1. USDA‐ARSTropical Agriculture Res. Stn. (TARS)2200 P. A. Campos Ave., Suite 201MayagüezPR00680‐5470
2. Dep. of Agro‐Environmental SciencesUniv. of Puerto Rico, Recinto Universitario de MayagüezCall Box 9000MayagüezPR00681‐9000
3. Colorado State Univ.Dep. of Soil and Crop SciencesC‐113 Plant Science BuildingFort CollinsCO80523