Distribution of black shank disease on Temanggung tobacco and environmental factors affecting disease development

Temanggung tobacco recognized for its aromatic character and high-nicotine content is a main component of clove cigarette. Currently, it only fulfils 30% of market requests. A major issue is low productivity caused by land fertility degradation and pathogens invasion such as Phytophthora nicotianae, the causal agent of black shank disease. This research aimed to determine the incidence level and distribution of the disease within tobacco plantation in Temanggung. A survey was conducted on 53 locations determined by a land system method. The incidence of black shank was recorded for each location as well as soil samples were also taken to identify soil nutrient contents. The results revealed that black shank was found at various incidence levels in several sampling points, especially in the paddy land. In dry land, none of black shank was found. In contrast, in paddy land black shank incidence reached up to 44%. It indicated that environmental condition influenced development of black shank. C-organic has a negative correlation with black shank incidence. High black shank incidence took place in low C-organic areas. C-organic has an important effect on the improvement of physical and chemical structure of soil characters as well as the equilibrium of soil microbes.