Diagrammatic scale of severity for postharvest black rot (Ceratocystis paradoxa) in coconut palm fruits

Abstract

ABSTRACT One of the major bottlenecks in the postharvest commercialization of coconut fruits is the black rot disease, caused by the fungus Ceratocystis paradoxa. This disease has been neglected in the main production areas or associated with other coconut diseases. To date, there are no standardized methods for assessing the intensity of such a problem. In this sense, the aim of our study was to prepare and validate a diagrammatic scale to evaluate the disease severity in coconut fruits. We also tested the scale applicability comparing distinct C. paradoxa isolates on inoculated fruits. For such quantification, the fruit longitudinal sectioning was necessary, allowing the visualization of internal symptoms. The proposed scale showed good repeatability and high reproducibility, with absolute errors around 8%, while the coefficient of determination presented an average of 91% with the aid of the scale and of 59% without the scale. In addition, symptom analyses showed that the outer necrosis does not match the internal damage. Therefore, we suggest in this study that the severity estimate of this disease be obtained by using the presented scale.