Every gardener knows that weeds are just plants in the wrong place. Webster's dictionary defines a weed as “a plant that is not valued where it is growing and is usually of vigorous growth; especially: one that tends to overgrow or choke out more desirable plants.”

In nature, weeds play an important role. They can resist conditions like drought, acidic soil, lack of humus, and mineral deficiencies. Weeds protect our topsoil from eroding away in heavy rains and strong wind. They provide a cover and shade for soil microbes and insects.

Some weeds, those with large root systems or a taproot, penetrate deep into subsoil, breaking up compaction, which helps drainage and new growth. This deep penetration enables weeds to accumulate trace elements from the subsoil, and bring them to the soil's surface. The plants then die back and decompose, becoming what is called green manure.

Many years ago various weeds were used for food and pharmaceutical products. Currently, foraging for wild foods and mushrooms has made a comeback. Weeds in the legume family fix nitrogen in the soil and are often used as a cover crop to help enrich the soil over winter. Weeds have also been used to help indicate the presence of ground water. Curly dock is a weed that's typically found in wet saturated soils.

The primary value of weeds, wrote the eminent U.S. botanist Frederick Clements in 1920, is to “reveal information about the health and pH of our soils.” For example, certain species are confined to acidic soils and others to alkaline.

The use of weeds as soil indicators is not a new idea. Many early North American immigrants to the eastern United States chose land for their farms according to the weeds, plants, and trees that it supported. Conifers were characteristic of sandy, acidic soils that had little agricultural value. Birch, beech, maple, and hemlock indicated fertile soil. They learned that the tall-grass prairies were suitable for cereals, hay, and orchards. The bunch grass regions were better suited to wheat and grass.

If we look at our own gardens we can use our weeds to tell us what we can do to improve our soil. For instance, if our lawn is being taken over by clover we can note that clover thrives with low levels of nitrogen in the soil. We can remedy the problem by applying a nitrogen fertilizer (a 16-16-16 fertilizer is a good balance for turfgrass).

Another useful indicator comes from growing hydrangea, a beautiful and common flowering plant. If your soil is acidic the flowers will be blue. If your soil is more alkaline the flowers will be pink.

Ehrenfried E. Pfeiffer, a European scientist and student of Rudolf Steiner, wrote an entire book on this subject in the 1950's: “Weeds and What They Tell Us” (still in print). According to Pfeiffer, sorrel, plantain, horsetail, and knotweed are found in acidic soils. Dry soils with very little humus might support mustard, thistle, broom, and St. John's wort.

Sandy soils will have goldenrod, aster and toad flax. Alkaline soils support chicory, spotted spurge, sagebrush and woody aster. In heavy clay or compacted soil you might see morning glory, plantain, Bermuda grass, chickweed, and dandelion. Dandelions also indicate low calcium in the soil.

When you learn the type of soil some of these common weeds prefer you may be able to make corrections in the soil based on the information some weeds are giving you. If you really want to know, a soil analysis or at least a pH test by a local agricultural laboratory will provide factual information to accurately guide the use of soil amendments. Sometimes, improving drainage by adding well-balanced compost, organic manure, or employing cultural practices may be all that is required to improve your soil's tilth and nutrition.

Identifying the weeds in your garden can be fun! In some cases knowing what their presence indicates may help you manage your soil. Controlling weeds by hand weeding or with herbicide before they seed will reduce future populations if done consistently from year to year. One year's uncontrolled weeds can produce seven years seeds!  You may even develop a new appreciation for weeds.

For more information about weeds or help identifying them see:
UC Statewide Integrated Pest Management (IPM): Weeds
UC IMP Weed Photo Gallery
UC Weed Research & Information Center
Ehrenfried E. Pfeiffer, Weeds and What They Tell Us.

If you have a gardening question or problem, call the Master Gardener Hotline at (530) 538-7201 or email mgbutte@ucanr.edu.

The UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system, serving our community in a variety of ways, including 4H, farm advisors, and nutrition and physical activity programs.  Our mission is to enhance local quality of life by bringing practical, scientifically-based knowledge directly to our community. To learn more about UCCE Butte County Master Gardeners and their upcoming events, and for help with gardening in our area, visit https://ucanr.edu/sites/bcmg/.

Johnsongrass (Sorghum halepense) is a common sight throughout our hot dry Butte County summers.

It is also considered to be one of the world's most noxious perennial weeds. Johnsongrass forms dense showy bunches of vegetation three to six feet tall along pathways, in and around orchards and gardens, in open fields, and near waterways. In California, Johnsongrass is found in the Central Valley, Cascade Range foothills, Western California, and the Sierra Nevada foothills to about 2600 feet. Under certain conditions, its leaves produce a toxic acid which is poisonous to livestock.

This non-native weed arrived in Texas in the 1830s and by the late 19^th century was recognized as a problem in the North Valley and throughout California's agricultural fields.

Johnsongrass was even pointed to as a factor in the downfall of the world's largest vineyard at the time, Leland Stanford's 3,575 acres of grapes at Vina in Tehama County. When the vineyard closed in 1916, Prohibitionists argued that its demise was evidence that wine and brandy production could not be profitable in California, and therefore Prohibition would not adversely affect the state economy. But the business manager of the Stanford University Board of Trustees insisted that the vineyard had been profitable until Johnsongrass took over: “it was all through the vineyard. It became apparent that it could not be eliminated as long as the vines were left in place, and that, in order to get rid of the Johnson grass, it would be necessary to take the vines up and make a fight against it" (The Wine and Spirit Bulletin, v.30, 1916, p. 36). While the Stanford vineyard operation suffered other setbacks at the same time, Johnsongrass clearly served as a worthy scapegoat that farmers and gardeners could relate to.  (Stanford's ranch has currently been revitalized by the Cistercian Abbey of Our Lady of New Clairvaux in Vina.)

If you are a gardener contemplating a battle with Johnsongrass, know that it can be a relatively difficult fight if the weed has become well established, but that fight can be won. Digging the weed up is best done with younger, less established plants. You'll want the soil to be wet when you do this; the grass puts out networks of underground rhizomes which become long and brittle. Uprooting the grass in wet soil makes the brittle runners less likely to break away. When pieces of rhizomes break off and remain underground they will resprout. Mowing and tilling can be effective if repeated every two to four weeks. While these efforts might seem futile at first (you may despair when fresh growth appears from those underground runner fragments), over time repeated weeding and tilling will take a toll on the grass's energy reserves and you will gradually win the battle.

For more information on Johnsongrass biology and management see Biology and Management of Johnsongrass. Information on Stanford's vineyard operation is indebted to Stephen Maganini, “Wines, spirits, history, reflection blend at Vina Monastery Sacramento Bee, September 9, 2016.

The Butte County UC Master Gardeners are part of the University of California Cooperative Extension (UCCE) system, serving our community in a variety of ways, including 4H, farm advisors, and nutrition and physical activity programs.  Our mission is to enhance local quality of life by bringing practical, scientifically-based knowledge directly to our community. For more information on UCCE Butte County Master Gardeners and their upcoming events, and for help with gardening in our area, visit https://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-7201 or email mgbutte@ucanr.edu.

Puncturevine (Tribulus terrestris) is an attractive green plant with small yellow flowers commonly seen growing prostrate along the side of the road.

A native to Southern Europe, it's also referred to as “goathead.” However, underneath its foliage lies danger: spiky seedpods with needle-point spikes. If puncturevine is stepped on, it is painful to bare feet and dogs' paws; it will pierce and flatten bicycle tires. Because of its spiky seedpods puncturevine is also referred to as “caltrop,” after the spiked metal devices thrown on the roadway to stop vehicles. Caltrops have four projecting spikes with one spike always pointed up; just in the right position to puncture a tire or flip-flop, hence the similarity to puncturevine seedpods.

