Needs Assessment for Noxious Weeds in Humboldt County: Part 3 of 5 Spread, Detection and Prevention of Weeds

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1 Fact Sheet Needs Assessment for Noxious Weeds in Humboldt County: Part 3 of 5 Spread, Detection and Prevention of Weeds Brad Schultz, Extension Educator, Humboldt County; Earl Creech, Extension Agronomist, Utah State University; and Loretta Singletary, Area Director and Extension Educator, Lyon County Introduction Humboldt County covers 9,658 square miles in north-central Nevada, largely north of Interstate 80. The federal government administers about 81 percent of the land area. Winnemucca is the only incorporated city and most of the county s 18,000 residents live within 20 miles of town, including small acreage developments in Grass Valley and Paradise Hill. Small, widespread, unincorporated agricultural communities include Golconda, Paradise Valley, Orovada, McDermitt, Kings River and Denio. Isolated ranches and farms occur throughout the county. The local economy is heavily dependent upon mining and agriculture, and recreation is widespread on the public lands. There are several large transportation and utility corridors that cross the county. These land uses may facilitate the establishment and spread of noxious and invasive weeds. In 2007, the value of agricultural products sold in Humboldt County was $74.35 million (USDA 2009). Crops were valued at $46.54 million and livestock (mostly beef cattle) at $27.8 million of sales. There were 254 economically reportable farms and ranches on 756,313 acres of farmland. Median farm size was 160 acres, the sixth largest in Nevada. On a nationwide basis, Humboldt County is among the top 2 percent of producers for acres of hay production and potatoes, top 5 percent for acres of field and grass seed crops, and the top 13 percent for the number of cattle and calves. Agriculture has a significant multiplier effect in Humboldt County (Harris et al. 1993). For every dollar of increased livestock sales, total economic activity increases by $2.31. Livestock production has the second highest economic multiplier of the 21 economic sectors measured. Each additional livestock production employee results in 2.9 more employees in other segments of the economy. Every dollar of increased crop sales increases total economic activity in Humboldt County from between $1.78 to $2.08. Each additional crop production employee increases employment in other segments of the economy by 2.3 to 3.5 additional employees. Noxious and invasive weeds have the potential to reduce both crop yield and the amount of forage available to livestock (Duncan and Clark 2005). Substantial reductions in crop and livestock production undoubtedly would reduce the income of agricultural producers and decrease expenditures at local businesses. The agricultural multiplier data strongly suggest that reduced agricultural income would have a substantial negative feedback for Humboldt County s economy. Furthermore, noxious weeds can significantly reduce land values. A classic study of the Brooks Ranch in North Dakota found that after noxious weeds became widely established, sale of the ranch took 13 years and the final price was 60 to 80 percent less per acre than for nearby areas without weeds (Weiser 1997). In 2006, the University of Nevada Cooperative Extension (UNCE) conducted a statewide needs assessment about the general research and education needs of agricultural producers (Singletary and Smith 2006). Weed identification and control methods were a high priority in both Humboldt County (90 percent) and Nevada (83 percent). The 2006 survey, however, was too general to identify the specific 1

2 education and research programs needed to address noxious weed issues. Also, the survey did not address weed issues on public lands, a significant resource for Nevada s livestock industry. These shortcomings prevented UNCE from developing a well-defined, issue-specific education and applied research program for weed management. UNCE addressed this information shortfall in 2008 when it conducted a statewide needs assessment for noxious weeds. The statewide results were published in a UNCE Special Publication in 2010 (Creech et al. 2010). To address noxious and invasive weed issues in Humboldt County, the results are being presented in a series of five fact sheets focused on the following themes: 1) problem weeds and 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. This fact sheet discusses part three of the series: the spread, prevention, and detection of weeds. Also, the results from Humboldt County s agricultural producers are compared with the results from agricultural producers across Nevada and from weed managers who manage Nevada s public lands. Survey Methods A 93-question survey targeted the specific weed management issues faced by Nevada s agricultural producers and public land managers. The survey was sent to all agricultural producers who reported at least $1,000 of annual income from agriculture. The specific methodology employed and initial data analysis is described in detail in the recently published statewide needs assessment (Creech et al. 2010). This paper presents additional data analysis (Kolmogorov-Smirnov Test: Analytical Software 2008) to determine if the distribution of responses was similar for agricultural producers in Humboldt County, agricultural producers across Nevada and weed managers for public lands. For the reported P-values, the smaller the number, the greater the probability the two distributions are different. Results The Kolmogorov-Smirnov test indicates that agricultural producers in Humboldt County and the rest of Nevada may view the sources of weed spread differently (Table 1: P=0.15). Agricultural producers in Humboldt County ranked a neighbor s property as the most important source of weeds, and ranked this source of weeds substantially more important than did Nevada s agricultural producers. Slightly over half of Humboldt County s producers ranked waterways as an important source of weed spread. This was 10 percent less than Nevada s agricultural producers. Transportation and utility corridors and contaminated products were considered an important source of weed spread by about 44 percent of Humboldt County producers, but by even fewer producers across Nevada. Less than one-third of both agricultural producer groups ranked wildlife or recreational users as a source of weed spread. The distribution of responses between both agricultural producer groups and the public land weed managers, for the sources of weed spread, was different (Table 1: P 0.05). Public land weed managers ranked transportation and utility corridors, vehicles or equipment, waterways, visitors or recreation, land users and livestock as much more important sources of weed spread than did either group of agricultural producers. For public land weed managers, only wildlife had a relatively low rating as a source of weed spread. For methods of weed prevention (Table 2), the overall distribution of responses between the two agricultural producer groups was similar (P=0.44). For Humboldt County agricultural producers, the three most important methods of weed prevention are: control new weeds immediately, scout for new infestations and clean contaminated vehicles and equipment. Statewide, agricultural producers ranked cleaning vehicles and equipment much lower. Other techniques ranked lower by statewide producers were using weed free materials (hay, straw, seed, etc.) and ensuring employee awareness of weeds. The distribution of responses between each agricultural producer group and the public land weed managers for methods of weed prevention was different (Table 2: P 0.05). Public land weed managers put a much higher emphasis on scouting for new infestations, cleaning equipment and increasing the awareness of weed spread among their co-workers and land users. 2

