Leafy Spurge  (Euphorbia esula)

All plant descriptions and control methods courtesy University of Nevada Cooperative Extension

Leafy spurge, a Eurasian native, has spread aggressively in rangelands throughout the northern United States. In Nevada, it is present in Elko, Humboldt, Washoe, Nye, and White Pine Counties in rangelands, pastures, and disturbed soils. It can cause severe irritation to the mouths and digestive tracts of some domestic and wild grazing animals. The extensive root system of this long-lived perennial may grow to depths of 40 feet or more. Efforts should be made to find and eradicate new infestations before this happens. Once the root system is developed, complete control may never be achieved. Seed capsules explode when dry, shooting the seeds up to 15 feet. Seeds remain viable in the soil for up to eight years. With long-term diligence, leafy spurge numbers can be reduced so that it does not dominate extensive acreages.

Distinguishing features:

• The plant grows up to 3 feet tall with a deep root system.  
• Its alternate leaves are narrow and linear with smooth margins that are ¼ inch wide and 1 to 4 inches long.
• The true flowers are small, light-green, and enclosed by a pair of larger, yellowish green, heart-shaped bracts.
• Flowering occurs from June through midsummer.
• The shoots are erect and pale green.
• Stems and roots have a milky latex that is damaging to eyes and sensitive skin.  
• Pink buds, capable of forming new shoots and roots, are common on crowns and roots.
   

CONTROL MEASURES

Most Effective Strategy:
Leafy spurge is one of the most difficult of Nevada’s noxious weeds to control. Its extensive root
system ensures the plant adequate water under most conditions, and food reserves to carry it through harsh times, including
many control treatments. A combination of herbicides and cultural controls have proven to be the most effective treatment.
Cleaning equipment and using weed-free hay limits the number of infestations. Finding leafy spurge in its first year of establishment
and initiating control efforts then is critical. Established infestations should be regularly and intensively grazed by sheep
or goats to limit top growth, seed production, and its spread. Follow summer-long grazing with a fall herbicide application. If
that is not possible, repeated spring grazing will slow its spread. Efforts may include seeding with appropriate species to
provide competitive vegetation. A long-term effort over many years is required to have any effect on an infestation. Missing
even 1 year of control reduces the effectiveness of the past efforts.

Mechanical Control:
Intensive, repeated cultivation throughout the growing season is somewhat effective in reducing aboveground
plant materials. Mowing and burning reduces seed production, but plants will regrow from the perennial root system.

Cultural Control:
Repeated grazing during the growing season by sheep or goats is useful in keeping leafy spurge from
spreading. It does not eliminate plant populations due to its extensive root system, so grazing must be continued frequently.

Biological Control:
More than one biotype of leafy spurge has been introduced into the United States. Many of the introduced
biocontrol agents are specific to an individual leafy spurge biotype and will not thrive on other biotypes. The minute
spurge flea beetle (Aphthona abdominalis) and a defoliating moth (Simyra dentinosa) have been released in Elko County. The
brown-legged leafy spurge flea beetle (Aphthona lacertosa) has been released in Humboldt County. How well these species
become established in Nevada, reproduce, and infest leafy spurge has yet to be determined. Some of the research conducted
in the northern Great Plains on biocontrol agents for leafy spurge is applicable to Nevada. Other flea beetles that are available
include: Aphthona cyparissiae, A. czwalinae, A. flava, A. nigriscutis. Five moths, Chamaesphecia crassicornis, C. empiformis, C.
tenthrediniformis, C. astitformis, and C. hungarica, feed on the roots. The Italian fly (Dasineura sp. nr. capsulae), the hawkmoth
(Hyles euphorbiae), an Italian bug (Oncochila simples), and another fly (Pegomya euphorbiae) feed on various parts of
the plant. Other biological control agents are being tested regularly for release.

 

Read and follow the label. It is the law!

Chemical Control:

Picloram (Tordon®)
Rate: Apply Tordon 22K® at 2 to 4 pints per acre or 1/2 to 1 pound a.e. per acre. Spot treat at a rate up to 2 quarts per
acre (1 pound a.e. per acre). At lower rates, tank mix with 1 pound a.e. per acre 2,4-D to improve control.
Time: Apply at the true flower stage of growth or apply to fall regrowth. Reapply when the level of control falls below
80 percent.
Remarks: Adjustment of the application rate affects the selectivity of picloram. At the rates recommended, picloram will not
damage established perennial grasses.
Caution: This restricted-use herbicide must be applied by, or its application supervised by, a certified applicator. Follow the
label directions. Picloram remains active in the soil for a long time. Do not contaminate water.

Imazapic (Plateau®)
Rate: Use 8 to 12 ounces of Plateau® per acre or 2 to 3 ounces a.i. per acre.
Time: For best results, apply in the late summer or fall (August through mid-October). Consecutive year applications will
optimize long-term control. Applying Plateau® at 12 ounces per acre in the spring or fall, or 4 ounces per acre in the
spring following an 8-ounces per acre fall treatment, may result in excessive injury to cool season grasses in some
areas. For best results, always use a methylated seed oil at 2 pints per acre. Nitrogen fertilizer applied at a rate of
2 pints per acre may also increase leafy spurge control.
Remarks: Plateau® may not control some naturally occurring weed biotypes (plants within a species with a slightly different
genetic makeup) with resistance to this and/or other herbicides with an ALS/AHAS enzyme inhibiting mode of
action. When treating ALS/AHAS resistant biotypes, tank mix Plateau® with an appropriately registered herbicide
having a different mode of action and sequentially treat the area to ensure control.
Caution: No grazing restrictions exist, but do not harvest hay for at least 7 days following application of Plateau®. When
cool-season grasses such as bluegrass and smooth brome are present, do not exceed 8 fluid ounces per acre.

Dicamba (Clarity™, Diablo™, Fuego™, Vanquish™, Veteran™, or Banvel®)
Rate: Use 1 to 2 pounds of Dicamba per acre.
Time: Apply when plants are in the rosette stage of growth.
Remarks: Use higher rates when treating dense or tall vegetative growth. Use in a tank mix with other herbicides to increase
its effectiveness. Check the label for tank mixing instructions.
Caution: Avoid drift to sensitive crops. Read and follow the label directions.
 

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