1. Dep. of Land, Air, and Water Resources Univ. of California Davis CA 95616 USA
2. Dep. of Environmental Sciences Emory Univ. Atlanta GA 30322 USA
3. Agricultural and Natural Resources, Cooperative Extension North Carolina Agricultural and Technical State Univ. Greensboro NC 27420 USA
4. Dep. of Plant and Environmental Science New Mexico State Univ. Las Cruces NM 88003 USA