May 1, 2023
Burcucumber (Sicyos angulatus) is a climbing summer-annual viny weed. It can grow upwards of 20 to 30 feet in length, which can make it challenging at harvest in corn and soybean crops. Typically, it is found in fencerows, flood plains, low-lying areas, and other moist areas of crop fields.
This weed can be identified by its unique climbing nature. Burcucumber has fibrous roots that spread from a main taproot, long hairy stems, tendrils that fork out from the sides of leaves, and pubescent, large, alternate leaves that are lobed with 5 points. The fruits are large, firm, and round, and are covered with barbed bristles, hence the plants common name. Wild cucumber (Echinocystis lobata) can be confused with this weed but is much less likely to be found in crop fields.
Figure 1. Burcucumber leaves and fruit. Picture courtesy of and used with the permission of Photo courtesy of Theodore Webster, Ohio State Weed Lab, The Ohio State University, Bugwood.org
Figure 2. Burcucumber vine showing tendrils and hairy stem. Picture courtesy of and used with the permission of Bruce Ackley, The Ohio State University, Bugwood.org.
Due to its climbing nature, it wraps and twines around corn plants, intercepting sunlight, lodging the corn plant, and potentially causing a more difficult harvest. You may see infestation in certain isolated places throughout the field with heavy lodging in those areas. Burcucumber flowers in August and flowers until a killing frost arrives. Burcucumber seeds have a very hard seed coat that enables it to have prolonged dormancy. Consequently, meaning once established, the problem is likely to reoccur for years. Thankfully, it is not a prolific seed producer, which means it can be controlled with proper management.
When managing burcucumber, tillage is an important factor. Tillage passes could encourage additional flushes of burcucumber due to prolonged dormancy, a wide emergence window, and the ability to emerge from 6-inch depths. Consider converting fields to minimum tillage or no-tillage to keep buried seed from being activated by sunlight.
Herbicides can be used to control this weed effectively if using a two pass (PRE and POST) program. A one-pass program may miss later flushes of this weed due to its long emergence window. The ability of burcucumber to emerge from deep soil depths makes most residual-based herbicides less-effective at stopping its emergence.
Recommended two-pass programs in corn include: PRE products containing atrazine and/or isoxaflutole (Balance® Flexx Herbicide, Corvus® Herbicide + atrazine), and mesotrione and bicyclopyrone (Lexar® EZ Herbicide, Acuron® Herbicide) followed by POST products such as dicamba (DiFlexx® Herbicide), mesotrione (Callisto® Herbicide/Halex® GT Herbicide), atrazine, glyphosate in Roundup Ready® Corn 2, and glufosinate (Liberty® Herbicide) in LibertyLink® corn). (POST herbicide applications should be made when burcucumber plants are less than 12-inches long and have not started vining.)1
In soybean, early canopy closure can help keep late weed flushes from occurring and may be an advantageous strategy. Based on research conducted at The Pennsylvania State University, soil-applied PRE products that contain chlorimuron and/or metribuzin provide effective early-season control of burcucumber. These products include Authority® MTZ Herbicide, Panther® Pro Herbicide, Valor® XLT Soybean Herbicide and others. Be mindful of carryover issues with some of these herbicides in high pH soils.2
Glyphosate in glyphosate-resistant soybeans provides good control of burcucumber. In XtendFlex® Soybeans (dicamba-resistant) or Enlist E3® Soybeans (2,4-D resistant), registered dicamba or 2,4-D containing products, respectively, can be used in conjunction with glyphosate or chlorimuron. Glufosinate (Liberty® Herbicide) + ammonium sulfate (AMS) can be applied as a late-POST application in XtendFlex® Soybeans or Enlist E3® Soybeans to control late-emerging burcucumber plants.
Sources
1Jha, P. and Vittetoe, R. 2022. Managing burcucumber in corn and soybean. Integrated Crop Management News. Iowa State University Extension and Outreach. https://crops.extension.iastate.edu/cropnews/2022/11/managing-burcucumber-corn-and-soybean
2Lingenfelter, D. 2018. Burcucumber management in corn and soybean. Penn State Extension. The Pennsylvania State University. https://extension.psu.edu/burcucumber-management-in-corn-and-soybean#:~:text=Post%20herbicides%20provide%20the%20best,(Callisto)%2C%20and%20glyphosate/.
Websites verified 3/9/23.
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