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Controlling Leafy Spurge on Pasture Lands

12/18/2017

Melanie Toppi / Assiniboia TimesDECEMBER 15, 2017 02:03 PM

During the 19th century, a beautiful plant made its way toNorth America. The yellow flowers are bright and vibrant during the summer, andin the fall, the plants turn beautiful reds, purples and oranges.  Although the splendor of these plants canimpress the untrained eye, in reality, they are an invasive nuisance weed thatcan be detrimental to ecosystems and agriculture. 

This plant, leafy spurge (Euphorbia esula), is a veryaggressive invasive plant.  It has a deeproot system and can produce thousands of seeds. Since this plant is exotic, ithas no natural diseases or predators. As a result, leafy spurge can spreadeasily and quickly. Once established, it can outcompete native vegetation andbe very damaging to habitat for species at risk.  Southwestern Saskatchewan is home to manyspecies considered to be “at risk”.  Howdoes one plant impact their habitat? 

These species, such as the Sprague’s Pipit (Anthusspragueii), require native prairie for maintaining and growingpopulations.   The Sprague’s Pipit, forexample, strongly prefers to nest and forage on large parcels of nativeprairie. Leafy spurge, because it is so prolific, replaces the nativevegetation. It changes the structure of the pasture, creating a habitat that isno longer useful to species. 

How is this weed controlled? Well, it is not easy!  There arechemicals will kill spurge; however, they cannot be used near water and can bevery expensive.   Mechanically, plantscan be pulled or dug out at the roots, mowed before seed set, or cultivated oncropland.   A few species of flea beetlesand a species of hawk moth that have been introduced can be effective indamaging the plant and therefore weakening it. Small ruminants, such as goatsand sheep, can also be used to control leafy spurge.  Sheep will consume 50-60 per cent leafyspurge in their diet, and goats will consume 90 per cent leafy spurge.  Grazing can reduce the canopy cover of thespurge and allow native vegetation to better compete.  

Although each method of control has advantages anddisadvantages, no method will completely eradicate leafy spurge with oneattempt. Depending on the amount of leafy spurge, and how long the infestationhas been in an area, it could take several years to reduce the spurge to acontrollable amount no matter which method of control is used.

Lee Sexton has been working with, and learning about, leafyspurge for many years.  He has a lot ofinformation to share, especially about target grazing of leafy spurge. At apresentation this summer, Sexton made the point that “doing nothing about leafyspurge, is the worst thing a person could do”. Landowners need to look at whattheir land is worth now, and what it would be worth in the future. How would a leafyspurge infestation affect the land’s value? How will leafy spurge affect the carrying capacity of a pasture, or thequality of a crop? Investing money into the problem may seem ineffective,however those costs will perpetuate the wanted plant species and increasegrazing capacity, which increases holding capacity.  This, in turn, produces more pounds per acre,therefore more profit.

“Perhaps the best way to deal with leafy spurge is to do anintegrated approach”, said Sexton. Coming up with a plan of action, usingproper tools is important.  Long-term,multi-species grazing along with other biological control (i.e. beetles), is anenvironmentally and economically sustainable solution. 

Small ruminants can consume a substantial amount of leafyspurge. Timing grazing just right will enhance the effects of small ruminantson the leafy spurge. One method used with small ruminants is the “twice-overmethod”.  With this approach, the spurgeis lightly grazed in early spring.  Thiswill cause the spurge to re-grow, with new shoots. Creating these new shootsweakens the root reserves of the plants, making it more vulnerable to futuregrazing. The second time around, the animals will graze the plant again,removing potential of seed development. At this point, the spurge should begrazed heavily. 

Using small ruminants and insects gives the opportunity forcontrolling leafy spurge in hard-to-reach and sensitive areas, such along abody of water. Like any method of control, grazing and insects will take a fewyears to significantly diminish a leafy spurge infestation. Long-term,investing the time and money into controlling leafy spurge will help ensurehealthy pastures and habitat, better profits and will help maintain landvalues. 

The South of the Divide Conservation Action Program (SODCAPInc.) is a local stewardship organization that was formed by stakeholders thatare interested in using the land while maintaining optimal habitat for speciesat risk. SODCAP Inc. has partnered with the Frenchman Wood River WeedManagement area to map existing areas of spurge infestation.  Knowing the size and locations of patches ofweeds is the first step in assisting producers in controlling it. SODCAP Inc. isworking with two ranches in southwestern Saskatchewan, piloting a program tohelp control leafy spurge on native prairie that threatens the habitat forSprague’s Pipit, loggerhead shrike (Lanius ludocicianus excubitorides), andothers. One project involves mainly a chemical control, along with the use ofbeetles in areas close to water. The other project will also use beetles, butwill take an alternate approach to chemical and will use small ruminants.


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