FOSETYL-AL (ALIETTE®), A PLANT DEFENSE ENHANCER WITH GOOD EFFICACY ON BACTERIA AND ON ASCOMYCETES IN APPLES AND PEARS

Fosetyl-Al (FEA) (Aliette®, Bayer CropScience, Monheim, Germany) is a well-known fungicide of the chemical family of metallic mono-ethyl phosphonates, registered in the 1970s. Its antifungal effect on oomycetes can be partly explained by a direct effect on the inhibition of the growth of mycelium (e.g., Plasmopara spp.) by competing for the assimilation of phosphates. Its efficacy is increased by an indirect effect of enhancing natural plant defences via release of ethylphosphonate inside the plant tissue, triggering salicylic acid, jasmonic acid and ethylene pathways. In pome fruit, fosetyl-Al exerts interesting activity against bacteria through reduced host susceptibility against the bacteria Erwinia amylovora and Pseudomonas syringae. It additionally promotes intrinsic flower bud quality and the sink strength potential of flower clusters and may support the plant in overcoming abiotic stress. Evidence has been given that the Plant Defense Enhancement (PDE) effect of fosetyl-Al intensifies the plant immune response against a broad number of ascomycetes such as Stemphylium vesicarium, Venturia inaequalis, Alternaria spp. and Podosphaera leucotricha. Fosetyl-Al offers remarkable persistency against the epiphytic growing S. vesicarium fungus in ‘Conference’ (Pyrus communis L.) pears and reduces the conidial infections of V. inaequalis on newly formed leaves. This potential makes fosetyl-Al an interesting partner in the overall disease control strategy in pears and other crops. Through its PDE effect, fosetyl-Al offers support to the efficacy of approved fungicides, used specifically against these main pathogens in pome fruit.