EVALUATION OF POTASSIUM PHOSPHITE TREATMENTS FOR LEMON BROWN ROT MANAGEMENT IN TUCUMAN, ARGENTINA

RAMALLO, ANA C; RAMALLO, J; OLMEDO, GABRIELA M.; CERIONI, LUCIANA; RAPISARDA, VIVIANA A.

Foz do Iguaçu

Congreso; XIII International Citrus Congress; 2016

International Society of Citriculture

Potassium phosphite (Phi-K) is registered in Argentina as fertilizer, although it is widely used in citrus for control Brown Rot (BR) and other Phytophthora diseases in pre- and post-harvest treatments. During 2014, 2015 and 2016 different commercial formulations and concentrations of Phi- K were evaluated both in vitro and in vivo using a local isolate of P. citrophthora. Phi?K in vitro inhibited mycelial growth (EC 50 = 47.9 µg/ml), but did not affect sporangia production, spore mobility or germination in the tested concentrations. A single -30 days before harvest- foliar application presented aBR control of 59.3 and 8.8%, evaluated at 30 and 100 days post application,respectively. A positive correlation dose/control was observed, being Phi-K 8? more effective than 2 and 4 ?. In post-harvest dip treatments Phi-K 2000 µg/ml achieved a pre-infection control of 28.5 % and 25.8 % post infection control. In combination with other fungicides, Phi- K slightly increased control efficacy up to 39.2 % and 36.8 %.This post-harvest treatments control effectiveness increased with time, reaching maximum values of 64.9 and 68.3%, when evaluated at 7 and 14 days after treatment, respectively. No statistical differences were observed between different commercial formulations.