Cercospora leaf spot caused by Cercospora beticola is one of the most economically important disease of sugar beet plants. Effect of di-basic potassium phosphate (K2HPO4), ascorbic acid and potassium bicarbonates (KHCO3) against Cercospora leaf spot disease of sugar beet plants under field conditions was evaluated.
In laboratory trial, results indicate that ascorbic acid at concentration of 2 and 3 g/L had no inhibitory effect on the tested fungus while, complete reduction in the linear growth was obtained with KHCO3 at 20 g/L. In field trials, results indicated that the most effective treatments were K2HPO4 at concentration 100 mM and KHCO3 at 20 g/L which reduced Cercospora leaf spot severity more than 70.0 and 76.7%, respectively. Treated sugar beet plants with 50.0mM K2HPO4, 3g/L ascorbic acid, 10 g/L KHCO3 and Fungicides (Ridomil-plus at 2g/L) resulted in reducing Cercospora leaf spot severity more than 50.0%. All treatments significantly increased sugar beet yield. The highest increase was obtained with 100 mM K2HPO4 and 20 g/L KHCO3 which increased sugar beet yield more than 1S.2 and 17.4% and the total soluble solids (TSS) of sugar beet roots by 18.7 and 20.0%, respectively. Chitinase activity was stimulated by all treatments. Highest increase was obtained with K2HPO4 at concentration of 100 mM, KHCO3 at 10 and 20 g/L and ascorbic acid at 3 g/L which increased the chitinase activity more than 113.0%.
It could be suggested that some chemical inducers may be used for controlling Cercospora leaf spot disease of sugar beet plants under field conditions.