The Relation Between Technologies for Late Blight (Phytophthora Infestans) and the Yield Components (Biomass) of Different Potato Varieties

Abstract

Phytophthora infestans, the causal agent of late blight, is a major threat to potato crop all over the world. Fungicides play a crucial role in the integrated control of late blight. Variety choice is dictated by end users who demand cultivars with specific agronomic characters and these are difficult to combine with late blight resistance. The main aim of this research was to test the influence of two different densities (53300 plants/ha and 44400 plants/ha) and two different late blight control technologies (using only contact fungicides - TECH1 and alternative systemic and contact fungicides - TECH2) on the biomass of three highly cultivated varieties (Riviera, Christian and Roclas). The potato canopy of different varieties present large difference regarding stem length and leaf number, shoot and tubers weight in response to the applied technologies. In 2014 conditions, the total biomass of the varieties and combinations of treatments studied did not differ significantly. In 2015 and 2016 conditions, the varieties were differentiated both by the amount of biomass accumulate on July 1-4 and by the statistical differentiation of the variants within the varieties. The studied densities had significant effects on plant biomass accumulations at the beginning of July. In all years, at the beginning of July, due to the earliness and sensitivity to late blight, the green mass in Riviera variety was significantly lower, compared to the green mass in the middle early varieties Roclas and Christian.