Control of Leafy Spurge by Grazing Goats -  A Demonstration

Control of Leafy Spurge by Grazing Goats -  A Demonstration

Summary

Objectives

1. To evaluate the biological and economic efficiency of managing leafy spurge with grazing goats.
2. To distribute the data and findings of the research project to practitioners and professionals throughout the region.
3. To develop information materials and displays providing data on the progress and results of the project.

Abstract

The study was set up as a randomized split plot design replicated four times, with grazing and non-grazing by goats as the main plots. The main plots were split into three subplots, which were either spring sprayed with 2,4-D and picloram, fall sprayed with the same herbicide, or not sprayed with herbicide.

Stem counts per square quarter-meter were made to determine baseline data. The spurge plant is a perennial with a substantial root system and powerful crown, capable of sending up new shoots as environmental pressures increase. It is because of this characteristic that stem count over time was determined to be the best measure of debilitation of the plants.

In 1998 there was no significant difference in numbers of spurge stems between grazed and non-grazed plots the first year (after sheep grazing). This is partly because of how the sheep grazed the plots, taking only leaves and seed heads, leaving the stems. Plots sprayed with picloram or 2,4-D during the 1998 season had significantly lower stem counts in the fall. No difference in effectiveness was noted between spring spraying and fall spraying in the first grazing season, nor was there any interaction between grazing and spraying the first year.

In 1999 the plots were again treated with herbicides in spring and fall. Spurge stem counts were again taken prior to grazing and again in the fall following grazing with goats. Fewer goats were used in 1999 than numbers of sheep in 1998. Unlike sheep, goats tended to take the entire plant, stem, leaves and all. Sheep grazing seemed to produce more spurge stems in the spring; however, statistically in 1999 there was still no difference between grazed and non-grazed plots. Grazing of leafy spurge can initiate a flush of new stem growth as the plant compensates for the external pressures. Many deep-rooted plants that re-grow from a crown exhibit increase growth due to mowing or grazing.

Fall spraying suppressed spurge stem counts the most. Conversely, plots not treated with herbicides had the highest stem counts. Fall spraying may have had the greatest effect on stem reduction because in the fall reserves built up all summer are being moved into the crown for storage, along with the herbicides. Herbicides that reach the crown more effectively kill the crown and reduce bud development. Again there is no indication of interactive effects between grazing and spraying.

In the fall of 1999 there still was no significant difference between grazed and non-grazed plots. However, it did appear that the effect of grazing on bud stimulation and subsequent stem growth had abated to some degree. Data collected in the fall of 1999 indicated spurge stem counts were reduced more by the spring than the fall spraying treatment. This contrasted with spring collected data in which fall spraying seemed to offer the greatest control of spurge. This may occur because of the tremendous ability of the spurge root system to resist the effects of herbicides. The results seem to show that, at least for the first few years, while the spurge plant is still robust and hasn’t been debilitated to a large extent by outside pressure, spurge is affected to the greatest extent by the most recent herbicide application.

Dissemination of Findings

The Bannock County Showcase invited the public to a “goat feed” in August 1999 to showcase the project and let people taste goat meat, presenting the idea as a viable alternative enterprise, grazing goats on local weeds and selling the meat. Participants were given information on other projects and studies utilizing goats, the accomplishments of this project, the need to herd goats, visuals on what the goats have done to the leafy spurge plants, costs of the project, and the overall success of the 1999 grazing season. Approximately 60 people attended including the media.

The findings from the study were presented at the stakeholders meeting in November 1999. The Bannock Showcase interagency planning group distributed a project report to Governor Kempthorne’s office, Idaho Department of Agriculture, USDA-NRCS, Bureau of Land Management district manager and state director. It was also provided to the Idaho Department of Lands state and district offices, local landowners, grazing associations and soil conservation districts as well as interested goat owners and entrepreneurs. The two-year report was presented at the University of Idaho Extension annual meeting in spring 2000, the Idaho State Weed Summit (Boise) in January 2000 and the Idaho State Weed Association Annual Meeting (Boise) held last February. A summary will be provided to the state’s 44 soil and water conservation districts for distribution through their newsletters that reach a large percentage of the farm and ranch community in Idaho.

Potential Benefits

To date, the industry has not found a successful program for eradicating or reducing leafy spurge. This project has the potential to improve people’s opinions of biological controls. If goats are used along with chemicals, interseeding, and beneficial bugs we hope may see less chemical use, lower input costs, and fewer pollutants reaching water supplies, while encouraging an alternative livestock enterprise.

Farmer Adoption

This past year three farmers supplied goats to the project, and two of them were actively involved in meetings and planning for the 2000 season. Both will bring more local goats to the 2000 grazing season. One farm family may take over the management of the project. The landowners in the project area all support the project and may band together to purchase goats for the 2001 season, then sell them to the Southern Oregon Goat Producers.

Reactions from Farmers and Ranchers

This year support from the farmers and ranchers involved in the project jumped markedly. They are more engaged in daily management and interested in investing in future projects. Initial indifference and smirks have changed to questions on how they can get more involved. One long-time cattleman, initially very skeptical, is now taking the success story across Idaho and to Washington DC. A stakeholder who did not attend the early planning meetings now attends them all and wants to get more involved. These reactions may seem small but to the project planning team they are large steps toward the future of the enterprise.

Producer Involvement

Fourteen producers or landowners were involved in this project. Two cooperators represented the rest of them and attended all the planning meetings and assist in management decisions. One landowner acts as liaison between the other landowners, agency personnel, and managers/herders. He lives close to the base camp and oversees the needs of the project. The other landowners contribute by attending planning meetings, assisting in management decisions, providing supplemental hay, and getting the word out to other farmers and ranchers in the area. They will probably be purchasing goats for the 2001 season.

Future Recommendations

There is a need to continue grazing the spurge, as the plants are not yet debilitated to the extent that differences between grazed and non-grazed plots are clear. We need to be patient to see how long it takes for grazing to begin to control the capacity of the crown to put out new shoots.

Additionally, we need more time to see when the grazing effects kicks in and to see if an interactive effect develops between grazing and herbicide application timing. It will also take at least another year to see if spring or fall application of herbicides control spurge to a greater extent.

This summary was prepared by the project coordinator for the 2000 reporting cycle.