Biological Characteristics and Screening of Fungicides of the Pathogen Fungi of Saw Palmetto Leaf Spot in the Seeding Stage
Biological characters of Calonectria pteridis which causes leaf spot on Saw Palmetto were determined in the study. The results indicated that the optimal temperature for mycelium growth was 28-30 ℃, and the optimal pH was 5.0-6.0. The optimal temperature for conidium germination was 28 ℃, and the optimal pH was 5.5. The order of carbon sources utilization against C. pteridis was: D-xylose, D-fructose, D-glucose, D-sorbitol, D-lactose,D-maltose and inositol, while the ammonium oxalate was the best nitrogen source for mycelium growth. But there is no significant impact of carbon source and nitrogen source on conidium germination. Inhibition activity of 11 common fungicides against C. pteridis was also detected. According to the results, the best inhibition activities were gained by 50% carbendazim and 70% thiophanate-methyl while their EC50 values was 0.4864 and 2.958 9 mg/L,respectively. In contrast 80% zineb WP and 15% triadimefon EC was 130.160 3 and 159.737 9 mg/L, which showed the worst inhibition activities to the pathogen.