The research was conducted in Suceava (Romania) during the 2023 growing season and aimed to evaluate the interaction between phytosanitary treatment regimes and genotype response in potato (Solanum tuberosum L.) under late blight (Phytophthora infestans) pressure. Four commercial cultivars (Darilena, Red Lady, Riviera, Temerar) were tested in a 4 × 5 factorial experiment with five treatment schemes applied according to crop phenophases (BBCH 35–55), including systemic, systemic-contact, contact-only programs, and an untreated control. Climatic analysis based on decadal records showed alternating periods of moderate temperature (15–22°C) and high relative humidity (>80%), particularly in June and early July, creating favorable infection conditions. Yield was determined at harvest and fractionated into commercial size classes. ANOVA results indicated no significant treatment influence on the smallest tuber fraction (<30 mm), a moderate linear trend for medium-sized tubers (30–55 mm), and a strong significant positive effect of intensive treatments on the largest fraction (>55 mm). Cluster analysis grouped the genotype–treatment combinations into three clusters, reflecting distinct yield structuring under disease pressure. Temerar and Riviera exhibited the highest stability and partial resistance, Red Lady showed intermediate behavior, while Darilena was highly sensitive, with its highest yield obtained even in the untreated variant, suggesting intrinsic but limited resistance expression. The findings demonstrate that phytosanitary strategy and cultivar selection must be jointly optimized to ensure stable marketable yield in temperate-humid potato production systems.

potato, late blight, phytosanitary treatments, yield, genotype response

biology

Presentation: poster