The former is the bigger fire hazard; the latter is most likely to grow in forest and to end up in your socks.  Cheat pulls relatively easily once it has begun to bloom, its one saving grace.   When mowed or in very poor soil, it can set as little as a single seed per stalk, keeping its numbers steady.

Green nodding cheat, in dry bitter cress

Foxtails and cheat start growing in fall.  The seeds are large enough to grow through several inches of mulch, but once they sprout, they can be smothered with 2” or more of compost or leaves.  They can also be easily pulled when very young.  Their color is lighter than perennial grasses.  They start blooming in April, showing which kind of grass they are, and should be pulled at that point, before they set seed and dry out.  They pull more easily when blooming than just before it.

A single dry nodding cheat

Weed control is seed control, and our city nuisance code tells up exactly when a weed becomes a nuisance: it forbids allowing weeds to mature or set seed.  Cutting these weeds before they ripen seed can reduce their seed numbers, a lot in the case of cheat; less so with foxtails, but you have to cut them repeatedly until they dry out.  Pulling plants before they drop seed is the better seed control.  It can be done more quickly than you might think. 

But if you have a lot of fox tail or cheat, your best bet may be to cut them; rake up as much as you can, and mulch them over in the fall after they sprout with 2” or more of leaves or compost, pulling any that come up through the mulch later, and plant good perennial grass in the spring, reseeding again in the fall.  It is easy to tell the annual grass from perennial by the light color and wider leaves of the annuals. Be sure to pull them young and later any that show their seed heads.