Originally Published In The Deseret News Wednesday, September 25, 1991
This summer I wrote about control of wild morning glory, or more correctly field bindweed. At that time I mentioned the two most important times to attack bindweed were when it blossoms or in the fall when temperatures start to moderate. Gardeners who couldn't or didn't declare war now have a second chance. It is no easier to control the bindweed now, but additional delays let the bindweed spread further through the yard and landscape and it becomes even more difficult to control in subsequent years.
This weed is one of the most smothering and persistent in nature. The vines crawl to the tops of large trees or shrubs, 10 or 15 feet above the ground, and the roots go underneath the soil to a similar depth. It is no wonder that an arsenal of weapons needs to be utilized against the plant.
Fall brings a transition in perennial plants. The abundant food reserves manufactured in the leaves and many minerals are moved to the root system for storage. This enables the plants to survive the winter and start regrowth in the spring. Since the root system is so extensive and so deep, cultivation does little if any good. Plants extract these materials from the leaves and move them to the roots for storage. This provides an opportunity to move weed killers to destroy the roots. When temperatures dip into the low 40s or high 30s it is a good time to break out the weed sprayer. My personal choice is to wait until the tomato vines freeze. This avoids any danger to those plants and still provides green bindweed leaves to spray.
Glyphosate is the best product for spraying in the summer, but is often not the best product to use in the fall and is definitely not the best product to use on turfgrass products. Glyphosate is available in many forms including Roundup, Knock-Out, Kleenup or Killzall. The following table gives the amounts of the different formulations of glyphosate to use on wild morning glory. Ready-to-use gly-phosate sprays are too dilute to have much effect on this plant.
Use the following amounts to make one gallon of spray:
Roundup (40 percent Glypho-sate) 6 Tbsp. 3 oz.
Roundup L&G (18 percent) 12 Tbsp. 6 oz.
Knock-Out (6.6 percent) 1 pt. + 4 Tbsp. 18 oz.
Kleenup (5 percent) 1 pt. + 1 cup 24 oz.
Adding a sticker or surfactant increases the effectiveness of the spray.
For turfgrass areas or areas away from desirable plants, 2,4-D or a combination of products containing 2,4-D are a good choice for bindweed control. 2,4-D is a selective herbicide that kills broad-leaved plants in grasses and is the most common ingredient in most lawn weed killers. Trimec is even more effective than just 2,4-D because it contains MCPP and di-camba. Do not use this product near desirable trees, shrubs or in areas where intended for planting this fall.
One serious problem in treating bindweed is that it often grows with desirable plants. Herbicides are not just weed killers and will damage desirable plants. Apply products selectively using trigger bottles, sponges or paint brushes. If the vines are growing over the top of desirable plants, consider the following treatment. Put on a long rubber glove and over that put a cotton glove. Dip the cotton glove in the herbicide solution, grasp the vines and apply the weed killer by wiping them down with the cotton glove. Application by the paintbrush, sponge or glove method requires solutions three or four times as strong as normal sprays.
In addition to bindweed, there are many other weeds to attack this time of year. All difficult-to-control perennial weeds should be treated. This includes Canadian thistles, clover, quackgrass, bent-grass, tall fescue and orchard grass. The grasses are only controlled with the glyphosate products. This is non-selective, so spray only those spots that you want to kill. Small spots of undesirable grasses can be treated by cutting both ends out of a tin can. Place the can over the weed and treat with the spray. Circular spots can then be overseeded or sodded to return the lawn to its original beauty.
Seriously infested areas benefit from the addition of a landscape fabric mulch. While the fabric does not kill the weeds, it limits the areas where the weed can emerge. This limits the amount of treatment area needed. Realize that the difficulty and the persistence of the weeds requires action. Don't call the nursery or the county agent and complain about your problem, but do something about it. Procrastination does not solve the problem, it only makes it worse and provides additional weeds for following years.
- "FALL PLANTING FOR SPRING COLOR" - Thurday, Sept. 26, 11 a.m. to 1 p.m., Red Butte Gardens at U. of U. Instructor: Peter Lassig, landscape architect, Temple Square.
© 1998 Deseret News Publishing Co.
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