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Visually estimating weed cover <br />• Determine the weed species whose cover you want to estimate and the area covered by the weed <br />management objective. For high - priority weed patches, the area would be the patch. If it is a larger area <br />infested by a high - priority weed species, it would be the mapped area where the weed occurs in a weed <br />management unit. <br />• Randomly select a spot to begin to collect cover data. This can be done by overlaying a grid on the <br />aerial photo, or using measuring tapes laid at right angles on the ground, and then using a random <br />number generator to select coordinates. Randomly selected plots can be permanently marked, or new <br />randomly located plots can be selected each time monitoring is performed. This choice will affect the <br />type of statistical analysis used. <br />• At the spot, lay the plot frame on the ground without looking directly at the ground. You do not want to <br />bias the selection of the precise plot location. We recommend using a plot frame that is 2 feet by 4.5 <br />feet because it covers one square yard of ground surface and because rectangular plots are more <br />efficient than other shapes. <br />• Standing at the middle of the long axis of the plot and looking straight down toward the ground, <br />estimate the cover of the target weed species. You may have to move back and forth to obtain a clear <br />view of the entire plot. Estimate weed density according to the following categories: <br />Category Estimated cover of the target Symbol <br />weed species in each plot <br />Absent 0 A <br />Light 1 % - 25% L <br />Moderate 25% - 50% M <br />Heavy 50% - 75% H <br />Extreme 75% - 100% E <br />It is best to record your initial impression of weed cover, rather than spending lots of time deciding which <br />cover category best describes the plot. Record the appropriate symbol (A, L, M, H, or E) on your data <br />sheet. <br />• Repeat this process of randomly selecting sampling locations 29 more times to sample a total of 30 <br />spots, if you will be performing statistical analysis on the data. <br />If a Colorado State Noxious Weed is found during operations and monitoring, weed control <br />measures shall be implemented in accordance with County and State weed control personnel. A <br />complete list of Colorado noxious weeds can be found at <br />www.colorado.gov /cs/ Satellite /Agriculture... /1174084048733. <br />