Assessment of Avocado as a Potential Alternative Host Plant for Colletotrichunigloensporioides Causing Nutmeg Leaf Fall Disease

Abstract
Nutmeg(Myristicafragrans) is an important Export Agricultural Crop grown in Sri Lanka. It is mainly distributed in Kandy and MataleDistricts. Nutmeg Leaf Fall Disease (NLFD) was reported as an economically important disease in 2004 and Colletotrichumgloeosporioideswas identified as the causal organism of the disease. Avocado, mix cropped with nutmeg in Kandyan home gardens reportedsome diseases with the same causal organism as that causing NLFD. Therefore, the study was conducted to assessthe potential of avocado being an alternative hosttothe causal organism of NLFD and to upgrade the existing Integrated Disease M a na ge me nt pra cti ce s of NL FD. T he c ross i nfe ct i on potentialbyC.g/oeosporioidesisolated fromnutineg leaves and avocado fruits were tested through cross inoculation between healthy avocado fruits and healthy nutmeg seedlings.Pathogenicity was quantified calculatingPercent Disease Index (PDI) and Virulence Index (VI). The results revealed that there is a possible disease causing ability of both crops by each isolated strains of C.gloeosporioidesin both ways. The calculated PDI values were 15% and 55% and VI values were 20.2% and 25.8% for nutmeg and avocado, respectively. Thus, avocado plant was identified as a potential alternative host for the causal organism of NLFD. Therefore, the field sanitation of avocado plants must be recommended as an additional measure, where nutmeg and avocado are grown together to avoid spreading of NLFD as a long term disease management strategy.
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Keywords
Animal Sciences, Agriculture, Animal Production, Animal Production Technology
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