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Tarantula | The wild thing for the week of 9/2/08
Asiatic dayflower has a brilliant blue flower with two obvious blue petals, a hidden white petal and three yellow stamens. The flower lasts one day, hence the name, but the plant produces continuous blooms May through October.
Asiatic dayflower, Commelina communis, is an annual weed in the monocot family that is becoming more of a problem particularly in no-till soybean fields throughout the Midwest. Asiatic dayflower has blue flowers and roots at the ground where it comes in contact with the soil. It forms dense colonies that can cause severe yield losses in both corn and soybean.
Asiatic dayflower leaves have parallel veins and lack petioles. They are two to four inches long and up to 1-1/2 inches wide. The leaves often have hairs on both sides. The plant is a monocot that resembles a dicot. Where the leaf joins the stem, a sheath is formed. This sheath resembles structures called ocrea, which are found on members of the smartweed family.
In the garden, ontrol dayflower by pulling it up while it is small. Make sure that any stem fragments that break off are also removed, or they will take root.
Few herbicides provide acceptable control of Asiatic dayflower in soybeans.
Recently, weed scientists at Iowa State have conducted a number of trials to
identify treatments for the management of this species. This research has revealed
that in soybeans, Spartan, Firstrate, and Sencor are some of the only active
ingredients that will provide acceptable Asiatic dayflower control when applied
preemergence.
Similarly, Firstrate is one of the only conventional herbicides that will provide acceptable control of this species when applied as a postemergence treatment in soybeans, but applications must be made before this species reaches six inches in height.
Many other preemergence and postemergence herbicide treatments that have been evaluated, including Command, Dual, Define, Valor, Resource, Cobra, and Aim, provide little to no control of Asiatic dayflower.
Glyphosate at standard rates in Roundup Ready soybeans will usually only provide some degree of suppression.
Other research has shown that increasing the rates and making at least two applications of glyphosate can provide higher levels of Asiatic dayflower suppression and also that three applications of glyphosate at 0.75 pound a.e. per acre can provide about 80 percent control. Based on all of the available research, it seems clear that preemergence programs that include Sencor or Firstrate are the most effective and economic way to manage this species in soybean.
Dayflowers are a relative of Wandering Jew. A native of Asia, It can grow erect, but often reclines, forming a mat when the series of nodes along its one-foot to two-foot stem take root.