Category: Biological Weed Control

Christo Sullivan, Doug Martin, Jordan Billingsley 

About – Yellow Woodsorrel (Oxalis stricta) is a medium-sized edible plant that thrives in lawns and woodlands across the United States and Canada. It can also be found in Europe, Africa, Asia, Japan and New Zealand. The flowers can be used to make yellow, orange, red and brown dyes. Another common name is “Oxalis”, which means “sour” due to its oxalic acid content. Oxalic acid can be toxic when consumed in large quantities because it inhibits the absorption of calcium. Yellow Woodsorrel is a cool season perennial in the Woodsorrel family (Oxalidacea), but may act as a summer annual in certain environments.  It reproduces by seed and occasionally stems.

Identification – Yellow woodsorrel introduces itself from a taproot and forms small, erect, bushy plants up to 20 inches tall. The stems are slender, gray-green, pubescent, slightly ascending, and branched at the base. They will occasionally root at the nodes. The leaves of yellow woodsorrel are alternate with three heart-shaped leaflets. They are pale green, up to 4/5 inch across with long petioles. The flowers are yellow with five petals and are up to ½ inch across. It is often mat forming and more common in cools-season turf species, such as tall fescue. It can be very common in greenhouses and container nurseries because its seedpods can distribute seeds up to several feet.

Control –

Cultural– Hand-weeding is effective before seeds are formed.  As always, the best weed control is a dense turf sward. Proper mowing, fertilizing and irrigation ensure vigorously growing turf.

Chemical –

Many pre and post-emergent herbicides are effective.

Pre-emergent herbicides include:

Pendulum
Atrazine
Ronstar
Barricade
Balan
Dimension

Post-emergent herbicides include:

Basagran
Confront
Dicamba
Atrazine
Turflon
2,4-D
Monument

And many 3-way mixtures sold at in lawn and garden sections  (often labelled as Trimec Southern or for Broadleaf weed control).

 

 

 

 

 

by Ashley Averitt, Justin Hickman, and Kyle Grider

About Star-of-Bethlehem:

Star-of-Bethlehem belongs to the Lily family (Liliaceae), which is closely related to wild garlic and wild onion. It has origins as a cool season perennial ornamental plant, but it has grown into an aggravating weed in home lawns, golf courses, and athletic fields.  This plant spreads by seeds and underground bulbs.  It emerges in the winter to early spring and flowers as temperatures increase, but once summer arrives the plant will enter dormancy.  This plant may be poisonous to grazing animals because it contains high levels of cardiac glycosides, especially in the bulbs.

Identification:

Often confused with wild onion and wild garlic, Star-of-Bethlehem can be distinguished by darker green leaves, a pale green to white mid-rid, and is covered with a waxy coating.  When Star-of-Bethlehem is crushed or mowed it does not produce a strong odor.  Leaves are narrow and linear and will blossom a white, six petal flower with distinct green stripe underneath the petals in the spring.  Star-of-Bethlehem mainly produces from bulbs and rarely from seeds.  The bulb of Star-of-Bethlehem is noticeably larger than that of wild onion and wild garlic.

How to control Star-of-Bethlehem?

Cultural Practices:

• Mowing:  prevents flowering and seed production. Come winter, be sure to raise the height at least 2 inches.
• Hand picking, constantly, but make sure you pull out the entire bulb and bulblets.

Chemical Control

The following postemergence herbicides are available:

Dismiss and products containing Sulfentrazone have been shown to act more rapidly than other products.

Residential applications:

• Dismiss (active ingredient (a.i.)sulfentrazone)

Rate/acre = 8-12 oz/A

• Q-4 (sulfentrazone + quinclorac + 2,4-D + dicamba)

Rate/acre = 7-8 pints/A

• RoundUp Pro (glyphosate) + Mowing (in dormant turf)

Professional Applicators:

• QuickSilver (a.i., carfentrazone)

Rate/acre = 2.1 oz/A

• Surge (a.i.’s, sulfentrazone + 2,4-D + MCPP + dicamba)

Rate/acre = 3 to 4 pints/A

Non Residential Turf:

• Buctril (bromoxoynil)

Rate/acre = 1-2 pints/A (2EC) or 0.5-1.0 pint/A (4EC)

 

 

 

 

 

 

 

by Ethan Flournoy, Doug Martin, and Dustin Miller

Identification

Chickweed (Stellaria media) is a member of the pink or carnation family (Caryophyllaceae). Chickweed is typically 3 to 8 inches tall and can form a mat up to 16 inches in diameter. Leaves are pointed and oval shaped, with entire leaf margins that will grow in pairs from a half of an inch to one inch long. Small white star-like flowers occur in clusters with five deeply lobed petals that can grow up to an eighth of an inch in diameter. These flowers will develop into capsule-like fruits that contain seeds.

Biology

Chickweed prefers moist soils, but it can be found in open sunny areas as well as shaded areas. Chickweed can be found worldwide in any type of climate; however, in Mississippi, it is considered to be a winter annual. It is commonly found near buildings, trees or in landscape beds. Chickweed propogates by seed. It can produce as many as 15,000 seeds per plant.

Control 

There are three types of control for chickweed: cultural, biological, and chemical.

Cultural control can include hand weeding; however, this is most effective while the weed is in its juvenile state. If hand pulled when mature, it can cause significant seed dispersal. In a landscape environment, a two inch layer of mulch can suppress new weeds. In maintained turf, the best prevention is to monitor irrigation and fertilizer applications in order to maximize turf health and competitiveness.

For biological control, grazing has been reported as an effective tool.

Chemical control requires both pre- and post-emergence herbicides. Balan, dimension, and barricade are preemergence herbicides that have good activity on chickweed. Dicamba, Trimec, Surge, and Speedzone are selective post-emergent herbicides often used to control chickweed.

View current weed control guidelines for Mississippi at MSUcares.com.