Davison, J., Powell, P., Schultz, B., Creech, E., and Singletary, L. 2011, Needs Assessment for Noxious Weeds in Churchill County: Part 3 of 5 - Spread, Detection and Prevention of Weeds, University of Nevada Extension, FS-2011-74


This fact sheet is the third in a series of five publications designed to examine noxious weed issues that affect Churchill County. This publication discusses the results from a needs assessment conducted by the University of Nevada Cooperative Extension (Extension) to discuss the spread, detection and prevention of weeds. The first publication in this series identified problem weeds, approaches and methods for control. The second publication discussed problems and obstacles to weed management. Subsequent publications in the series will look at 1) herbicides and the criteria used for their selection and timing of use, and 2) priority research and outreach programs.

Churchill County encompasses 5,023 square miles in western Nevada and lies approximately 60 miles east of Reno. Over 89 percent of the land in Churchill County is owned by the federal government. The only incorporated city in Churchill County is Fallon. Churchill County has a total population of 26,859 residents (2009), with 9,113 people residing within the Fallon city limits.

The Lahontan Valley, located in Churchill County, is the primary agricultural production area with 210,752 acres defined by the county as “agricultural” lands.These lands are classified into four use types, including cultivated (30,568 acres), pasture (8776 acres), grazing (160,308), and meadow (~11,100), with water rights assigned to 39,877 acres. Most of the county lands are classified as rangelands or are covered with water.

In 2009, the U.S. Department of Agricuture reported that there were 529 farms in Churchill County, averaging 248 acres in size. The average farm in Nevada is nearly eight times as large as the average farm in Churchill County. Direct output value from the agricultural sectors in Churchill County in 2007 was $122.6 million dollars, of which $54.8 million was related to crop sales and $67.8 million to livestock or livestock product sales. The average economic multiplier value for the agricultural sector was 1.43, meaning that the agriculture sector generated an additional $52.8 million in economic activity for a total economic impact of $175.4 million dollars. In addition, during 2007 the agricultural sectors generated a total of 531 jobs directly tied to agriculture and an additional 446 jobs generated by the economic activity that the agricultural sector provides.

The county includes transportation corridors I-80, Highway 50, Highway 93 and two transcontinental rail lines. Churchill County receives irrigation water from the Carson and Truckee rivers. All of these corridors act as agents for the introduction and spread of noxious weeds. Several noxious weeds have established on lands adjacent to these rivers. These weeds, if not controlled, could dramatically reduce the yield and quality of the crops produced in Churchill County. Because most crops produced in Churchill County are used for livestock feed, reductions in livestock and livestock product sales are another possible result. Both will negatively impact the economic contributions that the agricultural sectors make to Churchill County.

Survey Methods

In 2008, University of Nevada Cooperative Extension (Extension) faculty mailed a survey to all agricultural producers who reported at least $1,000 of annual income from agriculture. An electronic version of the survey was developed and offered to individuals with weed management responsibilities in all appropriate federal and state agencies within Nevada.

The 88-question survey targeted nine specific weed management issues and is being used to prioritize the most important educational and research programs for Extension faculty. The results can also be used by other entities charged with weed management to prioritize their activities.

The specific methodologies used for the original survey and analysis are available in Extension Special Publication SP-10-03. Additional statistical analysis was completed to determine if the responses from Churchill County’s agricultural producers differed significantly from Nevada’s agricultural producers and the public lands weed mangers’ responses. The results of this analysis are presented in a series of five fact sheets including the following themes: 1) problem weeds, the approaches and methods used for their control, 2) problems and obstacles to weed management, 3) the spread, prevention and detection of weeds, 4) herbicides and the criteria used for their selection and timing of use; and 5) priority research and outreach programs.

Results and Discussion

Spread of Weeds

Churchill County and Nevada agricultural producers’ rankings were not significantly different when ranking the sources of weeds. However, both groups did differ significantly from the rankings of public land managers (Table 1). The agricultural producers ranked “waterways” as the primary source of weeds to their property. This was followed by “neighbor’s property,” and “roads, railways or utility corridors.” Public land managers ranked “roads, railways or utility corridors” first, and “vehicles or equipment” as the second most important source of weeds. “Waterways” were ranked third by the public land managers in Nevada. These responses are not surprising when considering the differences in size, proximity to neighbors and the prevalence of private land adjacent to waterways in Nevada between lands managed by public land managers and agricultural producers.

