Lee, My first seach in Google for "plant immunity" brought up this: http://sciencemag.org/cgi/content/… Science 3 April 2009: Vol. 324. no. 5923, pp. 89 - 91 DOI: 10.1126/science.1170025 Priming in Systemic Plant Immunity Ho Won Jung,1 Timothy J. Tschaplinski,2 Lin Wang,3* Jane Glazebrook,3 Jean T. Greenberg1{dagger} That is a place to start.... Jim Shields ************************************************* Jim Shields USDA Zone 5 Shields Gardens, Ltd. P.O. Box 92 WWW: http://www.shieldsgardens.com/ Westfield, Indiana 46074, USA Tel. ++1-317-867-3344 or toll-free 1-866-449-3344 in USA