3 For methods of weed detection (Table 3), the distribution of responses among both agricultural producer groups was similar (P=1.00), but differences did occur. In Humboldt County, agricultural producers ranked casual scouting for weeds and monitoring high-risk areas about 14 percent higher in importance than did Nevada s agricultural producers. Smaller differences occurred for other detection methods. The distribution of responses between each agricultural producer group and public land weed managers was very different (P=0.00). Public land weed managers generally placed more importance on all methods of weed detection. The exception was casual scouting, which they ranked slightly less important than did agricultural producers in Humboldt County. Discussion and Conclusions In Humboldt County, agricultural producers believe that a neighbor s property is the most important source of weed spread, yet they ranked working to control weeds on their neighbor s property much lower in importance. This same dichotomy occurs with the public land weed managers. They identified a neighbor s property as an important source of weed spread but placed comparatively little importance on controlling those weeds. Successful weed control, at both the farm and regional scales, is unlikely to occur if the primary source of weeds is not addressed. The reasons that two or more neighbors do not address the spread of weeds from one property to another are not clear, but probably are many. They may relate to cost, labor shortages, poor working relationships, different priorities during their respective production cycles, different land use missions, different perceptions about the problem or a lack of large-scale coordination and prioritization. Casual observation suggests the latter is often less of a problem when an area has created an active weed district or a cooperative weed management area to help coordinate weed control efforts and share limited resources. About 50 percent of Humboldt County s agricultural producers ranked waterways, roads, railways or other linear corridors as important sources of weed spread. In contrast, more than 80 percent of Humboldt County s respondents believe these types of high-risk areas should be monitored for weeds. The stated importance for monitoring linear corridors (roads, waterways) strongly suggests that Humboldt County s agricultural producers believe corridors are either a source of weed spread (despite a relatively low rating) or they are expected to become a major source of weed spread. A failure to acknowledge all sources of weeds and treat them equally important is likely to result in less-effective weed control. Waterways, roads and other corridors may not be the initial or primary source of weeds but can be very efficient migration corridors because they are regularly disturbed by human and nonhuman activities or events. The result of regular disturbance is large areas of bare ground which weeds colonize, persist upon and disperse from. Humboldt County agricultural producers readily acknowledge that controlling new weeds immediately after they are found is an important method of weed prevention. Recent work in Humboldt County (Schultz 2009) found that almost all current year seedlings of perennial pepperweed are easily killed with one application of Cimarron Max. This occurs because the seedlings lack the large root systems exhibited by mature plants and there are few buds to produce new plants. Scouting for new weed infestations, however, was ranked about 21 percentage points lower in importance than immediately controlling new weeds. Scouting, however, is one of the best methods to find recent infestations of weeds (i.e., young plants with small root systems and few buds). The data about weed detection (Table 3) suggest that scouting and monitoring are high priorities when sites of potential infestations are easy to visit (e.g., roads) or scouting is part of another task. That is, scouting is considered useful when it does not require additional time or labor for the enterprise. Insufficient labor was identified as is a primary obstacle to weed management (Schultz et al. 2010). The aforementioned information suggests that significant weed control problems may develop in areas which producers visit infrequently and/or when weeds are not visually easy to locate and identify. The latter occurs when population densities are low and/or weeds are decadent and visually absent. There appears to be a need to develop strong early detection and rapid response programs to control initial weed infestations. One approach that needs further development is reasonably 3

