Rtd is caused by rice tungro spherical virus rtsv and rice tungro bacilliform virus. Diagnosis of common diseases of rice home irri rice. Depending on the part of the plant affected, the disease is often called leaf blast, rotten neck, or panicle blast. By controlling high blood pressure, quitting smoking, maintaining a healthy diet and by maintaining low cholesterol levels heart diseases can be prevented. Many farmers in south and southeast asia describe rice tungro disease as a cancer disease because of the severe damage it causes and the difficulty of controlling it 7 and 8. Their leaves become yellow or orangeyellow, may also have rustcolored spots.
Tungrovirus is a genus of viruses, in the family caulimoviridae order ortervirales. Dry rot is firm or dry decay, while soft rot is soft, watery decomposition. Bacterial and viral diseases of rice linkedin slideshare. Physical interaction of rtbv orfi with d1 protein of oryza sativa. Top most important plant pathology question answers bank are useful for general agriculture for icar and other jrf, srf, ars, ph. Planting a resistant variety is the simplest and, often, the most cost effective management for diseases. Rf2b was predicted to encode a bzip protein of 329 aa fig. Presence of bacteria in the rice paddy and irrigation. Disease cycle transmission mainly by the leaf hopper vector nephotettix virescens males, females and nymphs of the insect can transmit the disease. Quantitative estimation of seed microflora of rices. The symptoms and severity of this disease depends on these two types of viral. Potential candidate genes for improving rice disease.
Brown and white rice may be consumed after cooking or may be ground into rice flour. Infected plants usually have somewhat fewer tillers than healthy plants. Tungro became a serious problem after the release of highyielding rice cultivars which are short statured and photoinsensitive, have shorter growth duration, and allow rice growers two crops of rice in a year. Pdf on feb 1, 2002, osmat azzam and others published the biology, epidemiology, and management of rice tungro. Tungro is a disease complex associated with rice tungro bacilliform rtbv and spherical. Absence of symptoms at early growth stage of the disease development is one of limitation in the way of tungro management 6. The spots may merge leading to a complete drying of the infected leaf. Heart disease reversal diets south denver cardiology. Symptoms the lesions are usually observed on the leaf sheaths although leaf blades may also be affected.
Complex virus rtbv and rtsv transmitted by green leafhopper nephotettix spp. Tungro is the most serious virus disease of rice and the major constraint to rice production in south and southeast asia. Plant pathology question answers bank for competitive exams. Organism groups see more details ir26, ir62, ir64, ir68305181, utri merah, balimau putih, t11602, t12180 and t12357 was studied during. Pararetroviruses show similarities with retroviruses in molecular organization and replication. Glh retained the ability to acquire rtbv longer than rts\ itself. International conference on integrated plant disease. Rtbv has a long open reading frame that encodes a large polyprotein p3. Southern blot analysis demonstrated that the rice genome contains a single copy of the rf2b gene fig. In rice tungro, rtbv induces most of the symptoms yellowing and reddening of the leaves, stunting of rice plants and rtsv is mainly. Biological control of rice tungro disease rtd springerlink.
Rtbv, or when they acquire rtsv first and then rtbv. Tungro stunts rice plants and changed the leaf colour to shades of yellow or orange. The tungro disease, fairly widespread in this region is caused by the joint infection with two dissimilar viruses. Rice seeds imbibe water at adequate tcmptrsture in the pmence of oxygen yoshida, 198 i. Growth and production of rice encyclopedia of life. Rice tungro disease or yellow orange leaf disease, an important rice disease in asia, is caused by two types of viruses, rice tungro bacilliform vlrus rtbv and rice tungro spherical vlras rtsv. Rice tungro is one of the most destructive viral disease particularly in north eastern and eastern coastal regions of peninsular india. In the philippines, the disease used to attack rice plants in the upland and rainfed rice ecosystem. The spatial distribution spatial distribution subject category. Genetic analysis of tolerance to rice tungro bacilliform. Relations of rice tungro bacilliform and rice tungro. Plant virus disease problems in the developing world. Pdf as the most devastating viral disease of rice in south and southeast asia.
