Research | Biological Control of Leafy Spurge |

Biological Control of Leafy Spurge

At this First Street Pasture, Agriculture and Agri-Food Canada is researching the biocontrol of leafy spurge with the support of MBFI. This page provides information about this particular research and demonstration project; including the background, objectives, and updates.

  • Project Leads:
    • Bev Dunlop, Agriculture and Agri-Food Canada
    • Mae Elsinger, Agriculture and Agri-Food Canada
  • Project Start: June 2015
  • Project Status: In progress (year 2)
  • Location: First Street Pasture

Fact Sheet PhotoFor more information follow this link to a fact sheet

 

About This Project

The overall objective of this project is to investigate a low-input, low-management solution for invasive species management specifically leafy spurge. There are a number of recognized multi-species grazing, feeding, chemical and mechanical options that yield very productive and quick results. However, for larger and/or more extensively managed landscapes, like crown land leases, community pastures, grazing coops, and remote private or rented pastures, a low-input solution is more likely to be adopted and sustained than the more intensive solutions that are being promoted elsewhere. One option is the use of biocontrol agents (special insects) that stifle the performance of leafy spurge in a pasture.

Objectives

  1. To characterize existing leafy spurge and biocontrol populations and their impacts;
  2. To demonstrate how grazing affects the size and efficacy of leafy spurge flea beetle populations;
  3. To establish realistic timelines and expected results for leafy spurge biocontrol; and
  4. To demonstrate how to track biocontrol agent populations, their efficacy, and their migration to aid in invasive weed treatment decisions.

Update

As of August 2017-In July a spurge census was made at 71 points in 4 fields at First Street Pasture, targeting leafy spurge and the 20-year old populations of various insects (spurge flea beetles, gall midges, leaf tier moths and hawkmoths) which suppress this noxious weed. All fields are infested to some degree with leafy spurge, but stem counts and cover in most areas remain within a threshold that keeps them useable for cattle. Of course the worst fields are the ones everyone sees when they drive past the pasture! Most survey locations were occupied by leafy spurge flea beetles at the time of the census, and a significant percentage had population numbers that could be high enough for harvesting and moving elsewhere. Leaf tiers and gall midges were even more abundant. Something about this past fall/winter/spring period has made it a bumper year for these spurge predators!

As of March 2017- The four sites boosted with leafy spurge beetles will be monitored for the second year after release. We will undertake additional work to characterize the leafy spurge population and the various biological control agents present throughout the First Street Pasture. Attend the First Street Pasture Field Tour June 22 to see how we are doing this and many other low-cost pasture improvement projects.

As of November 2016-The first year of monitoring the boosted leafy spurge beetle population at the 4 project sites was completed in 2016. More years of monitoring are needed to isolate and understand the impacts of boosting the beetle population, excluding grazing, site effects, or seasonal weather effects. 

Leafy spurge stem density in each of the 4 beetle study plots lies between 47 and 64 stems/m2.  It is above the upper end of the range of stem densities (5 to 41 stems/m2) found in a peak control year of a study that monitored release sites in Montana and South Dakota1, but short of a threshold around 100 to 120 stems/m2 where cattle use is affected2,3, and short of the potential spurge density if left untreated (as much as 200 stems/m2 on sandy soils)4. It would appear that the leafy spurge on a certain proportion of the area of First Street Pasture is responding to, or being held back by, the various biological control agents that are already on site.

As of Fall 2015 - Four leafy spurge beetle releases were made at First Street Pasture on July 10, 2015. It will take a minimum of two additional years to determine if beetle populations show potential for viable populations and effective control of leafy spurge.

Photo Gallery

Select any image below to view enlargement and/or play slideshow:

Gallery: Leafy spurge on the First Street Site class= Gallery: Black leafy spurge flea beetle, Aphthona czwalinae. Photo accessed July 15, 2016: https://www.ag.ndsu.edu/cpr/entomology/get-ready-to-collect-leafy-spurge-flea-beetles-5-31-12 class= Gallery: Flowering leafy spurge at the First Street Site class= Gallery: Brown Leafy spurge flea beetle (Aphthona. Flava).Photo accessed July 15, 2016: https://www.ag.ndsu.edu/publications/crops/leafy-spurge-control-using-flea-beetles-aphthona-spp class=

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