Effect of some alternative control compounds to fungicides on sugar beet Cercospora leaf spot under greenhouse conditions.

Cercospora leaf spot (CLS) disease is one of the most important diseases affecting sugar beet production in Egypt; caused by Cercospora beticola Sacc. The sensitivity of five beet cultivars were examined for their CLS infection: "Farida, Oscar Poly, Pleno, Arthos Poly, and Gaselle" under natural infection at Kafr-El Sheik, Egypt. Farida cv. was the most sensitive cultivar and was used for a greenhouse trial. This was conducted at the experimental Farm of the Faculty of Agriculture, Fayoum University, Fayoum, Egypt. Soil was divided into two parts, the 1st part was treated by potassium humate (KH) addition, while the other part had no KH treatments. However, sugar beet plants within the two soil parts were treated with foliar application included ten treatments of four different induced resistant chemicals; zinc-sulphate (ZnS-1 and ZnS-2), ammonium-molybdate (AmMo-1 and AmMo-2), salicylic-acid (SA-1 and SA-2), and calciumsilicate (CaSi-1 and CaSi-2), (concentrations; 6, 12, 0.8, 1.6, 3, 6, 5, and 10 mM, respectively), and two control treatments; fungicide (0.5 m/L) and negative control. All the chemical inducers treatments had recorded a significant decrease in disease severity and incidence (DS and DI) compared to negative control. Fungicide recorded the highest decrease in DS and DI, 7.33 and 23.33, respectively. Followed by CaSi-2, AmMo-2, and SA-2 treatments, where DS estimated data were 11.33, 12, and 13.33%, respectively. No significant differences were observed in growth parameters within foliar and soil treatments. CaSi-1 and fungicide treatments showed the most significant increases in extractable sugar. CaSi, AmMo, and SA treatments could be alternatives to fungicide managing CLS. [ABSTRACT FROM AUTHOR]