Few, if any plants strike as much terror into the hearts of gardeners and farmers as field bindweed. From the highways of Herriman to the gardens of Garland, from the flower beds of Farmington to the landscapes of Levan, this is one horrible weed.
Field bindweed is one of the toughest and most difficult garden problems in our state. I get more calls about this weed than any other because it seems to defy control and explodes from a small patch into a total infestation.
As I travel through Utah, I find that this weed is everywhere. There are few areas — from low deserts to elevations as high as 10,000 feet — that do not have this pest. In some cases it covers fields that are hundreds of acres in size.
Winning the battle seems almost impossible. Fortunately, there is some hope if you act now.
If you don't recognize the name, the weed grows under several aliases. These include wild morning glory, creeping jenny, European bindweed and a host of other words that are not suitable for printing in this column.
I've always known it has been around for a long time, but I was surprised at the history. While visiting the Metropolitan Museum of Art in New York City, I saw depictions of the plant on carvings of an ancient Egyptian temple that was reconstructed there. As hard as it is to imagine, field bindweed was apparently grown as an ornamental for thousands of years.
Convolvulus arvensis, as it is known by it scientific name, is native to Europe. It likely came to this country in contaminated crop seed and was identified in Virginia as early as 1739. It probably found its way to Utah in the same way.
One reason that bindweed is such a problem is that the plant has a prodigious ability to reproduce. Like the morning glory plant that it is often confused with, it produces a new crop of flowers each day. The one-inch, funnel-shaped flowers vary from white to pink to lavender.
Since the flowers are produced from June until early fall and a new crop blooms every day, the plant is a virtual seed factory. Four rough, dark brown, pear-shaped seeds usually grow in each pod. These seeds have an exceptional survival ability and remain viable for up to 50 years.
It is not the seeds alone that make this such a difficult pest. Bindweed develops extensive above- and below-ground growth soon after germination. A single plant growing from seed in a large container for six months produced 197 vertical roots, each at least 4 feet long for a total of 788 feet. Plants had 34 horizontal underground rhizomes coming from the tap root, which averaged 4 feet in length and gave the plant 136 additional feet of growth. These 34 rhizomes produced 141 new shoots each forming a new plant.
Roots of established plants may extend 20 to 30 feet laterally and some have been excavated as deep as 30 feet below the surface. The roots becomes very fleshy and store large quantities of carbohydrates that feed the plant even after cultivation or spraying.
There are two windows of control for attacking field bindweed. One is right now, when the plant is in full bloom, and the other is in the fall. The timing is largely a matter of biology. When plants are producing flowers, they are expending huge energy resources into producing dozens of new flowers each day. That means their food reserves are very low. As the saying goes, "hit them while they are down." The plants are now churning out their flowers, start it's time to start the battle.
Too many gardeners think bindweed will disappear with a token effort. This is not a battle, it is a war. The weed is not going to go away with one spray, one hoeing, or one of anything else you do. It requires constant and timely attention. Digging or tilling bindweed cuts the roots into sections making more plants.
According to Dr. Steve Dewey, Utah State University Extension Weed specialist, homeowners are not likely to get serious bindweed infestations under control unless they are willing to use herbicides.
"I don't give homeowners much hope for controlling field bindweed without using herbicide except in their lawns. "Turf grass is very competitive and can suppress bindweed. Follow all the practices for good turf grass management, including raising the mowing height, irrigation, and fertilizing regularly," he said.
Glyphosate (Roundup) is probably the easiest and safest product for most homeowners to use. It is non-selective and it will affect any plant it touches. To keep it off of desirable plants, use as a shield an old milk jug or other plastic bottle with the bottom removed. Insert the spray wand into the opening on the top and tap it in place. Set the jug over the top of the plant you want to control and then spray it. That prevents drift or overspray from hitting other plants.
Fortunately, glyphosate does not carry over in the soil. It is relatively nontoxic to humans and is safe to use in most garden situations. It is systemic so it will translocate down into the extensive root and rhizome system and help kill the plant. If you do not kill the underground part of the plant, your control will be inconsistent and temporary.
If there is a glimmer of hope in this battle, it is that the price has gone down on some of the herbicide treatments. Glyphosate is no longer sold as only Roundup because the patent has expired and many companies now sell it. Currently, around 200 glyphosate products are registered in Utah. A partial list of the glyphosate products includes: Avail, Blot-Out, Kleenup, Systemic Weed and Grass Killer, Rodeo, Killzall, Accord, Mirage, Rattler, Ranger and Honcho. Check the label and the product strength before you buy to make certain you are getting the best value.
Glyphosate is currently available as the active ingredient in many products. The liquid products range from a 0.5% ready-to-use to concentrates of up to 53.8% active glyphosate. There is also a dry flowable formulation that is 94% active ingredient. Some of these products need a surfactant, some are ready-to-use. Check each label for specific instructions. Most ready-to-use sprays are too dilute to have effect on bindweed.
Bindweed control in established plantings is difficult. Apply treatments so the herbicide contacts the weed but does not get on desirable plants. Use spray bottles, sponges, or paint brushes to apply herbicides. Apply herbicide to bindweed growing in desirable plants by using a cotton glove over a rubber glove. Dip the glove into weed killer and wipe onto the leaves.
All herbicide treatments work best when weeds are actively growing. Sprays do not work well on plants that are under stress from drought or other problems. Water and fertilize them well for several weeks before spraying. If plants are dusty, wash them and remove dust as it deactivates the herbicide. Avoid watering sprayed areas for six to eight hours and apply the herbicides when there won't be rain.
In spite of all of your efforts, bindweed comes back with a vengeance. Keep up the battle year after year and you may win the war. Give it an inch and it will try to grow forever.
Greenhouse Show on Saturdays
Join Larry Sagers and co-host Don Shafer for the KSL Radio Greenhouse Show on Saturdays from 8 a.m. to 1 p.m. The subject this Saturday is drought-tolerant shrubs.