Three natural substances for use against Alternaria cichorii on selected varieties of endive: antifungal agents, plant strengtheners, or foliar fertilizers?

Abstract

During 2004 and 2005 the activity of sulphur, soya lecithin, and salicylic acid on endive and on the fungus Alternaria cichorii were investigated in a field block experiment. In both years, the plants sprayed five times with soya lecithin or three times with sulphur yearly, were significantly less infected than untreated plants. In 2005, the effect of salicylic acid (five sprays) was also shown to be satisfactory. Compared to the untreated plants, the plants treated with natural substances exhibited higher total mass as well as higher net mass. In both years a significant positive correlation was established between the total mass of the plants and yield loss (r2 = 0.66 in the 2004 soya lecithin treatment, and r2 = 0.62 in the 2005 salicylic acid treatment). In 2005, when the fungus occurred to a higher extent, a lower correlation (r2 = 0.30) was confirmed between yield loss and the extent of infection on the exterior leaves. The variety Eros was the most heavily infected with the fungus in both years, while the varieties Escariol gruner, Pancalieri, Avance, and Palmira showed greater resistance to infection with A. cichorii. The varieties Perfect, Pancalieri, and Avance had the highest net mass, while only the first of them showed the highest total mass.