Important seed-borne fungal diseases of rice, detection methods and control
1987
Kauraw, L.P. (Central Rice Research Inst., Orissa (India). Div. of Plant Pathology)
The important seed-borne pathogens of rice are Pyricularia oryzae, Drechslera oryzae, Fusarium moniliforme, Alternaria padwickii, Ephelis oryzae, Tilletia barclayana and Ustilaginoidea virens. The percentage of infection varies from sample to sample, variety to variety and locality to locality with the environmental conditions. The different detection methods studied were blotter, agar plate, soaking of blotters in 0.1 % solution of 2,4-D, guaiacol agar method, test tube seedling method, and soaking of seeds in 0.2 percent solution of sodium hydroxide for 24 h at room temperature of 20-25 deg C then spreading over blotter paper and examining seeds visually for bunt infection. Blotter (untreated seeds) gave better counts of D. oryzae, A. padwickii, Fusarium spp. in varieties CR 1009, CR1011, CR1012 and CR1014. Pre-treatment of seeds with sodium hypochlorite reduces the counts of D. oryzae and A. padwickii. A. padwickii developed much on agar than blotter. Soaking in 0.1% 2,4-D reduce infection percentages. Guaiacol agar method was found more sensitive than the blotter method for D. oryzae and less sensitive for A. padwickii. Pyricularia oryzae can be detected by blotter and guaiacol agar method but infection percent was very low. Test tube seedlings method is good for studying the seed transmission of seed-borne diseases. Dithane M-45, Bavistin, Captan, Thiride-75, Foltaf, Vitavax and hot water treatment reduced the seed-borne infection with different seed-borne infection, but there is an urgent need of development of seed certification standards for different seed-borne diseases of rice where chemicals are not the final answers and also need more sensitive methods of detection which can be utilized for quarantine purposes.
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