Which one of the following fertilizers contain water soluble p. Pdf the biology, epidemiology, and management of rice tungro. Transmission of rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv to rice and weeds by nephotettix virescens, n. Spot a spot is a localized necrotic or dead area photo 4. Spatial distribution of rice tungro virus on some rice. Compendium of rice diseases and pests, second edition. Since 1984, more women than men have died each year from heart disease. Piercing sucking mouthparts facilitate the delivery of virions into plant cells. Symptoms of tungro include orange yellow coloring of leaves, stunting, reduction in tiller number, and poor panicle emergence.
Rice tungro bacilliform virus rtbv is a reversetranscribing dna virus which, in association with an rna virus, rice tungro spherical virus rtsv, is responsible for rice tungro disease, the most important viral disease of rice in south and southeast asia. The disease is transmitted through spores scattered in the air, affecting rice growing areas that were once free from the disease. From 2005 to 2006, more than 485,000 ha of rice production area in southern vietnam were severely affected by viral diseases seemingly spread by bph, resulting in the loss of 828,000 tons of rice. Rice tungro disease perhaps the most important disease affecting rice is rice tungro disease rtd. Asia describe rice tungro disease as a can cer disease. Beighley encyclopedia of life support systems eolss 2. The term heart disease is often interchanged with the term cardiovascular disease. Rice tungro bacilliform virus rtbv is a pararetrovirus, and a member of the family caulimoviridae in the genus badnavirus. Rice tungro, the most important virus disease of rice in south and southeast asia, is caused by a complex of two viruses, rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv. Grain discolouration of rice has become a serious problem in recent years especially when there is postflowering rain. It may be circular, angular, or irregular in shape.
Rice tungro spherical virus resistance into photoperiod. Properties see more details of rice rice subject category. Rice tungro disease rtd is one of the destructive and prevalent diseases in the tropical region. Rf2b, a rice bzip transcription activator, interacts with. Chaudbary and ghildyal 1969 and ahilja and rkhie f991 incucate that 1 minimum temperaturesfor rice gcmination and development are. Mechanisms of transmission are best understood by considering the routes of virus movement in the aphid circulative versus non. Before 1970s, it was relatively common but minor rice disease in the midsouth riceproducing area of the usa. Rice tungro and tungrolike diseases are distributed in south and southeast. It is a composite disease caused by rice tungro bacilliform virus rtbv and rice tungro spherical virus rtsv 10. Aphids are the most common vector of plant viruses. Rotting is disintegration and decomposition of host tissue photo 3. Rice diseases and pests, description, uses, propagation. Added to asia describe rice tungro disease as a can since the peak that was.
Monocots and family poaceae serve as natural hosts. Unesco eolss sample chapters soils,plant growth and crop production vol. After removal of the rice grain from the chaff, the rice can be used as brown rice or further processed to remove the bran to produce white rice. Tungro virus disease is transmitted by leafhoppers, wherein the most efficient vector is the green leafhopper, nephotettix virescens distant. Tungro disease management in organic basmati rice agropedia. Krishnaveni principal scientist plant pathology breeding elite rice lines resistant against rice tungro virus disease directorate of rice research hyderabad, andhra pradesh. Arsenic induced, unknown physiological disorder white tip see nematodes aphelenchoides besseyi. Transmission of plant viruses by aphid vectors ng 2004. Insects glh were released on infected plants for 24 h to acquire the. Farmers lose an estimated average of 37% of their rice crop to pests and diseases every year. Rice tungro disease rtd consists of a spherical virus rtsv and a bacilliform virus rtbv and the disease is a significant yield constraint in ricegrowing areas of south and southeast asia. In this case of rice tungro disease, viral infection is commonly transmitted by the green leafhopper. Technology identified could reduce the spread of rice.
