Field bindweed, Convolvulus arvensis, is a highly invasive perennial broadleaf plant often mistaken for morning glory. This weed rapidly establishes itself in lawns, where its twining, vining stems quickly create dense mats that compete with and smother desirable turf. Controlling this persistent pest requires a strategic approach to eliminate the weed without damaging the surrounding lawn.
Identifying Morning Glory and Its Root System
Field bindweed is distinguished by its leaves and growth habit. The leaves are typically arrowhead-shaped, often with rounded lobes at the base, and are arranged alternately along the slender, creeping stems. While the plant produces showy, funnel-shaped flowers that resemble true morning glories, these are smaller, usually white or pinkish, and measure about one inch across.
The difficulty in controlling this weed stems from its extensive and deep root system, capable of reaching depths of ten feet or more. The root structure includes a deep taproot and numerous lateral roots, which store massive amounts of energy reserves. Even small fragments of the lateral roots, some as short as one inch, can regenerate into a new plant, which is why simple surface removal is ineffective.
Non-Chemical Removal Techniques
Non-chemical control methods are effective for small infestations or as part of a long-term strategy, but they require extreme persistence. Repeatedly cutting the vine at the soil line, or mowing over it frequently, starves the plant by preventing photosynthesis. This must be maintained consistently over several years to deplete the stored energy in the deep roots.
Manual pulling is generally discouraged because the brittle roots break easily, leaving fragments behind that can sprout new plants, potentially worsening the infestation. For localized, heavily infested areas, solarization can be used by covering the area with clear or black plastic sheeting. The plastic traps solar heat, raising the soil temperature high enough to destroy the plant tissue. This technique often requires covering the area for an entire growing season.
Targeted Selective Herbicide Application
For established infestations, selective herbicides offer the most effective control method because they eliminate the broadleaf weed while leaving the grass unharmed. The most successful products utilize a combination of active ingredients, most commonly 2,4-D, dicamba, and triclopyr. These systemic herbicides are absorbed by the leaves and translocated throughout the plant, including down to the energy-storing roots.
The most effective time to apply these herbicides is in the late summer or early fall. During this period, the plant is actively moving sugars and nutrients from the leaves down to the roots in preparation for winter dormancy. This downward flow of resources carries the herbicide directly into the root system, maximizing the kill.
Spot-treating individual patches of field bindweed is typically recommended to minimize chemical application across the entire lawn. Always verify that the chosen herbicide formulation is safe for the specific type of turfgrass, as some selective products can damage sensitive varieties like St. Augustinegrass or centipedegrass. Follow-up applications are almost always necessary, often in the following spring or fall, because the weed’s persistence requires repeated efforts.
Preventing Re-establishment in Turfgrass
Long-term suppression of field bindweed hinges on creating a dense, healthy turfgrass environment. Maintaining a higher mowing height (2.5 to 3 inches) is advisable because the taller grass blades shade the soil. This shade reduces sunlight reaching the surface, suppressing the germination of new bindweed seeds and limiting seedling growth.
Proper cultural practices also promote a vigorous lawn that can out-compete the aggressive weed. Deep, infrequent watering encourages the turfgrass to develop a deep root system, making it more resilient to drought and better able to compete with the bindweed roots for water and nutrients. Regular fertilization ensures the grass remains thick and actively growing. Consistent monitoring and immediate spot-treatment of any new shoots are necessary to prevent re-establishment.