One of the worst weeds to invade the American West is field bindweed, also commonly but incorrectly known as morning glory. There is nothing glorious about it. It is a vining perennial plant that sends roots to 30 feet deep and spreads from both seeds and root runners. It flowers and produces seeds from late spring to mid fall.
During the growing season, there are non-chemical solutions that can be moderately successful. One includes complete removal of seedlings just as they emerge from the soil. New plants lack the ability to produce runners that generate other new plants for the first 3 to 4 weeks of life. In areas where field bindweed is established, shallow cultivation or pulling is an option. However, this must be done every 2 to 3 weeks as plants reach about 6 inches long, to be effective. This regular cultivation additionally must happen for 2 to 7 years to successfully eliminate the weed.
Smaller infestations can be covered with black plastic sheeting or landscape fabric. After one of these is laid out, place 2 to 3 inches of mulch on top of the plastic or fabric to eliminate light penetration. Another similar method involves covering with overlapping cardboard pieces and then placing several inches of mulch over the cardboard. For either of these to be successful, the cover must be placed a couple of feet beyond where the bindweed stops. Any runners and seedlings that appear on the outside edge of the treated area must be immediately removed. The cover and mulch must be left in place for 1 to 5 years. If using cardboard, it should be replaced annually. Periodic, small additions of mulch may also be needed to eliminate light penetration for either method.
Now that the growing season is winding down, common post-emergent herbicides including glyphosate (Roundup-type products) and lawn-weed killers (Weed B Gon-type products) may help control this problem plant. Glyphosate is non-selective and should be used in open fields and other areas that lack desirable plants such as turf, flowers, shrubs and trees. To improve its effectiveness, mix glyphosate with 2, 4-D or another general lawn-weed killer.
Of the chemical control options available, recent research from weed scientist Richard Zollinger, University of Minnesota, suggests that products containing Quinclorac offer superior control. In the homeowner market, Quinclorac is a common ingredient of lawn-weed killers additionally labeled for crabgrass control. However, it can only be applied to lawn grass and not in areas where edibles are grown. Additional restrictions may be noted, so be sure to check the label before applying. Products such as SpeedZone, Weed Free Zone and 4-Speed XT may also offer enhanced control compared to standard lawn-weed killers.
Direct column topics to Julene Reese, Utah State University Extension writer, Logan, Utah, 84322-4900, 435-797-0810, email@example.com.