Petty Spurge (Euphorbia peplus)
Petty Spurge (Euphorbia peplus) aka Cancer Weed is a small annual herb. Its milky sap contains harmful substances, and if it gets on your skin it becomes red and blistered. It can also sting and burn the eyes if they come into contact with it.
Petty Spuge (Euphorbia peplus) is one of the most common search queries on the QLD Poisons information Centre website.
People call Petty Spurge Cancer Weed, because of ongoing studies into its sap for the treatment of skin cancer, leukemia, warts and sunspots.
Many herbicides fail to control it and hence it has spread rapidly in many parts of the world.
The distribution map for Petty Spurge is courtesy of The Atlas of Living Australia.
After you read this, you will be able to:
- Identify Petty Spurge or Cancer weed.
- Know the habitat of Petty Spurge or Cancer weed.
- Know the best cultural and chemical options to control Petty Spurge.
How to Identify Petty Spurge.
Category: Annual Broadleaf (Dicot)
Flower: The flowers are small, yellowish-green and held in leafy bunches. The unusual flowers of Petty Spurge appear between April and October
Height: Petty Spurge is up to 40 cm in height and has smooth, hairless stems that are red at the bottom and green at the top.
Leaf length: The thin, soft leaves are oval, rounded to obovate, pale green in colour, and 4-25 mm long.
Leaf width: 4-17mm wide
Reproduction: Petty Spurge reproduces by seeds that disperse by water and soil movement. Plants produce between 260 to 1,200 seeds, and mature in 12-14 weeks.
Seedlings emerge through the year except over the Winter. Most seed germinates within a year at a depth of 5 to 10 mm, and only a few seeds emerge in the next 5 years. Seeds germinate straight away in the Summer. In contrast, seeds in the Autumn stay dormant until the Spring.
Its seeds disperse explosively, and can still germinate after 100-years
Comments: Milky white sap
Habitat: A common weed around buildings, gardens and disturbed areas. It prefers moist, shady locations.
For more information on weeds, check out our weed ID Chart.
How to control Petty Spurge.
You can control Cancer weed by cultural and chemical means, but you can best manage this weed with an integrated approach.
Cultural control.
One of the best control measures for Petty Spurge or Euphorbia peplus in turf, is to maintain a competitive stand of grass. This weed is not a very strong competitor and gains a foothold by being an opportunist.
When open areas develop due to stress, disease, lack of fertility, insects, or high wear, light penetrates to the soil surface, and allows Petty Spurge to germinate. That’s why you also find this weed in open garden beds, paths and areas where it doesn’t need to compete with other plants.
Once Petty Spurge establishes itself, its too late to control it with cultural practices. For example, at this stage mowing doesn’t work as Petty Spurge tends to grow close to the ground.
- If you raise the height of cut when you mow to 50 mm or more in tall fescue or perennial ryegrass ir reduces initial invasions.
- Check the thatch levels of your turf. They should be less than 12 mm.
- Constantly monitor problem areas, so you can hand pull new plants before they seed. Take care as you weed, since plants that you hand pull often break at the stem. This then leaves the root and several buds or a single stem from which it regrows.
- Hand weeding is effective on small areas to control seedlings. It’s best to begin when plants are young, and before plants seed.
- Wear gloves when you hand weed, since the sap is a skin irritant.
- Dispose of any plant material off site.
- Wash mowers and machinery free of soil and seed, if you move from infected areas to weed free areas.
Chemical control of Petty Spurge.
Cancer weed or Euphorbia peplus is resistant to many kinds of herbicides, and is not easy to control by chemical methods. The aim of control with this weed is to reduce the seed bank and keep it at a low level.
Pre-emergent weed killers prevent outbreaks of Petty Spurge if you use these before seeds germinate in late Winter. You need to time the application so that it occurs before soil temperatures get higher than 16°C at a depth of 25 mm.
Pre-emergent options include Pendimethalin (Battalia 435), BASF Freehand, Isoxaben (Gallery) and Dithiopyr (Dimension EW). Home gardeners can only use Battalia 435, Dimension EW and BASF Freehand.
US work has shown that Indaziflam gives good pre-emergent control of Painted Spurge, which increases the options for control in warm season turfgrass.
Post emergent options include Warhead Trio (not registered for this), 2,4-D, Bentazone, Amicarbazone, Glufosinate-ammonium and Glyphosate, although 2,4-D and its combinations don’t control large mature Spurge plants.
You can use Glyphosate as a non selective option to control this weed. If you use Glyphosate and water quality is an issue then we use ProForce Manta Ray.
