Plants are able to shed organs that are diseased, stressed or at the terminal stage of their development. Shedding takes place at a morphologically distinct site, the abscission zone, in a process that is accelerated by ethylene and retarded by auxin. Associated with cell separation is an increase in the expression of a spectrum of gene products, including hydrolytic enzymes and peptides that protect the exposed fracture surface from pathogenic attack. Key research objectives are the identification of abscission-specific gene promoters and the elucidation of the morphogenetic events that regulate cell differentiation in the abscission zone. Manipulation of both the site and rate of shedding will then become feasible.