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487:, by vegetative propagation using cuttings from infected plants, and occasionally by mechanical means. Cassava produces its first leaves within 2–3 weeks of planting; these young leaves are then colonized by the viruliferous whiteflies. This is the key infection period for CMD geminiviruses, as they cannot infect older plants. As the genome of the viruses has two components, DNA A and B, that are encapsidated in separate geminate particles, it requires a double inoculation to cause infection.
63:
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protect them from being inoculated by whiteflies, but research shows that the virus is more aggressive in plants infected from contaminated cuttings than by insect vectors. There are also specific varieties that fare better against some viruses than others, so plant resistance is possible. For example, hybrids that are a result of crossing cassava and other species, such as
546:
Control strategies for cassava mosaic disease include sanitation and plant resistance. In this case, sanitation means using cuttings from healthy plants to start with a healthy plot and maintaining that healthy plot by identifying unhealthy plants and immediately removing them. This strategy does not
502:
and travels to the base of the stem and out into the branches. Travel to the branches of the plant is much slower than travel through the stem, so cuttings of branches from infected stems may be free of disease. Some literature has indicated that infection is limited to above-ground tissue, but it is
511:
The severity of cassava mosaic disease is impacted by environmental factors such as light intensity, wind, rainfall, plant density and temperature. Given that the viruses are transmitted by whitefly, the spread of the virus is going to depend largely on the vector. Temperature is the most important
491:
Symptoms appear after a 3-5 week latent period. Adult whiteflies can continue to infect healthy plants 48 hours after initial acquisition of the virus. A single whitefly is sufficient to infect the host; however, successful transmission increases when multiple infected whiteflies feed on the plant.
490:
Generally, whitefly requires 3 hours feeding time to acquire the virus, a latent period of 8 hours, after which it needs 10 minutes to infect the young leaves. There is variation in the literature on this score, however, with other sources citing a 4-hour acquisition time and 4-hour latent period.
422:
and was introduced to Africa in relatively recent times. It is known to be a very drought-tolerant crop with the ability to yield even when planted in poor soils. When cassava was first grown in Africa, it was used for subsidiary purposes though it is now considered to be one of the most important
519:
Whiteflies can fly at speeds up to 0.2 mph, and in high-wind conditions they can move much greater distances in a shorter time, thus increasing rate of virus spread. This wind-dependent spread is reflected in the location of the whitefly in cassava fields, with populations greatest in upwind
595:
CMD was first described in 1894 and is now considered one of the most damaging crop viruses in the world. Annual economic losses in East and
Central Africa are estimated to be between US$ 1.9 billion and $ 2.7 billion. Although cassava is also cultivated in Latin America and South East Asia, the
523:
Virus incidence increases when cassava is growing vigorously. Thus, plant density impacts the spread of the virus, with low-density fields encouraging faster disease propagation than high-density ones. In dry areas, rainfall can be a limiting factor for cassava growth so higher rainfall will be
449:
mosaic of the leaves, leaf distortion, and stunted growth. Leaf stalks have a characteristic S-shape. Infection can be overcome by the plant especially when a rapid onset of symptoms occurs. A slow onset of disease development usually correlates with death of the plant. Besides the conventional
603:
The
Ministry of Agriculture Food Security and Cooperatives of Tanzania recommend uprooting diseased plants once every week by pulling them out by hand. Plants should be carried away from the field and exposed to the sunlight for drying and then burned to kill the viruses.
576:
The
Ministry of Agriculture Food Security and Cooperatives of Tanzania recommend uprooting diseased plants once every week by pulling them out by hand. Plants should be carried away from the field and exposed to the sunlight for drying and then burned to kill the viruses.
532:
type climates, where it is wet and humid most of the year, rapid virus distribution occurred from
November to June, and slow progress occurred from July to September. This timing correlated with higher and lower temperatures. In a study of the disease in the
457:
Though the cassava-infecting geminiviruses causes most of their economic damage in cassava, they are able to infect other plants. The host range depends on the species of virus and most are able to be transmitted and to cause disease on plants of the genera
562:), adjacent to cassava, avoiding planting cassava if neighbouring fields have virus-infected cassava as these could be carried by Whiteflies. Prevention methods also include not planting alternative hosts of the virus vector Whitefly e.g. tomato.
