Incidence, Severity and Gravity of Cassava Mosaic Disease in Savannah Agro-Ecological Region of DR-Congo: Analysis of Agro-Environmental Factors

Marcel Muengula-Manyi, Kabwe K. Nkongolo, Claude Bragard, Patrick Tshilenge-Djim, Stephan Winter, Adrien Kalonji-Mbuyi

Department of Biology, Laurentian University, Sudbury, Ontario, Canada.
Earth and Life Institute, Applied Microbiology-Phytopathology, Univer-sité Catholique de Louvain, Louvain-la-Neuve, Belgium.
Plant Virus Collection, DSMZ Deutsche Sammlung von Mikroorganismen und Zellkuturen GmbH, Braunschweig, Germany.
Unit of Phytopathology, Faculty of Agronomy, University of Kinshasa, Kinshasa, Democratic Republic of Congo.

DOI: 10.4236/ajps.2012.34061                

Abstract

African Cassava mosaic disease (ACMD) is the most severe and widespread disease caused by viruses limiting production of the crop in sub-Saharan Africa. The objective of the present study was to evaluate CMD incidence, severity, and gravity under different agro-environmental conditions. A total of 222 fields were surveyed in 23 different locations. All the farmers grow only local cassava varieties without applications of fertilizers. Overall, mean CMD incidences for all sites surveyed were 58.2% and 51.7%, in 2009 and 2010, respectively. Disease severity ranged from 2.4 to 3.1 on a scale of 1 to 5. Mean disease gravity varied from 29.7% to 62%, in 2010, and 2009, respectively. Detailed analysis of agronomic and environmental revealed no significant association between cassava stand locations, age, land topography and the development of CMD. Likewise intercropping practices and field topping did not affect the development of CMD in all the fields surveyed. There were significant differences in the number of white flies (Bemisia tabaci) per plant in 2009 and 2010, but no significant correlations between the number of B. tabaci per plant and CMD incidence, severity, and gravity was found. In most fields, CMD appears to originate mostly from unhealthy cassava cuttings used for planting.

Keywords

Cassava Mosaic Disease; Farmers’ Fields; Agro-Environmental Factors; Gandajika; DR-Congo