All respondents ranked “livestock” in the middle as a source of weeds while “wildlife” was ranked near the bottom by all three. As expected, “visitors or recreational land users” was the lowest-ranked source by the agricultural producers and tied for fifth with “livestock” by the public land managers. “Contaminated products” was cited by both agricultural respondent groups as more important than the public land managers, likely because many public lands have requirements in place for weed-free hay.

Methods of Weed Prevention

As with the sources of weed spread, both agricultural groups were in agreement concerning the best methods to prevent weeds from becoming established. Their overall rankings differed significantly from those of public lands mangers. However, all three groups classified “control new weeds immediately” and “scout for new weed infestations” as the top two most important weed prevention techniques (Table 2). Nevada and Churchill County agricultural producers listed “work to control weeds on neighbors property” as the third most important weed prevention technique. As “neighbor’s property” was previously listed as a significant source of weed infestation by these agricultural producers, this response would be expected. Public land managers listed this method near the bottom, reflecting their low rating of “neighbor’s property” as a source of weeds. The “use of weed-free hay, straw, seed or fill material” and “clean equipment or vehicles contaminated with weed seed” was ranked similarly by all three groups and placed these methods in the middle of the rankings.

Public land managers listed “employee or co-worker awareness of weed spread” as the third most important technique, with agricultural respondents ranking it sixth in the list of priorities. Given the size of public land agencies and short tenure of many of their employees, this response appears reasonable. Interestingly, all groups listed “quarantine grazing animals” as the least important method of weed prevention. The authors speculate that none of the responding groups has experienced problems with grazing animals spreading weeds. Therefore, even though it is a documented problem in other areas, the respondents to this survey rated it very low in priority.

Methods of Weed Detection

When asked “how do you scout for new weed infestations” Nevada and Churchill County agricultural producers did not differ significantly in their rankings. Their priorities were again significantly different than Nevada public land managers' rankings. “Casual scouting” was ranked as the first and second most important method of weed detection by the Nevada and Churchill County agricultural producers respectively. Nevada public land managers ranked this technique fourth (Table 3.) There was general agreement between all respondents that “monitor high risk areas (roads, waterways, etc.)” and “scout using farm/ranch staff/agencies employees” were important techniques. These methods were listed in the top three by all the respondents.

The use of “GPS or GIS technology” was ranked high (third) by the public land managers but no higher than sixth by the agricultural producers. This is thought to represent the wider use of these techniques in a weed management program by the public land management employees. “Formal scouting (use transects or zig-zag pattern)” and “scout using a professional consultant or technician” were ranked in the middle of the priority list by all groups responding to the survey. This may represent the lack of resources dedicated to hiring professionals and lack of time to complete formal inventories by any of the groups surveyed (Creech ET. AL. 2008) The least important technique to detect weeds was “counts using volunteers” (recreationists or visitors).” This is readily understandable for private agricultural producers who rarely use volunteers for any of their required tasks. However, public land managers frequently use volunteers for other land management tasks. It is theorized that the increased level of training required (plant identification, use of GPS, GIS etc.) is a limiting factor. However, with the massive amounts of land controlled by public land managers in Nevada, this technique may be worthy of future efforts by this group.

Additional Resources

Analytical Software. 2008. Statistix 9. User’s Manual. Analytical Software. Tallahassee, FL. 454 p.

Creech, E., L. Singletary, J. Davison, L. Blecker, and B. Schultz. 2010. Nevada’s 2008 Weed Management Extension Program Needs Assessment. University of Nevada Cooperative Extension Special Publication 10-03.

Duncan, C.L. and J.K. Clark (eds). 2005. Invasive Plants of Range and Wildlands and their Environmental, Economic and Societal Impacts. Weed Science Society of America. Lawrence, Kansas. 222 p.

Harris, T.R., and A.K Kerna 2009. An Economic Description of the Agricultural Sectors in Churchill County. University Center for Economic Development. University of Nevada, Reno. Department of Resource Economics Technical Report UCED 2009/10-01. 22 p.

Singletary, L. and M. Smith. 2006. Nevada Agriculture Producer Research and Education Needs: Results of 2006 Statewide Needs Assessment. University of Nevada Cooperative Extension Educational Bulletin 06-02. 118 p.

USDA. 2009. 2007 Census of Agriculture. Nevada State and County Data. Volume 1. Geographic Area Series. Part 28. USDA National Agricultural Statistics Service. Washington, DC.

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