The first part of the second paragraph of the introduction in mppol/1996/1209ballance should read:

"Isolates of P. tritici-repentis have been classified into four pathotypes based on the ability of member isolates to induce, on a wheat differential set, necrosis and chlorosis [pathotype 1, (nec+ chl+)], necrosis only [pathotype 2, (nec+chl-)], and chlorosis only [pathotype 3, nec- chl+)] (Lamari & Bernier 1989b). Isolates from pathotype 4 do not induce tan necrosis nor chlorosis (nec- chl-) and are considered to be avirulent (Lamari et al. 1990)."

James K M Brown (Co-ordinating Editor), 14 February 1998