512:
environmental factor controlling the size of the vector population. In the literature, vector-preferred temperature estimates vary from 20 °C to 30 °C to 27 °C to 32 °C but generally high temperatures associated with high
393:
practices as well as the use of conventional resistance breeding. Additionally, vector management and cross-protection help to minimize transmission and symptom development. Though management practices are useful, the viruses’ high rate of
527:
Timing of planting can play an important role in the severity of disease, with cassava planted in March showing a 74% incidence rate of CMV, compared with 4% in August. Seasonal distribution of the virus will vary with the climate. In
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of Africa, maximum rate of disease spread was reached two months after planting. Little to no infection occurs after three months, and variation in spread was due to change in temperature, radiation and population levels of whitefly.
793:
Sseruwagi, P.; Sserubombwe, W.S.; Legg, J.P.; Ndunguru, J.; Thresh, J.M. (2004). "Methods of surveying the incidence and severity of cassava mosaic disease and whitefly vector populations on cassava in Africa: a review".
580:
Most research has been done under unrealistic conditions and so relates only poorly to application in the field. Rare studies under realistic conditions include
Mollard 1987 and Otim-Nape et al 1994.
358:. The first report of cassava mosaic disease (CMD) was from East Africa in 1894. Since then, epidemics have occurred throughout the African continent, resulting in great economic loss and devastating
434:, it is particularly vulnerable to viruses and thus Cassava geminiviruses lead to great economic loss each year. When these infect a host plant, the plant’s defense system is triggered. Plants use
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Fauquet, C. and
Fargette, D. (1990) African Cassava Mosaic Virus: Etiology, Epidemiology, and Control. Laboratoire de Phytovirologie, ORSTOM, Abidjan, Ivory Coast. Plant Disease. 74: 404-411.
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associated with higher incidence of disease. Populations of whitefly will increase with rainfall, but heavy rains may impede whitefly spread and thus decrease incidence of virus.
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Harrison B & Robinson D (1999). Natural genomic and antigenic variation in whitefly-transmitted geminiviruses (begomoviruses). Annual Review of
Phytopathology. 37: 369–398.
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to suppress viral replication, though begomoviruses have evolved a counter-acting suppressor protein against this natural host defense. Because different species of
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Fargette, D. and Thresh, J.M. (1994). The
Ecology of African Cassava Mosaic Geminivirus. In: Bakeman, J.P., Williamson, B. (Eds). Ecology of Plant Pathogens, CABI.
870:
Timmermans, M.C.P., Das, O.P., Messing, J. (1994). Geminivurses and Their Uses as
Extrachromosomal Replicons. Annu. Rev. Plant Physiol. Plant Mol. Biol. 45:79–112.
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food staple crops on the continent. Its production is moving toward an industrialized system in which plant material is used for a variety of products including
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Fargette, D., Jeger, M., Fauquet, C., Fishpool, L.D. (1994). Analysis of
Temporal Disease Progress of African Cassava Mosaic Virus. Phytopathology. 54; 1 91–98.
414:, Family Euphorbiaceae), a tropical tuber crop. Muruwere, Manica Province of Mozambique. The leaves show symptoms of cassava mosaic disease, caused by a virus.
1049:
https://web.archive.org/web/20190223033858/https://www.apsnet.org/edcenter/advanced/topics/EcologyAndEpidemiologyInR/DiseaseProgress/Pages/CassavaMosaic.aspx
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suggests intercropping with cereals and legumes, such as maize or cowpeas, to repel whiteflies and rotate cassava with non-host crops including sorghum.
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After entering the plant through the leaves, the virus remains in the leaf cells for 8 days. As it is a single-stranded DNA virus, it needs to enter the
1013:
736:
Legg J & Thresh J (2000). Cassava mosaic virus disease in East Africa: a dynamic disease in a changing environment. Virus Research. 71: 135–149.
516:, rapid development, and greater longevity in whitefly. Increased light intensity has been shown to increase activity of the whitefly vector.
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produce different variants of this suppressor protein, co-infection by multiple species typically leads to more severe disease symptoms.
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689:
Patil B & Fauquet C (2009). Cassava mosaic geminiviruses: actual knowledge and perspectives. Molecular Plant Pathology. 10: 685–701.
374:. This resistance worked as an effective control for many years. However, in the late 20th century, a more virulent virus broke out in
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geminiviruses infecting it are only found in Africa and the Indian sub-continent. This has been mainly attributed to the inability of
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Thresh, JM & Cooter, T.J. (2005). Strategies for controlling Cassava Mosaic Disease in Africa. Plant Pathology. 54: 587–614.
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and co-infection capabilities have caused CMD to be one of the most detrimental diseases affecting food supply in Africa.
