What Can I Use to Kill Morning Glories?
Morning glory, also known as field bindweed or creeping jenny and scientifically referred to as Convolvulus arvensis, is a perennial weed known for its fast growth and resilient nature. Bindweed can be extremely difficult to control, as this plant is extremely deep-rooted, reproduces by root or seed and penetrates many mulches. The best way to control field bindweed is with an intensive combination of vigilant monitoring and removal, competitive cropping and herbicides.
Field bindweed can spread by rhizomes, roots or seeds, which can remain dormant in soil for over 20 years. A single plant can produce 25 daughter plants within a single growing season. These plants form dense nets in fields, gardens or on turf, competing with crops or grass for light, water and nutrients.
Pulling or hoeing field bindweed may prove ineffective for any but the lightest infestations. However, if the top growth on the bindweed is removed at least every two weeks by cutting or pulling at ground level, the plant will be unable to photosynthesize and will suffer reduced vigor. After one or two growing seasons of this continual removal, the morning glory may be eliminated or at least much easier to treat effectively with a herbicide.
Mulching or Covering
Mulching can be an effective control if the materials used cannot be penetrated by the bindweed. Fabric weed barriers can be used as long as the entire area is mulched to ensure that no shoots can emerge between fabric pieces or along edges. If plants do emerge around or through the barrier, they can be manually removed or treated with a herbicide. Bindweed can easily penetrate plastic mulches and even extremely thick layers of organic materials that would smother most plants.
Wherever the problematic morning glory has become well-established, herbicides are the most effective and practical control method. Glyphosate or dicamba can be used for spot applications. The bindweed must be treated with a herbicide that can move through the root system to kill growth nodes in the root system. Herbicides should be applied when the bindweed is actively growing. Fall applications shortly prior to the first frost are most effective. Only apply herbicides if the bindweed is not drought-stressed. Drought-stressed bindweed slows down internal activity, decreasing the rate of herbicide transport. Herbicides should be applied carefully and according to manufacturer directions.
If the bindweed is problematic on turf, use proper cultural practices to maintain a healthy lawn. Long, thick turf will help to crowd out and starve bindweed. As with turf, a well-managed garden with crop plants that block most sunlight can prove an effective limitation to field bindweed. For example, a productive patch of sweet corn can shade out the morning glory and reduce available root space. Additionally, the area around the corn can be easily weeded with a hoe every two weeks or so.