Studies on Banded Blight of Rice (Oryza Satival) Caused By Jhanatephorus Cucumeris (Frank) Donk in Chotanagpur
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Date
1994
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Birsa Agricultural University, Ranchi
Abstract
Rice (Oryza sativa L.) suffers fron "banded blight" a very caused by Thanatephorus cucumeris (Frank) destructive disease cau Donk (=Rhizoctonia solani kühn). The characteristic symptoms of the disease was observed on leaf sheath, leaf blade, stem, panicle and spikelets.
The pathogen was isolated, purified and identified by standard method. The pathogen also satisfied Koch's Postulate tests.
Potato dextrose agar (solid) and Kirchoff's (liquid ) media supported maximum mycelial growth and sclerotial production. pH 6.5 was found to be optimum for mycelial growth and sclerotial production in Kirchoff's liquid medium. The pathogen was found to penetrate the host by means of infection cushion and stomatal openings.
All 34 plant species belonging to 7 families were infected during host range studies.45 days old plant were highly susceptible and showed maximum intensity (64.7%) with minimum yield followed by 38 and 60 days old plants. Older plants were resistant to infection Early sowing minimized the disease development and gave good yield. Temperature, humidity and rainfall occurred during July 1st to August 1st were suitable for the maximum disease development.
Out of 23 rice varieties / lines non was found to be resistant against the pathogen. However, BR-9, BR-10, BR-34, IR-36, IR-50, Pankaj and RAU-4845-10 showed moderately resistant reaction. Among different fungitoxicants tested Contaf (0.1%),
Bavistin (0.1%) Bavistin (0.05 %) + Indofil M-45 (0.125%), Kitazin (0.1%) and Blitox-50 (0.2%) completely inhibited the growth of the pathogen in vitro.
Bavistin (0.1%) and Topsin - (0.1%) treated rice seeds gave maximum germination 96.3% and 95.3% and elimination of seed borne infection 97.8% and 94.8%, respectively.
Three spray of Contaf (0.1%) and Bavistin (0.1%) in the field condition gave the best control of the disease along with highest yield. These two fungicides also gave maximum per rupee return ie. Rs. 7.6 and Rs. 3.5, respectively. Next economically best fungicide was Bavistin + Indofil M-45 followed by Topsin -H + Indofil M-45.
In bio-control through fungal antagonists, Gliocladium virens showed maximum inhibition of mycelial growth and sclerotial production of the pathogen followed by Trichoderma harzianum and Trichoderma viride. Nature of mycoparasitism was established in detailed.
Among different plant extracts, Munga roots extract showed maximum inhibition of mycelial growth (55.2%) followed by Pipel (48.2%) and Bhangria (44.9%) leaf extracts. All the plant extracts checked the sclerotial formation completely. except Pipel' and Bhangria leaf extracts in which only a few sclerotia were formed. Among oil cakes tasted, Til cake inhibited maximum mycelial growth (86.3%) followed by Karanj' cake (83.3%) and *Neem* cake (81.9%). Sclerotial production was completely inhibited in all the cakes used.