1. Application of carbendazim, twice at fortnightly intervals commencing from boot leaf stage would be effective.
2. Other products found useful in reducing the sheath rot infection are thiophanate-methyl, ediphenphos, hexaconazole, propiconazole and mancozeb.
3. The hybrids, KRH 2, NSD 2, PA 6444 and Indam 100-003 were found moderately resistant to sheath rot.
1. S. oryzae mainly attacks the uppermost leaf sheaths enclosing the young panicles.
2. The lesions start as oblong or somewhat irregular spots 0.5-1.5 cm long, with brown margins and grey centres, or they may be greyish-brown throughout (Ou, 1985).
Common names of Sheath Rot : Rice sheath rot, Sheath rot.
Distribution and Occurrence of Sheath Rot: Present in Karnataka and widely distributed (Sanne Gowda, 1979).
Causal organism: Sarocladium oryzae .
The young panicles are generally affected, leading to an increase the percentage of chaffy, discolored, and shrivelled grains and a reduction in weight and number of healthy grains.
Control Measures for Narrow Brown Spot include cultural and chemical practices.
Cultural practices, such as the use of potassium and phosphorus fertilizers, and planting of early maturing cultivars early in the growing season, could manage this disease effectively.
Chemical Measures: Spraying of fungicides like Benomyl, Propicanazole, Carbendazim, Propiconazole, and Iprodione, when the disease is observed in the field as effective. Mancozeb 2 1g / lit of water at the time of flag leaf emergence.
1. Distribution and Occurrence of narrow brown spot disease: Present in Karnataka (Sanne-Gowda et al., 1973).
2. Common names of narrow brown spot disease: narrow brown leaf spot, cercospora leaf spot, ear blight.
3. Causal organism : Cercospora janseana
1. Chemicals such as Benomyl, Carbendazim, Quitozene, and Thiophanate-methyl can be used to treat the seeds to eliminate the disease.
2. In the field, spraying of Benomyl, Fentin Acetate, Edifenphos, and Validamycin significantly reduce the incidence of leaf scald.
3. Foliar application of Captafol, Mancozeb, and Copper Oxychloride also reduces the incidence and severity of the fungal disease.
1. The symptoms associated with leaf scald vary according to plant age and stage of growth, cultivar and plant density. Newly developed lesions on the tips or edges of leaf lamina, are approximately 1-2 cm² in area with a grey-green, water-soaked appearance.
1. Common names of Leaf Scald : leaf scald, leaf tip blight, leaf tip dying, brown leaf blight, leaf sheath browning, brown leaf spot, leaf blight.
2. Causal Organism of Leaf Scald: Monographella albescens.
3. The leaf scald disease has been reported worldwide in rice-growing regions and seeds prove as the most important inoculum source.
Control Measures of Brown Leaf Spot disease include use of resistant varieties, Cultural and Chemical control measures.
Varietal resistance: IET 1791 and Amruth varieties were found resistant to brown spot disease. Varietal mixtures can also be used to reduce slow disease spread.
Seed treatment: Carbendazim @ 2 g /kg of seeds or mancozeb @ 4 g / kg of seed.
1. Brown Leaf spot is caused by C. miyabeanus, typically affects the leaves and glumes of the host plant, although seedlings, and the sheaths, stems and grains of adult plants may also be affected.
1. Distribution and Occurrence Brown Leaf Spot: Very common in rice growing regions of Karnataka.
2. Economic Importance Of Brown Leaf Spot: 4- 14 % yield loss has been observed in high yielding varieties
3. Causal organism for Brown Leaf Spot: Helminthosporium oryzae
Control Measures for Sheath blight of Rice include Cultural practices and Chemical control.
1. Sheath blight has assumed the status of economically important disease in paddy, and has become a major constraint to rice production during the last two decades.
2. The disease is prevalent in all rice growing regions especially in South India.
3. Flowering stage, fruiting stage, post-harvest, pre-emergence, seedling stage and vegetative growing stage.
Host plant resistance to Rice Blast disease: Planting resistant varieties is the least expense and safest method of disease control. Rice varieties like Rasi, IET 1791, BR-2655 are some of the blast resistant lines being recommended in Southern dry zone of Karnataka. Varietal mixtures can also be used to reduce slow disease spread.
Leaf blast: On leaves, elliptical or spindle-shaped lesions (0.5-1.5 x 0.3-0.5 cm), with pointed ends and grey or white centers. dark- green to reddish-brown margins, sometimes with a yellow halo.
Under humid conditions, abundant conidia are produced on both sides of the leaf. In cases of severe infection, lesions coalesce, killing the leaves.
1. Common names in English for Rice Blast Disease : rice blast disease, rice rotten neck, rice seedling blight, blast of rice, oval leaf spot of graminea, pitting disease, ryegrass blast, johnson spot.
2. Causal organisam - Pyricularia grisea.
3. Parts affected by Rice Blast disease are mainly inflorescence, leaves, seeds, stems and whole plant.
Symptoms of False Smut
1. Symptoms of the false smut will be seen only after flowering.
2. The pathogen, Ustilaginoidea virens, grows in the ovary and transforms it into large, yellowish and velvety green balls, which become greatly enlarged at later stage.
3. The spore balls are covered by a membrane in the early stages, which bursts on further growth and the loose velvety pseudomorphs become visible.
ADVANCES IN INTEGRATED RICE DI SEASE MANAGEMENT ( Dr. Krishnaveni) DRR
Control of Sheath Rot:
1. Removal of infected stubbles after harvest and adopting optimum plant spacing can reduce the disease.
2. Application of potash at tillering stage is also recommended.
3. Foliar spray of calcium sulphate and zinc sulphate was found to control sheath rot.
4. Apply Carbendazim 50WP@ 1g/l. Other products like Thiophanate-Methyl, Ediphenphos, Hexaconazole, Propiconazole and Mancozeb, also useful in reducing sheath rot.