Two grass weeds in West Virginia that look very much alike are johnsongrass and shattercane. They can be very easily differentiated if you know what to look for.
Johnsongrass is found throughout West Virginia. Johnsongrass is a perennial weed, which means it grows for more than two years. It can reproduce by seeds or vegetatively by rhizomes. The seed heads of johnsongrass and shattercane are distinct. Johnsongrass has an open panicle seed head with few seeds (Figure 1).
Shattercane is found in the northern part of West Virginia. It is not as prevalent as johnsongrass in West Virginia. Shattercane is an annual plant, which means it grows only one year and then dies. Shattercane reproduces only by seed. Shattercane has a much more compact seed head with more seeds than johnsongrass (Figure 1).
Johnsongrass can be identified by its large thick rhizomes. Shattercane does not have rhizomes (Figure 2). Johnsongrass plants can germinate from these rhizomes.
Shattercane can be distinguished from grain sorghum by pulling a seed from the seed head. If the rachis (Figure 3) breaks in the middle of the rachis, then the plant is grain sorghum. If the seed separates from the rachis where the rachis joins the seed and the rachis is swollen, then the plant is shattercane (Figure 4). You will need a magnifying glass to see if the rachis breaks at the seed or in the middle of the rachis.
Johnsongrass and shattercane can both be controlled by postemergence herbicides in corn. Accent herbicide provides good control of both johnsongrass and shattercane. Beacon will provide slightly less control than Accent on johnsongrass. Basis, Basis Gold and Exceed also have activity on johnsongrass and shattercane. With genetically engineered corn, Poast Plus, and Pursuit can be used on corn for johnsongrass and shattercane control.
Land infested with johnsongrass and shattercane can also be rotated to alfalfa or small grains. Johnsongrass and shattercane will be weakened by the frequent cutting in alfalfa. Poast Plus herbicide can be used in alfalfa to help control johnsongrass and shattercane. In small grains, Roundup Ultra can be used to control johnsongrass after the small grain has been harvested.
There are several herbicides in soybeans that will do an excellent job of johnsongrass and shattercane control. Assure II, Fusilade, Roundup Ultra, and Select all provide excellent control. Poast Plus, Pursuit and Fusion will also provide very good control.
There are also options available for soil applied herbicides in both corn and soybeans, but most require incorporation and are not as effective as the postemergence herbicides.
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