1. Abacus Concepts, Inc.; 1918 Bonita Ave. Berkeley CA 94704
2. Dep. of Vegetable Crops; Univ. of California; Davis CA 95616
3. Dep. of Environmental Science Policy, and Management; 108 Hilgard Hall, Univ. of California; Berkeley CA 94720
4. Dep. of Plant Pathology and Microbiology, Faculty of Agriculture; P.O. Box 12 Rehovot 76100 Israel