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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #228542
Title: MEDUSAHEAD OUTPERFORMS SQUIRRETAIL

Author
item Mangold, Jane
item YOUNG, KERT - BRIGHAM YOUNG UNIVERSITY

Submitted to: Extension Reports
Publication Type: Experiment Station
Publication Acceptance Date: 5/1/2008
Publication Date: 6/1/2008
Citation: Mangold, J.M., Young, K. 2008. Medusahead outperforms squirretail. Extension Reports. Range Field Day 2008 Progress Report. Oregon State University Agricultural Experiment Station, Special Report 1085. Burns, OR. pp. 35-42.

Interpretive Summary: Understanding the ecological processes fostering invasion and dominance by medusahead is central to its management. The objectives of this study were 1) to quantify and compare interference between medusahead and squirreltail under different concentrations of soil N and P and 2) to compare growth rates of medusahead and squirreltail. We grew medusahead and squirreltail in an addition series in a greenhouse and applied one of four nutrient treatments weekly: 1) low nitrogen (N) low phosphorus (P) (no N or P added), 2) low N high P, 3) high N low P, and 4) high N high P. After 70 days density and biomass by species were sampled. We also grew individual medusahead and squirreltail plants in control soil conditions. Biomass, leaf area, and root length were determined for each species at 14 day intervals over 72 days. Regression models for medusahead and squirreltail suggested N appeared to be playing a much larger role than P in interference between the species. The high N treatment did not increase medusahead’s interference ability relative to squirreltail as we had hypothesized. Medusahead typically imposed a two to seven times stronger influence on interference relationships than squirreltail. Medusahead accumulated biomass, leaf area, and root length twice as fast as squirreltail. Results from our study suggest that medusahead seedlings will likely dominate over squirreltail seedlings. To restore squirreltail to medusahead-infested rangeland, medusahead densities should be reduced with integrated weed management strategies. On medusahead-free rangeland, prevention and early detection and eradication programs are critical.

Technical Abstract: Understanding the ecological processes fostering invasion and dominance by medusahead is central to its management. The objectives of this study were 1) to quantify and compare interference between medusahead and squirreltail under different concentrations of soil N and P and 2) to compare growth rates of medusahead and squirreltail. We grew medusahead and squirreltail in an addition series in a greenhouse and applied one of four nutrient treatments weekly: 1) low nitrogen (N) low phosphorus (P) (no N or P added), 2) low N high P, 3) high N low P, and 4) high N high P. After 70 days density and biomass by species were sampled. We also grew individual medusahead and squirreltail plants in control soil conditions. Biomass, leaf area, and root length were determined for each species at 14 day intervals over 72 days. Regression models for medusahead and squirreltail suggested N appeared to be playing a much larger role than P in interference between the species. The high N treatment did not increase medusahead’s interference ability relative to squirreltail as we had hypothesized. Medusahead typically imposed a two to seven times stronger influence on interference relationships than squirreltail. Medusahead accumulated biomass, leaf area, and root length twice as fast as squirreltail. Results from our study suggest that medusahead seedlings will likely dominate over squirreltail seedlings. To restore squirreltail to medusahead-infested rangeland, medusahead densities should be reduced with integrated weed management strategies. On medusahead-free rangeland, prevention and early detection and eradication programs are critical.