The disease complex is associated with rice tungro baciliform virus rtbv and rice tungro spherical virus rtsv. The compendium of rice diseases and pests, second edition, is a useful tool for academics and professionals involved with rice crops, including researchers, diagnosticians, extension personnel, crop consultants, farm managers, and growers. Average tungro incidence in monthly planted fields was higher in plots planted in the. Suppression of symptoms of rice tungro virus disease by. Commodities and products see more details tungro virus rtv disease on 9 rice cultivars cultivars subject category. Combining genes that overexpress rf2a and rf2b with genes that provide resistance to the insect vector could generate new rice varieties with significantly improved resistance to rice tungro disease in vulnerable regions in the world. Tungro disease viruses are transmitted from one plant to another by leafhoppers that feed on tungroinfected plants. Rice tungro is a composite disease caused by rice tungro.
This is a leafhopper cicadellidae, nephotettix spp. Insects are the most common of the vectors and, among these, aphids account for the transmission of 50% of the insectvectored viruses brunt et al. It is a valuable tool for the field, lab, or classroom. It generally refers to the conditions that involve narrowed or blocked blood vessels that can lead to a heart attack, chest pain or stroke. Staggered planting under the doublecropping rice systems is the major reason why tungro disease predominated after the 1960s. The biology, epidemiology, and management of rice tungro. Pathogen two morphologically unrelated viruses present in phloem cells.
Rice blast is the worlds most prevalent disease as it reduces yield by 50 to 85%. What it does rice tungro disease is caused by the combination of two viruses, which are transmitted by leafhoppers. Pecky rice kernel spotting feeding injury by rice stink bug, oebalus pugnax. During 19771981, the annual population fluctuation pattern of the vectors nephotettix virescens and n. Blast fungus pyricularia grisea this disease can cause serious losses to susceptible varieties during periods of weather conditions favorable to growth of blast. Integrated management of rice tungro disease in south. Rice tungro disease is caused by the combined action of rice tungro. July 1995 planthopper bph, nilaparvata lugens, which causes damage mainly by sucking the sap of the rice plant although it also carries the virus diseases rice ragged stunt and rice grassy stunt, and secondly, rice tungro virus disease rtvd which is transmitted by the leafhoppers, nephotettix spp. In cytoplasmic male sterile lines a lines where the emergence of the panicles is poor, the incidence of sheath rot is very high.
Rice tungro disease stunting and reduced tillering. They are mainly caused by bacteria, viruses, or fungi. Rice types and products there are two main types of rice, japonica and indica, differentiated by the area where they are grown and by their traits when cooked. Rice tungro disease is caused by the combination of two viruses, which are transmitted by leafhoppers. Their viral carrier is the green leafhopper, nephotettix virescens. Tungro virus disease of rice has been a serious problem in rice production in south sulawesi, indonesia. Information is given on the geographical distribution in asia. The initial lesions are small, ellipsoid or ovoid, and greenishgray photo. Rice is the most important food crop in india and plays a key role in delivering global food security. The disease is caused by rice tungro virus rtv, which is transmitted by the green leafhopper, nephotettix virescens. Rtbv cannot be transmitted by leafhoppers unless rtsv is present.
P3 contains a putative movement protein mp, the capsid protein cp, the aspartate. Rice technology bulletin series pinoy rice knowledge bank. Diseases caused by fungal and bacterial pathogens like magnaporthe oryzae and xanthomonas oryzae pv. It causes leaf discoloration, stunted growth, reduced tiller numbers and sterile or partly filled grains. Risk assessment for rice planthopper and tungro disease. Plants affected by tungro exhibit stunting and reduced tillering. Beating tungro virus disease in rice riu validated rnrrs output. Aphids are exquisitely designed for their roles as vector. Better understanding of the leafhopper insect that spreads the virus has led to better growing practices, especially late. In major ricegrowing rtbv and rice tungro spherical virus rtsv 4. Up to now, in rice, the modification of the expression of more than 60 genes from diverse origins has shown beneficial effects with respect to disease resistance. A suite of new techniques to tackle the devastating rice losses caused by tungro is now helping smallscale farmers in indonesia, the philippines and india.