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.
Johnsongrass rhizome, UC ANR
This non-native weed arrived in Texas in the 1830s and by the late 19th 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.)
Johnsongrass mature plant, UC ANR
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.
Johnsongrass flowering, UC ANR
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.
Johnsongrass seedling, UC ANR
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 firstname.lastname@example.org.