POTENTIAL USE OF RESISTANCE INDUCER SUBSTANCES TO CONTROL Botrytis cinerea ON PEARS IN NORTH-PATAGONIA, ARGENTINA

LUTZ, M.C.; SOSA, M.C.; VERA, L.; BRICEÑO, Y.; CARMONA, M.

Santa Cruz

Simposio; XVII international Btrytis symposium; 2016

Lab. de Fitopatología Frutal y Molecular, FCA Univ. de Chile

In Alto Valle of Río Negro and Neuquén, B. cinerea was reported among the main postharvest pathogens in D´Anjou pears. According to global demands of effective and environmentally friendly strategies, the aims of this study were: 1) to quantify in vitro the inhibition of mycelial growth; 2)to evaluate the potential of resistance inducer substances on pear fruits to control B. cinerea. The effect of the resistance inductors (IsR): 2 potassium phosphite (KPhi) (A: 40% v/v & B: 39.2% v/v), manganese phosphite (MnPhi) (40% v/v) and acibenzolar-S-methyl (ASM) (50% w/w) were tested. Different concentrations of each active ingredient were evaluated in vitro against B. cinerea mycelium growth on PDA-medium. The effect in vivo of each IsR was assessed at commercial doses applied to fruit by immersion for 1 min. Fruits were divided in 3 sets: 1) wounded previous treatment, 2) wounded post treatment and, 3) without wounded. Treated fruits with IsR were incubated 72h at 20°C and inoculated with 10 μL of 104 conidia?mL-1 of pathogen. Fruits were stored 60d in commercial chamber (-1/0°C-95%HR). The incidence (%) and severity (mm) of the pathogen on fruit wounds was evaluated. Natural incidence of postharvest diseases was determined at 90d of storage. Mycelial growth of B. cinerea was 100% inhibited with 400 mg?L-1 of KPhi A and 800 mg?L-1of MnPhi; while, KPhi B and ASM at 1000 mg?L-1inhibited in 65% its growth. Effect of IsR treatments applied on wounds (previous treatment), on the disease incidence showed significative reduction by ASM (16%) and KPhi B (20.3%) in relation to control. On the other hand, the severity average was reduced in 39.6%. The incidence percentage of decay incidence when the fruit was wounded after the induction period was from 65% to 96.6%. The ASM inducer showed significant difference respect to control. MnPhi increased the disease severity by 7.75%. The natural incidence of B. cinerea was controlled by all IsR at 90d of storage. Although more studies are needed, our results indicate that the highest inducer effect would be produced on injured tissue (wounds) of the fruit. KPhi A and MnPhi had a direct effect on fungus, whereas KPhi B and ASM could induce resistance to pears against pathogens.