AVOID older mildew fungicides when choosing partner products for strobilurin-based programmes, ad-vises disease expert Tom McCabe of University College, Dublin.
New mildew killer quinoxyfen (Fortress) or an effective triazole are better bets than low rate morpholine, he advises. The latter may be cheaper, but mildew insensitivity to such products is already widespread, he notes.
Strobilurin-resistant mildew has not shown cross-resistance to quinoxyfen, stresses John Sellars of Dow AgroSciences.
"We are still investigating the exact biochemical mode of action of quinoxyfen, but we do know that it doesnt correspond to the mode of action displayed by any other known group of fungicides, including morpholines, triazoles and strobilurins." *