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Initially following infection of a cassava geminivirus in cassava, systemic symptoms develop. These symptoms include
333:, SLCMV), though cassava is cultivated in Latin America as well as Southeast Asia. Nine species of cassava-infecting
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Prevention methods of CMV spread include, avoiding planting alternative hosts of the virus, such as castor bean (
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Legg J & Fauquet C (2004). Cassava mosaic geminiviruses in Africa. Plant Molecular Biology. 56: 585–599.
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analysis. This number is likely to grow due to a high rate of natural transformation associated with CMV.
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in the world. In recent times, cassava production has turned from subsistence to commercial production.
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and quickly spread to East and Central Africa. This highly virulent strain was later discovered to be a
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Bock K & Woods R (1983). The etiology of African cassava mosaic disease. Plant Dis. 67: 994–995.
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Plantwise Factsheets for Farmers: Control of cassava mosaic disease by uprooting
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plants; these have thus far only been reported from Africa. Related species of viruses (
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is the common name used to refer to any of eleven different species of plant pathogenic
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Thresh J (2006). Control of tropical plant virus diseases. Virus Research. 67:245–295.
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Mostly grown as a food source in Africa, cassava is the third largest source of
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of the leaf cells to replicate. After this initial period, the virus enters the
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Cassava geminiviruses are transmitted in a persistent manner by the whitefly
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996:"Plantwise Knowledge Bank | Control of cassava mosaic disease by uprooting"
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1055:"ICTVdB Virus Description - 00.029.0.03.004. African cassava mosaic virus"
1038:"ICTVdB Virus Description - 00.029.0.03.004. African cassava mosaic virus"
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Thurston, H.D. Tropical Plant Diseases. St. Paul: APS press, 1998.
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Cassava Mosaic Disease is currently spreading across SE Asia.
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Artistic rendering of symptoms of a cassava mosaic virus in
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to colonize cassava effectively in this part of the world.
555:, have been shown to have considerable resistance to CMV.
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was first shown to affect symptomology by Mollard 1987.
362:. In 1971, a resistant line of cassava, the predominant
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have been identified between Africa and India based on
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327:, ICMV) are found in India and neighbouring islands (
752:"Plantwise Knowledge Bank | Cassava mosaic disease"
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198:East African cassava mosaic Cameroon virus
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758:. Pest Management Decision Guides. 2018.
306:(SACMV) are distinct species of circular
259:included but traditionally excluded taxa
177:African cassava mosaic Burkina Faso virus
212:East African cassava mosaic Malawi virus
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205:East African cassava mosaic Kenya virus
503:not clear why this would be the case.
348:The viruses are members of the family
520:borders and lowest within the field.
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1081:Viral plant pathogens and diseases
303:South African cassava mosaic virus
240:South African cassava mosaic virus
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389:CMD is primarily managed through
297:East African cassava mosaic virus
219:East African cassava mosaic virus
18:East African cassava mosaic virus
643:work. Licensed under CC-BY-SA (
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621:work. Licensed under CC-BY-SA (
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61:
1016:from the original on 2020-06-04
772:from the original on 2020-06-04
330:Sri Lankan cassava mosaic virus
247:Sri Lankan cassava mosaic virus
191:Cassava mosaic Madagascar virus
814:10.1016/j.virusres.2003.12.021
477:Causal agent and disease cycle
410:The inflorescence of cassava (
1:
265:All the 398 other species of
1000:Plantwiseplus Knowledge Bank
756:Plantwiseplus Knowledge Bank
645:license statement/permission
623:license statement/permission
291:African cassava mosaic virus
184:African cassava mosaic virus
653:, Jumbe A. Ahmed, CABI.
324:Indian cassava mosaic virus
233:Indian cassava mosaic virus
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1002:. Factsheets for Farmers.
427:, flour, and animal feed.
313:which are transmitted by
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58:Scientific classification
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1009:10.1079/pwkb.20157800492
972:"Cassava mosaic disease"
765:10.1079/pwkb.20167801149
432:vegetatively propagated
631:, Plantwise, CABI.
418:Cassava originated in
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1086:Unaccepted virus taxa
994:Ahmed, J. A. (2016).
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317:and primarily infect
35:Cassava mosaic virus
530:tropical rain forest
276:Cassava mosaic virus
647:). Text taken from
625:). Text taken from
549:Manihot melanobasis
542:Control strategies
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402:Hosts and symptoms
339:genomic sequencing
412:Manihot esculenta
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125:Repensiviricetes
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