yellow wood sorrrell also known as Creeping Oxalis

low growing weed Creeping oxalis Oxalis corniculata

distribution-of-creeping-oxalis-or-yellow-wood-sorrel-in-Australia

Creeping oxalis (Oxalis corniculata).

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Creeping oxalis (Oxalis corniculata) is a Winter annual or sometimes a perennial herb. It is also known as Yellow Wood Sorrel or Wood Sorrel, and looks similar in appearance to White Clover.

Why is Creeping Oxalis a Weed.

Once it establishes Oxalis corniculata quickly spreads.
It forms dense mats. These mats can choke out grass.
It competes for soil nutrients, light and water.
It spreads by seed and by stolons.
This weed is hard to remove because of its root system.
The leaves are hard to wet. This limits herbicide uptake.
The bright yellow flowers can be an issue.

The leaves of this weed have a lemon flavour. You can use them to make a Vitamin C rich tea. However, it does contain large amounts of oxalic acid (hence its name) which blocks calcium uptake in the body.

How to Identify Creeping oxalis.

It has three heart-shaped leaves.
These alternate trifoliate leaves often cause it to be mistaken for White Clover.
Its flowers are small and bright yellow.
The stolons spread across the ground, They can be up to 60 mm long.
It has light green to purple hairy stems.

Stolons of Wood Sorrel.

There are two easy ways to tell this weed and White Clover apart:

Oxalis corniculata has a small yellow flower. White Clover has pink or white flowers.
White Clover has a distinct white mark on its leaves. Oxalis corniculata doesn’t have this.

This weed is also often mistaken for Soursob or Soursop (Oxalis pes-caprae). The main differences between them are:

Soursob doesn’t have above ground stolons. It reproduces via bulbs.
Wood Sorrel doesn’t have underground bulbs.
The flowers of Soursob are larger.
Soursob favours heavy, fertile, well-drained soils, and frost free areas. Creeping oxalis is more frost tolerant.
Soursob flowers mainly in the Winter. It is dormant over the Summer.

Table of Differences Between Trifoliate Weeds.

	Spreading	Trifoliate	Leaf Shape	Tooth at Tip of Leaf	Toothed Leaf Margins	Annual/ Perennial	Soil Conditions	Habitat	Flowers
Creeping Oxalis	Yes	Yes	Heart shape	No	Smooth	Perennial	High pH	Shade	Yellow with 5 petals
White Clover	Yes	Yes	Smooth rounded	No	Yes	Perennial	High pH	Open areas	White
Black Medic	Yes	Yes	Oval serrated	Yes	Yes	Summer Annual	Low pH	Full sun	Yellow

Summary of Characteristics.

Photosynthetic pathway: It is a C3 weed.

Flower: The flowers of Yellow Wood Sorrel are small with five petals. They are 4 to 5 mm in diameter. It flowers from September to April.

Height: This weed grows to a height of 10 to 35 cm.

Leaf length: The leaves have an egg shape and are 4 to 13 mm long. Each leaf has a distinct notch at the end of it.

Leaf width: The leaves are 11 to 24 mm wide.

Reproduction of Creeping oxalis:

This weed reproduces by seed, and also spreads by stolons.
The seeds travel up to 5 metres out of seed pods.
They can move on shoes, fur and machinery.
The seeds germinate very quickly.

Creeping oxalis (Oxalis corniculata) yellow wood sorrel seed pod

Oxalis corniculata seed pod

Comments: The leaves have a cover of coarse hairs.

Habitat: This weed is a good indicator of soil problems. It prefers moist soils in partial shade, but it is also drought tolerant.

More weed information is in our Weed ID Chart.

Removing Creeping oxalis.

Cultural control is very difficult.
An integrated approach is the best way to manage this weed.
Once it establishes it is difficult to control.
Autumn is an ideal time to control of this weed.

Cultural Control of Creeping oxalis.

Hand pulling, and mowing will not control Yellow Wood Sorrel.
If you do hand weed, you must not leave any plant material behind in the soil.
It can regrow from its deep tap root.
At a low height of cut it becomes more prostrate and grows across the surface.

Weed Management Calendar for Creeping oxalis.

Management Calendar for Creeping oxalis
Winter Annual sometimes Perennial
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Germination
Active Growth
Flowering
Fruiting
Pre emergent herbicide
Post emergent herbicide

Chemical Control of Creeping oxalis.

There are several chemicals to control Yellow Wood Sorrel.
As this weed is hard to wet, use Optispread 1000 to give good contact with the weed.
For large areas, a combination of pre and post-emergent herbicides is the most effective.
Pre-emergents prevent seed growth. You use post-emergents once weeds emerge.
Post-emergents are often more effective on small weeds, rather than older, more mature ones.
Pre-emergents will not work if stolons, rhizomes, or root and stem fragments are left behind when you hand pull weeds.

Pre-Emergents for Creeping Oxalis.

BASF Freehand Herbicide
Echelon Duo.
Indaziflam. This gives good pre and post emergent control in 2020 work.

Table of Pre-emergents.

