Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Plants, Soils, and Climate

Committee Chair(s)

Ralph E. Whitesides


Ralph E. Whitesides


DeeVon Bailey


Grant E. Cardon


Bruce Miller


R. Douglas Ramsey


Corey V. Ransom


Eric T. Thacker


Millions are spent managing invasive weeds on public lands each year. Wildland invasive weed treatment bids are based primarily on acreage or hours but can be influenced by variables that increase treatment time and cost. Often neither the agency contracting the treatment nor the contractor has a clear idea of the amount of time that will be involved based on these variables. This makes it difficult to develop an accurate budget or bid for invasive weed control projects. It also limits managers in seeking funding and justifying treatment costs.

A model has been developed that can predict herbicide application time due to four variables, weed canopy cover, slope, land cover, and weed visibility. Other variables were explored.

The “smart” spray wand (SSW) is a new precision tool used to develop this model. The SSW is a spray wand with an integrated GPS and a flow meter for use with any type of spray system. The wand records the GPS location, herbicide flow,application time, and associated data of each treatment spray point. This information provided necessary data for the treatment time model. Weed control total treatment time (TTot) was hypothesized to include both treatment time (Tt) and rest time (Rt). The development and benefits of a wildland weed treatment time model are discussed.

An accurate treatment time model could 1) establish an accurate standard for contractors and land managers, 2) assist in planning and managing limited treatment resources, and 3) justify funding requests and expenditures.

The primary influence of the model is due to weed canopy cover (p=2=0.5607), with smaller impacts by other variables. If canopy cover, slope, land cover, and weed visibility can be obtained for a weed control project, the model can be used.