Control of the Most Destructive Rice Blast Disease by Botanicals
A report of the “Mysterious disease affects paddy cultivation in Ganjam (district of Odisha)” appeared in “The Times of India” on 22 August 2002. A team of scientists from NRRI visited along with the State Government Agricultural Officials and observed the occurrence of severe epidemic, caused by the fungal pathogen Pyricularia grisea in the Gajapati (Chhatrapur), Ganjam and Perhampur regions of Odisha. The epidemic caused serious damage to the rice seedlings in nursery as well as the transplanted crops in vast area of the Districts. The high yielding cultivar, Swarna, grown in about 75% of the total nursery sown area (10,000 ha approx) was suffered the most, leading to 70-100% damage of seedlings. The disease was aggravated by the favourable weather conditions, like scanty rainfall, drought conditions, and the susceptible host coupled with sufficient fungal inoculum load.
The scientists from NRRI demonstrated the effectiveness of botanical extract based technology, developed for the control of rice blast at this Institute. The botanical extracts were prepared from the locally and commonly available leaves of the plants, Aegle marmelos (Bael) or Ocimum sanctum (Tulsi). The method of extract preparation was also explained to the group of the farmers. After learning this extract procedure, they prepared the botanical extract and use as per the scientific recommendations to control this disease. Effective communication was made to appraise the farmers of this technology through the active cooperation by, the state agriculture extension machinery, mass media like TV (ETV), AIR, distribution of pamphlets, leaflets in local language and the group meetings. As a result of this approach, a large number of farmers used this technology and benefited by this technology to control successfully the most destructive rice disease, the blast.
Both the plants, A. marmelos (Bael) and O. sanctum (Tulasi) considered to be the sacred plants are generally available to the farmers and can be grown easily. The extracts from these plants can be easily prepared by farmers themselves and utilized at the time of need. The botanical extract-based technology can thus be deployed as an effective strategy of integrated disease management. These botanical extracts are non-hazardous, environmentally safer, locally available, renewable and easily accessible at the time of need for controlling rice blast disease, as against the synthetic fungicides such as Carbendazim, Ediphenphos etc. which are presently in use.