1. Dep. of Plant Biol. and Pathology, 59 Dudley Rd., Foran Hall Cook College New Brunswick NJ 08901–8520
2. Dep. of Plant Sci. Univ. of Delaware Newark DE 19717–1303
3. Dep. of Crop and Soil Sci. 116 Agric. Sci. Bldg. University Park PA 16082
4. Nat. Resour. Sci. and Landscape Architecture Univ. of Maryland 214 H J Patterson Hall College Park MD 20742
5. Dep. of Plant and Soil Sci. Univ. of Massachusetts Amherst MA 01003
6. Potash and Phosphate Inst. 18 Maplewood Drive Guelph ON Canada N1G 1L8
7. Rutgers Coop. Ext. of Burlington County 49 Rancocas St. Mount Holly NJ 08060–1317