Seed Health Management for Better Productivity - Govind Ballabh ...

(Seed Health Management for Better Productivity)should be established in well designed experiments. The first step is to have a suitable seedhealth assay. But very few methods are thoroughly researched to determine if they are specific ,accurate reproducible, and practical.The next step is to plant seed with different infection level in the field and establish acorrelation with plant infection.For diseases that have no repeating cycle of infection such as seedling infecting smuts,strong correlation between seed infection and field diseases can usually be expected.It is much more difficult to establish inoculum threshold for diseases for which secondaryinfections occur from other inoculum sources.iii. Certification ProgrammeThis programme exists to protect against spread of disease by seeds with in geographicregions. In this programme seed lots must meet certain minimum standards of quality whichincludes specific diseases, before seed can be marketed.This programme uses knowledge of the epidiomiology of the disease that includes laboratoryassays of the seeds and field controls.iv. Phytosanitory certificationThe system has some serous problems, however phytosanitary regulations are determinedby individual countries and often are made on the basis of a poor understanding of the economiclosses that introduction of particular pathogens could potentially incur; minimal knowledge ofrelation ship between tolerances in seed assays to risks of transmission of the pathogen to theplanted crop; and lack of standardized testing protocols.v. GermplasmInternational Agriculture through out the worlds are taking steps to minimize theintroduction and spread of exotic seed borne pathogen by seed exchange.Several international centers have implemented programs to manage seed borne pathogenthrough monitoring pathogens in the seed lots, modification of seed production practices tominimize the infection or transmission of pathogens by seed and use of seed treatment.vi. Seed treatmentChemical, physical and biological seed treatment has dramatically changed in the last 20years. As a result of new fungicide chemistry, advances in biological control and environmentalregulation that have either banned or restricted the use of fungicides. Fungicide seed treatmentremains the most widely used practice and established materials such as captan and thiram stillare the mainstay of seed treatment chemistry. Several systematic fungicides such as metalaxyl,iprodione and triadimenol are being used for management of deep seated infections in seed andsubsequent protection of seedling against infection.Chemical control of seed borne bacteria has limited success, either because of lack ofcontrol of internal inoculum or phytotoxicicity to the seeds. Antibiotics, applied in polyethylene- 42 -