Epizootic ulcerative syndrome (EUS) prevention and control measures.
Authors: Nandeesha M 
Published: April 2021

Abstract

In Bangladesh, CARE, an international NGO working in development with agricultural and natural resource management as an important component, operated a project funded by the European Union to test the potential of farmer participatory research as a tool to improve the agricultural productivity of farmers. As part of the project activities, participatory action research groups were formed involving farmers with interest to work on the concept. Farmers were encouraged to identify their own farming problems and, based on the identified problems, farmers were assisted to develop their own strategies to solve their problems. Epizootic ulcerative syndrome (EUS) emerged as an important problem in aquaculture for farmers practicing carp culture. Based on the available information on the subject and in consultation with experts in the subject area, treatment strategies were developed by the farmers to manage this major disease, which occurs during the winter season from October to February. Lime, salt, a combination of lime and salt in a 1:1 ratio, or ash, were identified as potential treatment measures during the first year trials. Farmers agreed to apply lime and salt at the rate of 1 kg decimal-1 (1 decimal = 40 m2) as a primary dose followed by a fortnightly application at half the initial dose until the end of the season. Ash was applied at a higher dose of 3 kg 40 m-2 as a primary dose, followed by half the initial dose until the end of the season. A control group of farmers was also maintained within the Participatory Action Research Groups (PARGs). Farmers were not given any financial support for the purchase of inputs, but they were given technical support. Though all farmers did not follow the periodic application at the agreed level of chemicals, all the farmers had made more than one application. The results obtained at the end of first year with 315 farmers were highly encouraging, with good results obtained from the application of lime, salt, or ash. In addition to disease prevention, increase in fish production was noticed by the farmers as a result of application of these inputs to the pond. Following these initial encouraging results at field level, the Institute of Aquaculture, University of Stirling, UK, provided technical and monetary support to continue the study. The results conducted with another group of 232 farmers during second year confirmed the beneficial effects of lime, salt and ash and proved their popularity. In addition to the above treatments, two new treatments involving application of neem (Azadirachta indica) stems with leaves as well as application of adequate fertilisers to ensure green colour of water were also tried. The results confirmed the efficacy of lime, salt and ash as treatment materials to prevent the disease. Though neem stems were not highly effective, farmers were able to derive some relief, but the application of fertilisers to ensure adequate plankton production gave highly encouraging results. Many of these field results could not be replicated under laboratory conditions. Furthermore, a treatment that was effective in one pond did not have a similar effect in a neighbouring pond. These varied results support the view that individual pond ecology influences the effect of treatments adopted. It is thus advisable that every farmer should experiment with the successful treatments in their own pond environment to evolve suitable procedures. Most interestingly, ash, which is commonly available to most farmers as a non-purchased input, can be effectively used to prevent the disease as well as increase fish pond productivity.