Epidemic DISEASE STUDY IN THE PROVINCE OF CANCER STEM Duku JAMBI
ABSTRACT: Duku (Lansium domesticum Corr.) was one of the important plant commodities in Jambi Province, which it has significant contribution to the regional revenue. However, during 2004 to 2011, the production of duku was significantly decreased around 93.73%, which was caused especially by stem canker. Stem canker has been spreading since 2003 in six regencies in the Jambi Province. The increment of disease intensity from 2004 until 2011 was recorded as 40.53% from a population of 365,729 duku trees. The observation conducted in 2012 showed that the highest intensity of disease was occured in Batanghari regency (61.33%), and the lowest was in Muaro Jambi regency (21.33%). The disease formed clustered distribution; it indicated the causal agent was soil-borne pathogens. The identification result showed that Phytophthora palmivora caused stem canker on duku which was varied on colony type, form, and the size of sporangium. The result showed that P. palmivora isolate Djb1 had higher virulence than P. palmivora isolate Djb2 and P. palmivora isolate Djb3, then it was selected as material for the next experiment. P. palmivora isolate Djb1 has a very close kinship with P. palmivora strain TR_2 isolate durian from Thailand and P. palmivora isolate 176 PC of palmoil from Colombia (homologous 99,93% ), and it was able to infect cultivar Palembang, Purbalingga, Purworejo, Matesih, dan Bantul. The level of infection progress of stem canker was driven by weather, soil physic and chemical properties, population of antagonistic microbes, and mycorrhyza at rhyzosphere. Path analysis explained that weather, expecially soil and air temperature, and air humidity, contributed to the increment of the rate of disease infection, although they were not significantly differed among three months of observations (dry, damp, and wet). At wet and damp months, the increment of disease infection was influenced by the increment of soil temperature and air humidity, and the decrement of air temperature. Meanwhile, volume of rainfall and rainy days indirectly influenced the development of disease. At dry months, the rate of disease infection was influenced by the increment of soil temperature and air humidity. Air temperature, volume of rainfall, and rainy days indirectly influence the development of disease. The low content of organic carbon and copper in soil, and low fertility of soil enhanced the development of disease. Population of antagonistic microbes and mycorrhyza genus Glomus sp. would decrease the intensity of canker disease. The result of glasshouse experiment showed that Trichoderma harzianum could supress the development of canker disease, and if it combined with Glomus sp., it would increase the growth of duku seedling.
