Essays with Argentina citrus fruits using potassium phosphite show lower levels of control than in other growing areas

Potassium phosphite (Phi-K) is widely used in citrus for?control Brown Rot (BR) and other diseases caused by Phytophthora?spp. in pre- and post-harvest treatments. During?2014, 2015 and 2016 different commercial Phi-K formulations?were evaluated both in vitro and in vivo using a local?isolate of P. citrophthora. Phi-K in vitro inhibited mycelial?growth (EC50= 47.9 ?g mL-1), but did not affect sporangia?production, spore mobility or germination at the tested?concentrations. In field trials, a single foliar application of?0.4% Phi-K before harvest time, reduced BR incidence by?40.7 and 12.8% compared to the control when was evaluated?in artificially inoculated fruit at 30 and 100 days postapplication,?respectively. In post-harvest dip treatments,?2000 ?g mL-1 Phi-K showed a pre-infection BR control of?28.5% and a post-infection control of 25.8%. Effectiveness?of post-harvest treatments increased with time, reaching?maximum control values of 64.9 and 68.3% when was?evaluated at 7 and 14 days after treatment.Phi-K slightly?increased control efficacy in combination with conventional?fungicides. No statistical differences were observed?between different commercial Phi-K formulations. Phi-K?effectiveness in controlling BR presents lower levels than?that observed in other citric production areas.Financial support: PICT2012-2838 and PFIP-ESPRO141/12. Original title and complete list of authors and sourcesEVALUATION OF POTASSIUM PHOSPHITE TREATMENTS?FOR LEMON BROWN ROT MANAGEMENT IN TUCUMAN,?ARGENTINARamallo AC1, Cerioni L1, Olmedo GM1, Ramallo CJ2 &?Rapisarda VA11Instituto de Qu?mica Biol?gica Dr. B. Bloj e INSIBIO?(CONICET, UNT), Argentina; 2Citr?cola S.A., San Miguel,?Tucum?n, Argentinae-mail: jramallo@sa-sanmiguel.comInternational Citrus Congress 2016 Picture, Different degrees of development of?Phytophthora hibernalis?by?Estaci?n Fitopatol?xica do Areeiro, Pontevedra, Spain