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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 a couple of non-chemical solutions that are at least 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 three to four weeks of life. In areas where field bindweed is established, shallow cultivation or pulling is an option. However, this must occur without fail every two to three weeks, as plants reach about 6 inches long, to be effective. This regular cultivation additionally must happen for two to seven years to successfully eliminate an infestation.
Otherwise, 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 atop 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, and any runners and seedling that appear on the outside edge of the treated area must be immediately removed. Additionally, the cover and mulch must be left in place anywhere from one to five years. For those using cardboard, the cardboard should be replaced annually. Periodic, small additions of mulch may also be needed for either method to eliminate light penetration.
Now that the growing season is winding down, common post-emergent herbicides including glyphosate (RoundUp type products) and lawn-weed killers (Weed-B-Gone type products are useful tools in controlling the 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, and others, of the University of Minnesota suggests that products containing Quinclorac offers superior control. Dr. Zollinger mentioned that, in his experience, Quinclorac among the best chemical control option. 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 edibles are grown. Other restrictions may exist. Additionally, control similar to what Dr. Zollinger found may not be observed by homeowners because it must be applied in turf situations at labeled lower rates. However, it may still be worth trying. Products such as SpeedZone, Weed Free Zone and 4SpeedXT may also offer enhanced control as compared to standard lawn weed killers. Always read the label before applying any pesticide.