Intensity of leaf spot and rough bark diseases in cinnamon accessions collected from major cinnamon growing areas of Sri Lanka

Abstract

Leaf spot and rough bark diseases are of high concern among cinnamon growers in Sri Lanka due to potential yield losses. Comprehensive information on distribution and intensity of the above diseases is not available in Sri Lanka. During this study, disease assessment keys were developed for leaf spot and rough bark diseases with subjective scales, which could be useful in assessing the severity of the two diseases. Two hundred and eighty cinnamon accessions from major cinnamon growing areas of Matara, Galle, Kalutara, Kurunegala, Ratnapura and Humbantota Districts were used to determine the intensities of the above diseases. All the districts showed a high level of leaf spot disease severity, where 23.81 % accessions from Galle and 17.14 % accessions from Kalutara districts exhibited the leaf spot disease severity scale of 6. Moreover, 60 % accessions from Kurunegala and 45.71 % accessions from Kalutara districts showed the leaf spot disease severity scale of 5. According to the study on rough bark disease severity, none of the major cinnamon growing areas is at a high risk of rough bark disease. However, the present study indicates the initiation and progression of rough bark disease in the six districts, where Matara district showed considerable levels of infection having 17.39 %, 11.59 %, 5.80 % and 4.35 % of accessions with disease severity scales 2, 3, 4 and 5, respectively. The estimates of the two disease severities explain the present scenario of extent of the two diseases across major cinnamon growing areas in the country.