عکس العمل ارقام جدید چغندرقند پاییزه نسبت به بیماری لکه برگی(Cercospora beticola Sacc) در استان خوزستان

Leaf spot disease is one of the most prevalent and most common leaf diseases in sugar beet, which can greatly reduce yield if not controlled. In the province of Khuzestan, if rainfall occurs in April and May, this disease can be detected as an epidemic. Although crop management can reduce the severity of the disease, the only way to cope with this disease is to use resistant varieties. For this purpose, the response of 32 new cultivars of autumn sugar beet was studied at Safi Abad Agricultural Research Center-Dezful during 2017-18, which was a good condition for the outbreak. Evaluation of the resistance of the cultivars to the disease was carried out according to standard method 1 to 9. This means that plants with leaves that are completely healthy are numbered 1 and plants with leaves completely contaminated by disease gives numbered 9. Six cultivars (18.8%) were infected with severity of infection between of 3.5-4.5, 12 cultivars (37.5%) with severity infection between 6-6.5 and 14 cultivars (43.8%) showed infection between of 7-8.5. The cultivars were classified into three groups: resistant, semi-resistant and sensitive, with the highest percentage of susceptible cultivars. Most of cultivars that are cultivated in the region were in semi-resistant group. Cadillac, Palma and Monodoro cultivars were the most resistant cultivars and Sentinel, Orca, Algar and Granate cultivars were the most susceptible. The results of this study showed that one of the main characteristics for introducing new cultivars for cultivation in Khuzestan and similar areas is resistance to this disease.