THE FUTURE ROLE OF SEED HEALTH IN PLANT PROTECTION IN DEVELOPING COUNTRIES
Department of Studies in Applied Botany, University of Mysore, Mysore, India
The sowing of contaminated or infected seeds for crop production can reduce germination and seedling vigour, and affect yield by transmitting pathogens from seed to plants. The most adverse effect of seedborne pathogens is contamination of previously disease-free areas. Primary infection foci are followed by secondary pathogen dissemination, leading to monocyclic or polycyclic diseases. Blast and brown spot of rice, white tip nematode, earcockle in wheat, bacterial leaf blight of rice, downy mildews, smuts, head mould, seedling rots, anthracnose, halo blight and some viral diseases are the major seedborne diseases and have become significant yield reducers in crops of cereals, oil seed, legumes and vegetables in developing countries. The economic significance of seedborne diseases and the changing global scenario in the light of the GATT and W70 are pressurizing the developing countries to give special attention to seed health testing. Programmes have been developed to manage seedborne diseases by exclusion of the inoculum through statutory, cultural and seed treatments. Trends are emerging for need-based seed treatments, and a shift from chemical treatments to biopesticides. Seed health has been recognized for statutory regulation in plant quarantine, seed quality tests and seed treatment programmes. Seed certification has been suggested as part of an integrated pest management system. Designated seedborne diseases, field standards and seed standards have been fixed for many crops. In this regard, national and international cooperation has been sought for effective seed health and crop protection.
In developing countries, seed pathology is not remaining as an academic discipline, but is also being used as a problem-solving exercise to prevent crop losses due to seedborne diseases. Although there is no legal requirement for seed health testing for some important pathogens as yet, serious consideration is being given to amending the seed act and making testing obligatory.