Puncturevine is a hardy summer annual that thrives in our hot, dry Mediterranean climate, even in areas of highly compacted soil. The plants are prostrate in sunny areas but can grow upright in shade. Their small yellow flowers tend to be open in mornings from April to October. A single plant can form a dense mat up to five feet in diameter, spreading outward from a center tap root. The spiky seedpods are hidden underneath the plant. Puncturevine plants are prolific; a single plant can produce 200 to 500 seeds during the growing season. And these seeds may be viable for up to five years, leading to increased spreading over time.

Puncturevine is listed as a “C-rated” noxious weed in California. This means it is widespread and a “known economic or environment detriment.” Besides being a danger to the public, it causes major problems along roadways and agricultural lands in several ways. Ingesting the hard spiky seedpods injures the mouths and digestive systems of livestock. The leaves contain compounds called saponins which are toxic, especially to sheep. And the puncturevine's deep taproot competes for water and nutrients in croplands.

Unfortunately, there are is no easy way to control this noxious weed. For most homeowners, the mechanical control methods of hand removal or cutting the plant off at the taproot are most effective. Any seeds left on the ground must be removed by raking or sweeping. Use heavy gloves to protect hands from the spiky seedpods. Of course, as with any weed, it's best to remove it before it flowers and sets seeds. This is especially important for puncturevine, as seeds are viable for years, and can be spread by shoes or the wheels of lawn mowers or carts.

If the plants are still small and have not produced seeds, shallow tilling (about one inch) is recommended for larger areas. Deep tilling is not recommended as any buried seeds are still viable, and can lead to future infestations. Mowing is usually not effective because the plants grow so close to the ground.

Biological control using several species of weevils have been tried but are not always effective. Chemical control of puncturevine in the home garden is often unnecessary. However, in heavily infested areas, or when hand removal is difficult, herbicide may be an option.

For more information on puncturevine see the IPM Pestnote No. 74128 and the IPM Weed Gallery.

The Butte County UC Master Gardeners are part of the University of California Cooperative Extension (UCCE) system, serving our community in a variety of ways, including 4H, farm advisors, and nutrition and physical activity programs.  Our mission is to enhance local quality of life by bringing practical, scientifically-based knowledge directly to our community. For more information on UCCE Butte County Master Gardeners and their upcoming events, and for help with gardening in our area, visit https://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-7201 or email mgbutte@ucanr.edu.

Why are wine bottles tall and narrow? That distinctive shape contributes to the happy marriage between cork and a bottle made tall enough to lie on its side so the wine can “breathe” through the cork as it matures. Lying on its side while stored in cool, dry cellars ensures that the liquid within the bottle will marinate the cork end just enough to keep it from drying out and crumbling.

That cork stopper sealing a delicious bottle of wine has been harvested from Quercus suber, an oak species whose bark contains high amounts of suberin, a waxy substance that is waterproof. Apparently the Latin word “suber” was derived from the Greek syphar,or “wrinkled skin.”

What do wine, wax, and wrinkles have to do with local trees? In 1904, a cork oak grove was planted in Lower Bidwell Park near the Nature Center on East 8th Street. The grove was located within a 29-acre tract of land that John Bidwell donated in 1888 to the newly created State Board of Forestry for use as a woody plant nursery and demonstration plantation.

Cuttings and young plants were collected from all over the globe for the project, including species of willow, mulberry, linden, maple, oak, catalpa, pine, and eucalyptus. The ensuing planting spree in the 1890s included Sequoia gigantica, a tract of Italian cypress (these trees gave rise to the name “Cedar” Grove), and a large plot of Scots pine. Of those late-19^th century conifer plantings, only the cypress remain: the Sequoia were decimated by a freak freeze in 1932, and bark beetles took all but a few of the pines.

The cork oaks, too, have survived. Quercus suber is a medium-sized evergreen tree with gnarled and wrinkled bark. Endemic to northwest Africa and Southwest Europe, it thrives in Mediterranean climates. Fossil remnants of cork oaks dating back to the Tertiary period have been found in the Mediterranean basin. The cork oak prefers acidic soils, and can be found in open woodlands and on hills and lower slopes at altitudes of 1,000 to 3,200 feet, especially in Portugal and Spain.

