Solution sheet Oxalis – Warm Season // The Problem Oxalis or yellow woodsorrel (Oxalis stricta L.) is an upright growing perennial weed, growing up to 20 inches high if left unmowed. Yellow woodsorrel is a perennial, spreading by rhizomes or rooting at lower nodes. Reproduction is primarily by seed so it acts as a summer annual, dying back with cold temperatures as one moves north into the transition zone. Another similar species more prevalent in the west is creeping oxalis (Oxalis corniculata L.), which spreads horizontally by stems and stolons. Florida yellow woodsorrel (Oxalis florida) is also similar to yellow woodsorrel, but with slightly narrower stems and larger leaves. What To Look For Oxalis species are most competitive in thin turf, especially next to sidewalks and drives or in spring establishments. The most obvious characteristic of all oxalis species is the bright yellow flower with five petals. Oxalis flowers mainly during spring and into early summer, although it can be found year-round in the southeastern United States. Seed pods are formed after pollination and resulting seeds can be ejected explosively up to 10 feet from the plant. All species have alternate leaves at the end of a long petiole, and are divided into three partly-folded, deeply-cut, heart-shaped lobes with hairy margins. The foliage has a sour, acrid taste. // The Solution Improving turf density will most effectively minimize long-term infestations of oxalis. Raising the mowing height and increasing fertilization where appropriate, proper irrigation and regular aerification are the primary cultural tools to increase turf competition and density. Since oxalis reproduces primarily by seed, the most effective and efficient control is with pre-emergent herbicides in early spring. Multiple applications may be needed. Specticle® will suppress oxalis species when applied prior to germination. Typical two-, three- or four-way phenoxy herbicides can control oxalis after germination, but multiple applications are required and control can be marginal. Instead, applications of Celsius® WG or Tribute® Total will provide excellent post- emergent control. Be sure to read and follow label directions with all herbicides. Pay special attention to precautions on using herbicides on specific species/cultivars of turf; some warm-season species can be sensitive to herbicides.

Oxalis reproduces by seeds and rhizomes, and can form a fairly-dense mat in thin turf areas. (Bayer) Rate Rate Solution1 Application Notes (per 1,000 sq ft) (per acre)

Apply in early spring prior to weed seed Specticle G 2.3 - 4.6 lbs 100 - 200 lbs germination. Do not exceed 9.2 lbs/1,000 sq ft or 400 lbs/A in a 12-month period.

Apply in early spring prior to weed seed germination or combine with Celsius WG for knockdown plus residual control. Split or multiple Specticle FLO 6 - 10 fl oz application program rates are available on the Specticle FLO label. The maximum allowed rate does not exceed 18.5 fl oz/A in a 12-month period.

A second application may be required for maximum control. If weeds are showing signs of recovery, make Celsius WG 0.085 oz 3.7 oz a second application 2-4 weeks after the first. Do not exceed 7.4 oz/A/year (365 days) for all applications.

Do not apply more than a total of 6.4 oz/A Tribute Total 0.073 oz 3.2 oz (0.147 oz/1,000 sq ft) of product per year.

1See the product labels for complete use instructions. Always read and follow label instructions carefully.

The bright yellow flower of oxalis is easily recognizable. (Bayer) Yellow flowers and leaves with three petaled heart-shaped lobes are typical in oxalis. (Bayer)

ALWAYS READ AND FOLLOW LABEL INSTRUCTIONS Bayer Environmental Science, a Division of Bayer CropScience LP, 5000 CentreGreen Way, Suite 400, Cary, NC 27513. For additional product information, call toll-free 1-800-331-2867. Not all products are registered in all states. Bayer, the Bayer Cross, Celsius, Tribute, and Specticle are registered trademarks of Bayer. © 2019 Bayer CropScience LP. ES-818-LLWS-202-A-R2