Efficacy of New Fungicide Mixtures in Controlling Phytophthora infestans (Mont.) de Bary in Serbia

Abstract

In order to control the causal agent of late blight on potato, the efficacy of several fungicides was evaluated in four localities in Serbia where a strong epidemic of the target disease was expected. The following materials were tested: Feniks, applied at 3.0 L/ha and 4.0 L/ha (chlorothalonil + potassium phosphite, Luxembourg d.o.o.); Consento, applied at 1.67 L/ha and 2.0 L/ha (fenamidone + propamocarb hydrochloride, Bayer CropScience); and Infinito, applied at 1.2 L/ha and 1.6 L/ha (fluopicolide + propamocarb hydrochloride, Bayer CropScience). Trials were established according to EPPO guideline PP 1/2(3). A complete randomized block design with four replicates per treatment was used in the experiment. Mean percent disease control values were calculated from the evaluations made towards the end of the trials, when differentiation between treatments was most obvious. Data were analysed by one-way completely randomized ANOVA, and means comparison performed by Duncan's test. The infection of untreated control plots ranged from 23.4 to 41.5%. All treatments were effective against P. infestans and significantly reduced disease severity in all experiments, compared with the untreated control. Comparing the fungicide mixtures tested, the higher concentration of Consento was found to demonstrate the highest efficacy in all trials (95.1-97.2%). There was no significant difference between the efficacies of Feniks at higher concentration (89.2-93.8%) and Infinito (90.2-94.3%). Lower concentrations of Feniks (3.0 L/ha) and Infinito (1.2 L/ha) exhibited statistically lower efficacy (82.3-85.5%) than Consento.