New weed ID and eradication

Asked August 20, 2018, 5:39 PM EDT

What is this new weed we have seen in the last two years, and how do we get rid of it when it is growing within our periwinkle ground cover.

Howard County Maryland

1 Response

Mulberry weed or hairy crabweed (Fatoua villosa), is a summer annual found throughout the southeastern United States. Named because it is similar to mulberry trees when the weed is less than five inches tall and has less than six leaves. Mulberry weed has prominent hairs on the stems and leaves. The leaves are alternate, toothed, indented with prominent veins, a yellow green color and hairy with a basic triangular shape.Leaves are attached to the stem by a medium length petiole. Stems will secrete a milky sap when cut and the plant has an oily odor.

Flowers are produced quickly on this plant, often on the very young plant, and are tan in color. Seed clusters are pea-sized and have the ability to discharge the seed up to four feet from the plant. This weed produces large numbers of seed so good control from germination on is important.

Mulberry weed seeds require sunlight to germinate. Mulberry weed can grow to a height of four feet. The plant prefers moist, shaded areas in the landscape or nursery, easily moving from pot to pot in container nurseries. Seeds can remain viable in the soil or under mulch for several years.

Mulberry weed can geminate in a wide range of temperatures, from 60 to 90 °F. Do not compost this weed unless you can determine if the process gets hot enough to really kill weed seeds.

Cultural control can include mulching landscape areas and container plants. Hand removal will work but must start early, as they will produce seed on plants less than three inches in height. Pre-emergent herbicides that have been effective include oryzalin (Surflan) and isoxaben (Gallery). Post-emergent application of either contact or translocated herbicides is also effective, but once the seed is formed will not prevent seed dispersal.

Be cautious with the use of glyphosate products in the nursery or landscape where shallow roots or suckers are exposed. Avoid any potential contact with desired species.

Get on top of this weed this year and as soon as it appears in years to come. Eventually you'll exhaust the seed bank (accumulation.)