Burcucumber and wild cucumber (AKA wild balsam apple) are weedy members of the cucumber family. They are frequently found along river bottoms and other wet areas, and may cause serious problems due to their ability to climb and smother small to medium sized trees. Burcucumber is more likely to move into crop fields than wild cucumber, and it can be a serious problem due to its competitiveness and interference with harvest. While both species are found throughout Iowa, wild cucumber seems to be more prevalent in western Iowa.
Burcucumber leaves are circular with 3-5 shallow lobes, and reach diameters up to 8” (Figure 1). The stems have stiff hairs, and produce coiled tendrils that allow the plant to climb on other vegetation or surfaces. Leaves of wild cucumber are more deeply lobed, having a star-shaped appearance (Figure 2). Wild cucumber produces a small (2” long) fruit that resembles a cultivated cucumber, whereas burcucumber produces a cluster of 3-10 small, bristly fruit, each up to ¾” long.
Most questions I receive regarding these weeds is what to do about them climbing trees in shelterbelts. Since they are annuals the goal should be to prevent seed production to minimize future problems. Most plants I've seen haven't produced seed yet, severing the stems near the soil line should accomplish the goal of zero seed production. Many people are interested in a herbicide that can selectively kill the viney weeds without damaging the tree; unfortunately there isn't anything that fits this bill. Mulches are the best option for controlling weeds around trees, but this may not be feasible for large shelterbelts/windbreaks.
On a plant by plant basis, few weeds are more damaging to crop production than burcucumber. Not only does the viney habitat allow it to completely shade out both corn and soybean, but it also greatly reduces harvest efficiency. The seeds germinate throughout the growing season, complicating management. Fortunately, limited seed production compared to other agricultural weeds limits how quickly it invades fields. Because of its weedy potential, it is best to take preventative steps and control any plants that show up near crop fields.
Figure 1. Burcucumber leaves
Figure 2. Wild cucumber leaves.