Spray whole area (good soaking) of the plant with Actiferm. Mix with Guard, a sticker agent, so that the actiferm stays on the leaves and is absorbed by the plant.
Treat soil with Bokashi. This is a dry bran product inoculated with EM microbes which has a long lasting effect in the soil depths. Sprinkle the Bokashi on the soil and rake lightly into top surface so that any leaves that have fallen or will fall are treated.