Product	Active	Group	Rate/ Ha	African Love grass	Annual Rye	Crabgrass	Creeping oxalis	Parramatta Grass	Paspalum	Summergrass	Winter Grass	Crowsfoot	White Clover	$ Cost / m2	Longevity weeks
Barricade	Prodiamine	3	1 to 4 L											143-572	24
Onset 10GR	Prodiamine	3	50 to 150 Kg											275-825	24
Echelon Duo	Oxadiazon	14	300 to 400 Kg											2100-2800	12
Dimension	Dithiopyr	3	1.75 to 3.5L											280-560	18
Freehand	Pendimethalin + dimethenamid-P	3 + 15	100 Kg											1585	12
Specticle	Indazaflam	29	250 ml											495	32
Pennmag	Metolachlor	15	2 L											45	8

Post Emergents for Creeping Oxalis.

2,4-D gives the best results vs this weed.
The Sulfonylureas like Recondo and Duke, are also work against this weed.
The best time to use post-emergents is in the daytime. This is because its leaves fold downward towards the evening.
This is called nyctinasty. You can also see this in Gazania and Morning Glory.
When the leaves fold it makes it hard for chemicals to stick to the leaves.

Post emergents include:

Dicamba. Do not use on Buffalo grass.
Pylex. Do not use this on warm season turf. Use this on actively growing Wood Sorrel. In some cases a single hit of Pylex may not give complete control. In this case you may need to use this again 21 to 28 days later.
Warhead Trio. This is safe on Buffalo grass.
Stature Herbicide. Do not use this in the home garden.
Recondo Herbicide. Do not use this on Buffalo grass.
Weed Blast MA. This is safe on Buffalo grass.
Contra M. Do not use this on Buffalo grass
Duke Herbicide. This is safe on most Buffalo varieties.

Table of Post Emergents for Creeping oxalis.

Product	Active	Group	Rate/Ha	Comments
Casper	Prosulfuron + Dicamba	2 and 4	800 g to 1 Kg	Use from Autumn to Spring. Use high rates in cool months or if there is high weed pressure. Control takes 4 to 6 weeks. Use an NIS at a rate of 0.25 to 0.5% v/v.
Contra M.	Dicamba + MCPA	4	6.5 L	Use in 250 to 400 L of water. Do not use on Buffalo grass. After use do not mow for 2 days before or afterwards or fertilise for two weeks.
Dicamba	Dicamba	4	1.2 L + 3.2 L of 2,4-D Amine 625 g/L	Use a minimum of 1000 L/Ha of water. Do not spray on Buffalo or Bent Grass.
Duke	Iodosulfuron	2	100 g	Always use an NIS or Overtake Oil. Use in 200 to 500 L/ha water.
Pylex	Topramezone	27	0.375 mL/ 100 m2 in 4-6 L water + 0.5% MSO	Allpy twice 21 to 28 days apart. You may see bleaching of Bentgrass after 7 to 14 days. Do not water for 24 hrs post use.
Recondo	Trifloxysulfuron	2	225 g	Use an NIS at 0.25% v/v (1000 g ai/L), 0.42% v/v (600 g ai/L) or Overtake Oil at 1% v/v. Ensure uniform placement onto leaves & into crowns. Water volume is 400 to 800 L/ha. You may need to reapply in 4 to 6 weeks. Allow at least 6 weeks before you overseed. You may see discolouration on Qld Blue and Zoysia.
Warhead	MCPA + Clopyralid + Diflufenican	4 + 12	5 L	You may see discolouration on kikuyu, carpet grass and Queensland blue. Avoid any overlap. Use an NIS.
Weed Blast MA.	Bromoxynil + MCPA	6 + 4	3 to 6 L	Apply in a minimum of 500 L/Ha water. DO NOT mow for 2 days after use.

Non-Selectives for Creeping oxalis.

Glufosinate-ammonium gives control for 4 to 6 weeks. However, Oxalis corniculata will grow back due to the limited movement of this chemical.
Glyphosate. You can use Glyphosate. If water quality is an issue then use ProForce Manta Ray.

The chemicals below are non-selective. They also have a long term residual and stop re-growth of Yellow Wood Sorrel.

Renegade. Renegade stops germination of Oxalis corniculata for up to 12 months. This reduces the need for repeat chemical applications.
Numchuk Quad. This gives post and pre emergent control for up to 12 months.
Cortex Duo. Cortex Duo gives a rapid knockdown of this weed. It has a residual control of up to 3 months. It is also safe to use near trees.

Table of Non Selectives for Creeping oxalis.

Product	Active	Group	Rate/Ha
Glufosinate 200	Glufosinate-ammonium	10	1 to 6 L
Rapid Fire 800	Glyphosate	9	0.9 to 1.35 Kg
Numchuk Quad	Terbuthylazine + Glyphosate + Amitrole Oxyfluorfen	5 + 9 + 34 + 14	20 to 25 L
Cortex Duo	Nonanoic Acid + Oxyfluorfen	14	7 L/1000L
Renegade	Bromacil	5	3.5 to 6.5 Kg