The species can reach about 66 feet in height, but is usually smaller than that in its native habitat. There are two notable exceptions: In Portugal, the Sobreiro Monumental (Monumental Cork Oak), is 234 years old and 52 feet tall, with a trunk so large in circumference that it takes up to five people with outstretched arms to encircle it. It is listed as a National Monument, and cited in the Guinness Book of Records as the largest and oldest cork oak in the world. Closer to home, a Quercus suber in Napa is registered as a California Big Tree. It is 89 feet tall, with a trunk circumference of 20 feet, and a crown spread of 81 feet.

The acorns of the cork oak have a distinctive fringed cap, smooth chestnut skin, and characteristic green mark at the bottom, and the tree's shiny, deep green, loosely-lobed leaves are attractive. But its bark is the cork oak's claim to fame. Almost ghostly pale in color, the bark is deeply furrowed and springy, and provides an ecologically sustainable cash crop. The thick, insulating bark also makes it possible for the tree to survive fires, after which it regrows branches to fill out the canopy.

What makes the cork bark commercially viable is its unique cell structure and its ability to regenerate. A cubic centimeter of cork bark is teeming with air cells (up to 40 million!) and those cells are waterproofed by the waxy suberin. Cork oak bark is durable, light, and bouncy, and once cut, has a suction-cup effect that helps it adhere to the neck of a bottle. There is a long list of uses for cork that's left over after the stoppers have been cut out: flooring, cricket ball cores, insulation panels, sound-proofing materials, fishing rod handles, even devices for the space industry. In Portuguese towns and cities, it is common to see shops selling backpacks, handbags, and even shoes made out of cork.

Modern uses aside, the method of harvesting the bark from the cork oak dates back to the Middle Ages, using an axe that has barely changed in all that time. Virgin (or “male”) cork is cut for the first time from trees about 25 years old. After that, the bark is harvested every 9 to 12 years. Trees can live over 200 years, and one harvest of bark from a single tree can produce enough to cork 4,000 bottles.

In the harvesting process, the bark is peeled from the tree by hand, using only an axe to strip the bark from around the tree. Absolutely no machinery is employed. It can take up to five people to harvest the bark of each tree. Because expertise and finesse is required to peel off the bark without damaging the trunk's cambium layer, harvesters train for about 8 years.

Our cork oaks in Lower Bidwell Park were also harvested periodically; scars from a stripping performed in 1940 and again more recently are visible even now. Click here for a photo taken in 1941 of the local cork oak trees.

In addition to providing cork bark, cork oak groves in Portugal and Spain support another form of agriculture: their acorns provide sustenance to sheep, cattle, and especially hogs. A superior type of ham with a distinctive sought-after flavor is obtained from the Iberian pigs that feed on the fallen acorns.         

Our local cork grove in Lower Bidwell Park provides a window into the past by hearkening back to the ancient farming traditions of the Mediterranean countries, and is a living legacy to John Bidwell's quest to, as local naturalist Rex Burress elegantly stated, grow plants “far from their native origins but brought together to mingle in a new habitat.” Best of all, in my opinion, is our cork oak grove's genetic bond to those trees that make a crucial contribution to good wine.

The Butte County UC Master Gardeners are part of the University of California Cooperative Extension (UCCE) system, serving our community in a variety of ways, including 4H, farm advisors, and nutrition and physical activity programs.  Our mission is to enhance local quality of life by bringing practical, scientifically-based knowledge directly to our community. For more information on UCCE Butte County Master Gardeners and their upcoming events, and for help with gardening in our area, visit https://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-7201 or email mgbutte@ucanr.edu.

Photo Credits:
Cork oak acorns - Bellotas de alcornoque (Quercus suber), Ceuta, España. Xemenendura - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=29528312

Cork oak stripping - Nederlands: Kurkschillen in Santa Margarida da Serra. By Nocampo - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=23045407

Trunk of a Cork oak - Stamm einer Korkeiche (Quercus suber). By Claus Ableiter - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2170249

Cork Oaks Southern Portugal. By KirjavaKinkytail - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=79311214