ABSTRACT
The prevention of the pathogen from entering the host or checking the further development in already infected plants by the application of chemicals is called protection and the chemicals used are called protectants. Many fungicides have been developed for purpose of managing crop diseases which may be used as sprays, dusts, paints, pastes, fumigants, etc. Copper, mercury, zinc, tin and nickel are some of the metals used as base for inorganic and organic fungicides. Sulphur is probably the oldest chemical used in plant disease management for the control of powdery mildews and can be classified as inorganic sulphur and organic sulphur. Metabolites of microorganisms, which in very low or dilute concentration have the capacity to inhibit the growth or destroy other microorganisms. Most of the antibiotics are the products of actinomycetes. Few of them are produced by fungi and bacteria. Antibiotics belonging to this group are produced by many species of Streptomyces. This group includes Terramycin or Oxymicin.
