ABSTRACT
Black scurf and stem canker disease cause by the fungal pathogen of Rhizoctonia solani and it is an economical important disease of potatoes in Bangladesh and throughout the world. This study evaluated the black scurf and stem canker disease development in potato and antagonistic activity of Trichoderma spp. against R. solani. The artificial infections were carried out using the inoculums of R. solani. The treatments (%inoculum) were: T1 (0% inoculum), T2 (5% inoculum), T3 (10% inoculum), T4 (20% inoculum), T5 (50% inoculum), and T6 (100% inoculum). The infection of stem canker and black scurf on progeny tubers increased with increase in inoculum levels. The highest disease incidence and severity was found in T6 (100% inocula). T6 showed the maximum black scurf infected tubers (russet, deformed and sclerotia). The lowest germination percentage, plant height and tuber yield were also obtained in the same treatment (100% inocula). Trichoderma spp reduced the growth of R. solani and the highest growth suppression was noted in isolate TM12. According to antagonistic activity, Trichoderma spp. reduced the growth of R. solani but was not able to stop the pathogen development. This finding showed management of this disease or R. solani invasion requires an integrated approach compared to Trichoderma single approach.
A rizoctoniose ou crosta negra causada por Rhizoctonia solani é a mais importante doença nos campos de batata em Bangladesh, bem como em várias regiões do mundo. Este trabalho avaliou o potencial do biocontrole com Trichoderma spp. e sua ação antagonista contra R. solani em batateira. Realizou-se as avaliações do potencial antagonosta usando inoculação artificial de R. solani. Os tratamentos (% de inóculo) foram: T1 (0% de inóculo), T2 (5% ), T3 (10%), T4 (20%), T5 (50%) , e T6 (100% de inóculo). A infecção de rizoctoniose na haste e crosta negra nos tubérculos aumentou proporcionalmente com o aumento do nível de inóculo. A maior incidência e severidade da doença ocorreu no tratamento 6 (100 % de inóculo), o qual apresentou maior quantidade de tubérculos infectados e deformados com escleródios em sua superfície. A menor porcentagem de germinação e produção de tubérculos também foi encontrada no tratamento 6, o qual também apresentou menor altura de planta. Trichoderma spp reduziu o crescimento de R. solani e a maior atividade de supressão do crescimento foi encontrada pelo isolado TM12. Foi detectada a atividade antagonista de Trichoderma spp. em reduzir o crescimento de R. solani, mas este não inibiu o crescimento total do patógeno. Conclui-se que o manejo da rizoctoniose da batateira por colonização de R. solani necessita táticas de manejo integrado em detrimento do uso isolado do manejo ou biocontrole com Trichoderma spp.
Subject(s)
Rhizoctonia , Trichoderma , Solanum tuberosumABSTRACT
Vitiligo is quite prevalent and constitutes a major psychological health problem in Bangladesh. To determine the effects and extent distribution of Vitiligo among the people, we mainly focused on the sociodemographic studies on Vitiligo in Bangladesh. The patients volunteered in this study were randomly selected from the Skin and Venereal disease department of Rajshahi Medical college hospital, Rajshahi, Bangladesh during 2009-2011. In this sociodemographic studies 125 vitiligo patients of different age groups were carried out. Age distribution, Sex incidence, occupation, itching, life living status, food allergy, social problem were studied. In this study, disease incidence was the highest 44% among 11-20 years age group. In case of sex incidence the female patients were 56%, on the other hand, male recorded 44%. The demographic characteristic showed that the students were the highest percentage (48%) suffering with Vitiligo by occupation. Family history was the most important survey in this study. 32% patients said they had prior to family history. The maximum patients had living status of middle class (40%). In this study 24% patient complained about Food allergy and the participant patient also complained the social problem of Vitiligo. Eighty percent patients reported that most of the person avoids them because general people know that Vitiligo is an infectious disease. This study will give the social consciousness about Vitiligo i.e. it is not an infectious disease.