India is an agricultural country wherein most of the population depends on agriculture. About 70% of the India economy depends on agriculture. Due to environmental changes the crops get heavily affected and characteristics symptoms such as leaf spot, dryness, and colour change and defoliation occurs. This paper discusses the development of automatic detection system using advanced computer technology such as image processing and neural network help to support the farmers in the identification of diseases at an early or initial stage and provide useful information for its control. Automatic detection of plant diseases is a very important research topic as it may prove the benefits in monitoring large fields of crops, and thus automatically detect the symptoms of diseases as soon as they appear on plant leaves. Machine learning based detection and recognition of plant diseases can provide extensive clues to treat the diseases in its very early stages. Comparatively, visually or naked eye identification of plant diseases is quite expensive, inefficient, inaccurate and difficult. Also, it requires the expertise of a well-trained botanist. In this paper, an approach is proposed to find the interactions between the disease causing agents and host plant in relation to overall environment; to identify various diseases in plants and to implement a method for preventing the diseases and preventing management for reducing the losses/ damages caused by diseases so as to prevent diseases on plants for the farmers benefits and to help out pesticide company in predicting the new pesticide solutions.