Contributed by Dr. Rui Liu, Assistant Professor – Weed Science, Washington State University Irrigated Agriculture Research and Extension Center (Prosser, WA)
The snack appears if you search “tiger nuts” on Amazon (Figure 1). It’s organic, non-GMO, nutritious, and fit for keto and gluten-free diets. This snack is consumed in South America, Africa, and some parts of Asia. It can also be further processed into gluten-free flour, ice-cream milk-type extract, and vegetable oils. However, the nutlets look just the same as the ones from the weed commonly known as yellow nutsedge (Cyperus esculentus L.).
Yellow nutsedge is a perennial weed species that belongs to the sedge (Cyperaceae) family. It has narrow, grass-like leaves with yellowish-green color. The stem of yellow nutsedge distinguishes it from grasses, as it is upright, triangular, and has three vertical rows. Yellow nutsedge primarily reproduces through underground rhizomes (Figure 2) and tubers (also known as “nutlets”). One tuber can lead up to 1,900 new plants and over 7,000 new tubers in a single growing season.
Washington state (WA) is one of the top potato-producing states in the US. Most of the potato production in WA comes from the Columbia Basin region. Yellow nutsedge is currently this region’s most problematic weed species for potato growers. It competes with potatoes for nutrients and can grow into potato tubers (Figure 3), decreasing the quality of potatoes. The management of yellow nutsedge is critical to the potato industry.
Integrated weed management (IWM) includes preventative, cultural, mechanical, and chemical methods to control weeds, which we are exploring for yellow nutsedge control. Preventing yellow nutsedge from spreading to new areas can be achieved through cleaning equipment before moving it to a new field, using uncontaminated seed sources, etc. Cultural practices like crop rotation using competitive cover crops could reduce yellow nutsedge population density. Mechanical methods such as tillage or mowing can be used during certain times of the growing season. Chemical control includes using effective herbicide programs that include pre-emergence (PRE) and post-emergence (POST) herbicides, combining herbicides with different modes of action, etc.
Figure 1. Picture of tiger nuts on Amazon. Credit: www.amazon.com.
Figure 2. Yellow nutsedge new plant (left) produced from the mother plant (right) through underground rhizomes.
This year, in collaboration with Dr. Tim Waters at Washington State University and Dr. Joel Felix at Oregon State University, we are evaluating some herbicide programs for yellow nutsedge control in potatoes. This study is supported by the Northwest Potato Research Consortium. Herbicides used include Dual II Magnum (S-metolachlor), metribuzin), Eptam 7E (EPTC), and in combinations and at different timings. Please stay tuned for more results later.
Figure 3. Yellow nutsedge grow into potatoes.
While contemplating a potential novel snack choice, I came across an article published in Weed Science in 2002 titled “Yellow Nutsedge Cyperus esculentus L.–Snack Food of the Gods.” The author cited Oliver Goldsmith’s poetry in 1770, The Deserted Village, “No more the grassy brook reflects the day; But choaked with sedges, works its weedy way.” The long history of yellow nutsedge, its presence in many parts of the world, and the plant being either a weed or a crop makes for some intriguing questions. Maybe we should switch perspectives to find ways to use the weed? What are your thoughts? Please leave a comment below.
Disclaimer: Herbicides mentioned in this blog were tested under an experimental use permit granted by WSDA. Applying a pesticide to a crop or site not on the label violates pesticide law and may subject the applicator to civil penalties of up to $7,500. In addition, such an application may also result in illegal residues that could subject the crop to seizure or embargo action by WSDA and/or the U.S. Food and Drug Administration. It is your responsibility to check the label before using the product to ensure lawful use and obtain all necessary permits in advance.