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	G. H. De Bruinjn and C. O. Fresco, “The Importance of Cassava in World Food Production,” Netherland Journal of Agricultural Sciences, Vol. 37, No. 5, 1989, pp. 21-34.
[2]	A. A. C. Alves, “Cassava Botany and Physiology,” In: R. J. Hillocks, J. M. Thresh and A. C. Bellotti, Eds., Cassava: Biology, Production and Utilization, CAB International, Wallingford, 2002, pp. 67-89. doi:10.1079/9780851995243.0067
[3]	J. C. Lozano, “Overview of Integrated Control of Cassava Diseases,” Fitopatologia Brasileira, Vol. 17, 1992, pp. 18-22.
[4]	J. M. Thresh, G. W. Otim-Nape, J. P. Legg and D. Fargette, “African Cassava Mosaic Virus Disease: The Magnitude of the Problem,” African Journal of Root and Tu-ber Crops, Vol. 2, No. 1, 1997, pp. 13-19.
[5]	P. Ntawuruhunga, G. Okao-Okuja, A. Bembe, M. Obambi, J. C. A. Mvila and J. P. Legg, “Incidence and Severity of Cassava Mosaic Disease in the Republic of Congo,” African Crop Science Journal, Vol. 15, No. 1, 2007, pp. 1-9.
[6]	B. R. Harrison, H. Barker, K. R. Bock, J. Guthrie, G. Meredith and M. Atkinson, “Plant Viruses with Circular Single Stranded DNA,” Nature London, Vol. 270, 1977, pp. 760-762. doi:10.1038/270760a0
[7]	S. K. Hahn, “Breeding Cassava for Resistance to Cassava Mosaic Disease,” Euphytica, Vol. 29, No. 2, 1980, pp. 673-683. doi:10.1007/BF00025127
[8]	D. Fargette, J. C. Thouvenel and C. Fauquet, “Virus Content of Leaves of Cassava Infected by African Cassava Mosaic Virus,” Annals of Applied Biology, Vol. 110, No. 1, 1986, pp. 65-73. doi:10.1111/j.1744-7348.1987.tb03233.x
[9]	J. Dubern, “Transmission of African Cassava Mosaic Geminivirus by the Whitefly (Bemisia tabaci),” Tropical Science, Vol. 34, 1994, pp. 82-91.
[10]	R. J. Hillocks and J. M. Thresh, “Cassava Mosaic and Cassava Brown Streak Virus Diseases in Africa: A Comparative Guide to Symptoms and Etiologies,” Roots, Vol. 7, No. 1, 2000, pp. 1-8.
[11]	L. A. Calvert and J. M. Thresh, “The Viruses and Virus Diseases of Cassava,” In: R. J. Hillocks, J. M. Thresh and A. C. Bellotti, Eds., Cassava: Biology, Production and Utilization, CAB International, Wallingford, 2002, pp. 237-260. doi:10.1079/9780851995243.0237
[12]	J. C. Zadock, “On the Conceptual Basis of Crop Loss Assessment: The Threshold Theory,” Annual Review of Phytopathology, Vol. 23, No. 1, 1985, pp. 455-473. doi:10.1146/annurev.py.23.090185.002323
[13]	A. C. Bellotti, L. Smith and S. L. Lapointe, “Recent Advances in Cassava Pest Management,” Annual Review of Entomology, Vol. 44, 1999, pp. 343-370. doi:10.1146/annurev.ento.44.1.343
[14]	P. Sseruwagi, G. W. Otim-Nape, D. S .O. Osiru and J. M. Thresh, “Influence of NPK Fertiliser on Populations of the Whitefly Vector and Incidence of Cassava Mosaic Virus Disease,” African Crop Sciences Journal, Vol. 11, No. 3, 2003, pp. 171-179.
[15]	M. Muengula-Manyi, K. K. Nkongolo, C. Bragard, P. Tshilenge-Djim, S. Winter and A. Kalonji-Mbuyi, “Effect of NPK Fertilization on Cassava Mosaic Disease Expression in a Sub-Saharan African Region,” International Journal of Agricultural Research, 2011, Article in Press.
[16]	J. P. Legg and J. M. Thresh, “Cassava Mosaic Virus Disease in East Africa: a Dynamic Disease in a Changing Environment,” Virus Research, Vol. 71, No. 1-2, 2000, pp. 135-149. doi:10.1016/S0168-1702(00)00194-5
[17]	J. P. Legg, B. Owor, P. Sseruwagi and J. Ndunguru, “Cassava Mosaic Virus Disease in East and Central Africa: Epidemiology and Management of Regional Pandemic,” Advances in Virus Research, Vol. 67, 2006, pp. 355-418. doi:10.1016/S0065-3527(06)67010-3
[18]	O. A. Ariyo, A. G. O. Dixon and G. I. Atiri, “Whitefly Bemisia tabaci (Homoptera: Aleyrodidae) Infestation on Cassava Genotypes Grown at Different Ecozones in Nigeria,” Journal of Economic Entomolgy, Vol. 98, No. 2, 2005, pp. 611-617. doi:10.1603/0022-0493-98.2.611
[19]	W. S. Sserubombwe, J. M. Thresh, G. W. Otim-Nape and D. S. O. Osiru, “Progress of Cassava Mosaic Virus Disease and Whitefly Vector Populations in Single and Mixed Stands of Four Cassava Varieties Grown under Epidemic Conditions in Uganda,” Annals of Applied Biology, Vol. 138, No. 2, 2001, pp. 161-170. doi:10.1111/j.1744-7348.2001.tb00098.x