ABSTRACT
A successful infection will lead to the development of visible symptoms of disease or signs of the pathogen itself. Symptoms and signs may be found on all parts of a plant (i.e. roots, stems, leaves or flowers) and on the seeds and fruits that the plant produces. Plant disease are classified on the basis of various parameters, based on appearance of symptoms, following terms are used to define it. The common characteristic of non-infectious diseases of plants is that they are caused by the lack or excess of something (temperature, soil moisture, soil nutrients, light, air and soil pollutants, air humidity, soil structure and pH) that supports life. Non-infectious plant diseases occur in the absence of pathogens, and cannot, therefore, be transmitted from diseased to healthy plants. The pathogen is dominant over the host, but the relationship is transitory because the resistance of the host is less initially than it becomes eventually.