4 priced, remote-sensing technologies that can identify new weed populations when most of the weeds are young (i.e., have weakly developed root systems) or the weeds cover very small areas. High-resolution remote sensing probably is the best long-term approach to identify weeds in isolated and infrequently visited areas. Research along these lines has occurred in Paradise Valley and along the Humboldt River for perennial pepperweed, Russian knapweed and salt cedar (McGwire et al. submitted). References Analytical Software Statistix 9. User s Manual. Analytical Software. Tallahassee, FL. 454 p. Creech, E., L. Singletary, J. Davison, L. Blecker, and B. Schultz Nevada s 2008 Weed Management Extension Program Needs Assessment. University of Nevada Cooperative Extension Special Publication Duncan, C.L. and J.K. Clark (eds) 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., T.R. McDiarmid, S.W. Stoddard, W.O. Champney, and D.J. Torell Economic Linkages in the Economy of Humboldt County. University Center for Economic Development. University of Nevada, Reno. Department of Applied Statistics Technical Report UCED p. McGwire, K.G., T.B. Minor, and B.W. Schultz. Submitted. Progressive Discrimination: A Simple and Effective Method for Mapping Individual Hyperspectral Targets. Schultz, B.W Herbicide Effectiveness on Adjacent Populations of Young (Seedling) and Mature Perennial Pepperweed (Lepidium latifolium). Annual International Conference, Society for Range Management. Albuquerque, NM. February. Schultz, B.W., E. Creech, and L. Singletary Needs Assessment for Noxious Weeds in Humboldt County: Part 2 of 5 Problems of and Obstacles to Weed Management. UNCE Fact Sheet p. Singletary, L. and M. Smith Nevada Agriculture Producer Research and Education Needs: Results of 2006 Statewide Needs Assessment. University of Nevada Cooperative Extension Educational Bulletin p. USDA Census of Agriculture. Nevada State and County Data. Volume 1. Geographic Area Series. Part 28. USDA National Agricultural Statistics Service. Washington, DC. Weiser, C Economic Effects on Invasive Weeds on Land Values (from an Agricultural Banker's Standpoint). In: Exotic Pests of Eastern Forests, Conference Proceedings - April 8-10, 1997, Nashville, TN. Available at: ml The University of Nevada, Reno is an Equal Opportunity/Affirmative Action employer and does not discriminate on the basis of race, color, religion, sex, age, creed, national origin, veteran status, physical or mental disability, or sexual orientation in any program or activity it conducts. The University of Nevada employs only United States citizens and aliens lawfully authorized to work in the United States. Copyright 2010 University of Nevada Cooperative Extension 4

5 Table 1. Sources of weed spread onto lands managed by Nevada agricultural producers (n=746), Humboldt County agricultural producers (n=56) and public land weed managers (n=52) in Nevada. The values are the percentage of respondents who indicated moderate to high importance. Items are sorted in order of decreasing importance to agricultural producers. Sources of weed spread Waterways (streams, irrigation ditches, canals, etc.) Nevada s agricultural producers Rank importance (%) Humboldt County agricultural producers Rank importance (%) Rank Public land weed managers importance (%) Neighbor s property (public or private lands) Roads, railways or utility corridors Contaminated products (hay, straw, seed, fill material, etc.) Livestock (cattle, horses, etc.) Vehicles or equipment Wildlife Visitors or recreational land-users

6 Table 2. Methods of weed prevention on lands managed by Nevada s agricultural producers (n=746), Humboldt County s agricultural producers (n=56) and public land weed managers (n=52) in Nevada. The values represent the percentage of respondents who indicated moderate to high importance. Items are sorted in order of decreasing importance to agricultural producers. Methods of weed prevention Nevada agricultural producers Humboldt County agricultural producers Public land weed managers Control new weeds immediately Scout for new weed infestations Work to control weeds on neighbor s property Use weed-free hay, straw, seed or fill material Clean equipment or vehicles contaminated with weed seed Employee or co-worker awareness of weed spread Visitor or land-user awareness of weed spread Quarantine grazing animals Table 3. Methods of weed detection on lands managed by Nevada s agricultural producers (n=746), Humboldt County s agricultural producers (n=56) and public land weed managers (n=52) in Nevada. The values represent the percentage of respondents who indicated moderate or high importance. Items are sorted in order of decreasing importance to agricultural producers. Methods of weed detection Nevada agricultural producers Humboldt County agricultural producers Public land weed managers Casual scouting (scout while doing other tasks) Monitor high-risk areas (roads, waterways, etc.) Scout using farm/ranch staff/agencies employees Scout using a professional consultant or technician Formal scouting (use transects or zig-zag pattern) Use GPS or GIS technology Count using volunteers (recreationists or visitors)