Titles (40)Keywords (1)Abstracts (5)
Assessing severity of postural loading in four gari-frying methods, Samuel, T. M.*, Igbeka, J. C.* and Kolawole, P., in: ASSET, volume 8, number 2, pages 191-198, ISSN 1595-9694, 2009.
 
Assessing the severity and the incidence of Cassava Root Necrosis Disease (CRND) in western Democratic Republic of Congo, Bakelana, T.*, Pita, J., Mwangu, K.*, Tevo, N.*, Mayanza, K.*, Betezi, M.*, Tuwizana, N.*, Mukendi, T.*, Tshiamala, N.*, Mahungu, N., Monde, G.*, Munseki, L.*, Kanana, T.* and Kalonji, M.*, in: International Journal of Agriculture, Environment and Bioresearch, volume 4, number 6, pages 237-253, ISSN 2456-8643, 2019. [DOI]
 
Assessment of the cropping cycle effects on black leaf streak severity and yield decline of plantain and plantain hybrids, Mobambo, K., Gauhl, F., Swennen, R. and Pasberg-Gauhl, C., in: International Journal of Pest Management, volume 42, number 1, pages 1-7, 1996.
 
Disease incidence and severity in cowpea lines evaluated for resistance to single and multiple infections of endemic viruses in Nigeria, Ogunsola, K. E., Ilori, C. O.*, Fatokun, C., Boukar, O., Ogunsanya, P. and Kumar, P. L., in: Journal of Crop Improvement, pages 1-26, ISSN 1542-7528, 2020. [DOI]
 
Distribution and severity of Yam anthracnose in Nigeria, Akem, C. and Asiedu, R., in: Root Crops for food security in Africa: proceedings of the Fifth Triennial Symposium of the International Society for Tropical Root Crops-Africa Branch, 22-28 November 1992, Kampala, Uganda, pages 297-301, ISTRC-AB; CTA; International Institute of Tropical Agriculture (IITA), 1994.
 
Distribution, incidence and severity of Cassava diseases and pests in Mozambique, Toko, M., Hanna, R., Legg, J., Andrade, M., Jone, A., Agboton, B., Otema, M, Okao-Okuja, G., Obonyo, R. and Mambo, E., in: Proceedings of the 9th ISTRC-AB Symposium, pages 623-633, Mombasa, Kenya, 2007.
 
Distribution, incidence and severity of viral diseases of yam (Dioscorea spp.) in Cote d'Ivoire, Toualy, M. N. Y., Diallo, H.*, Akinbade, S., Seka, K.* and Kumar, P. L., in: African Journal of Biotechnology, volume 13, number 3, pages 465-470, ISSN 1684-5315, 2014. [DOI]
 
Distribution, prevalence, and severity of damages caused by nematodes on yam (Dioscorea Rotundata) in Nigeria, Kolombia, Y. A., Kumar, P. L., Adewuyi, O., Korie, S., Viaene, N., Bert, W. and Coyne, D., in: Nematropica, volume 50, number 1, pages 1-18, ISSN 0099-5444, 2020.
 
Effect of detopping on disease incidence and symptom severity of African cassava mosaic virus disease (ACMD) on some newly developed cassava cultivars form landraces introgression, Ariyo, O., Atiri, G.* and Dixon, A., in: Acta Phytopathologica et Entomologica Hungarica, volume 38, pages 115-124, ISSN 0238-1249, 2003.
 
Effect of intra row spacing on the incidence and severity of pearl millet downy mildew and grain yield, Zarafi, A. and Emechebe, A., in: Archives of Phytopathology and Plant Protection, volume 39, number 1, pages 9-14, 2006.
 
Effect of planting date on severity of frogeye leaf spot and grain yield of soybeans, Akem, C. and Dashiell, K., in: Crop Protection, volume 13, number 8, pages 607-610, ISSN 0261-2194, 1994.
 
Effect of soils, cropping system and host phenotype on incidence and severity of Striga gesnerioides on cowpea in West Africa, Cardwell, K. and Lane, J. A., in: Agriculture, Ecosystems and Environment, volume 53, number 3, pages 253-262, ISSN 0167-8809, 1995.
 
Effect of staking and non-staking systems on disease severity, yield and quality attributes of yams (Dioscorea alata), Norman, P. E.*, Whyte, J., Samura, A. E.*, Massaquoi, A.*, Sessay, L.*, Dixon, A., Fomba, S. N.*, Benya, M.T.* and Sowa, M.*, in: Journal of Agriculture and Ecology Research International, volume 2, number 4, pages 219-229, ISSN 2394-1073, 2015. [DOI]
 
Effects of soil pasteurization and soil N status on severity of Striga hermonthica (Del.) Benth. in maize, Ahonsi, M., Berner, D. K., Emechebe, A. and Lagoke, S.*, in: Soil Biology and Biochemistry, volume 34, number 11, pages 1675-1681, ISSN 0038-0717, 2002.
 
Effects of time of maize streak virus infection on disease severity and yield in maize inbred lines, Salaudeen, M., Menkir, A., Atiri, G.* and Kumar, P. L., Abstract in Book of abstracts of the 36th annual conference of the Nigerian Society of Plant Protection (NSPP), 4 - 8 September, Futa, Nigeria., 2011.
 
Enhanced symptom severity and pseudorecombination of geminiviruses are important factors in possible breakdown of resistance to cassava mosaic disease, Ariyo, O., Koerbler, M., Dixon, A. and Atiri, G.*, in: Book of Abstracts of the 9th Triennial Symposium of the International Society for Tropical Root Crops-Africa Branch, 31 October-5 November 2004, Mombasa, Kenya, 2004.
 
Enhanced symptom severity and pseudorecombination of geminiviruses are important factors in possible breakdown of resistance to cassava mosaic disease, Ariyo, O., Dixon, A., Atiri, G.*, Koerbler, M. and Winter, S., in: Proceedings of 9th ISTRC-AB symposium, pages 711-718, Mombasa, Kenya, 2007.
 
Exploring quantitative trait nucleotides associated with response to yam mosaic virus severity and tuber yield traits in Dioscorea praehensilis Benth. germplasm via genome-wide association scanning, Adewumi, A. S., Adejumobi, I. I., Opoku, V. A.*, Asare, P. A.*, Adu, M. O.*, Taah, K. J.*, Stanley, A. E.*, Olatunde, T. E.*, Afutu, E.*, Akaba, S.*, Mushoriwa, H . and Agre, A. P., in: Frontiers in Horticulture, volume 3, number - :1459476, pages 1-15, ISSN 2813-3595, 2024. [DOI]
 
Field evaluation of root rot disease and relationship between disease severity and yield in cassava, Onyeka, T., Dixon, A. and Ekpo, E.*, in: Experimental Agriculture, volume 41, number 3, pages 357-363, 2005.
 
Genotype x environment effects on severity of cassava bacterial blight disease caused by Xanthomonas axonopodis pv. manihotis, Dixon, A., Ngeve, J. and Nukenine, E., in: European Journal of Plant Pathology, volume 108, number 8, pages 763-770, 2002.
 
Impact of timing and method of virus inoculation on the severity of wheat streak mosaic disease, Wosula, E. N., McMechan, A. J., Knoell, E., Tatineni, S., Wegulo, S. N. and Hein, G. L., in: Plant Disease, volume 102, number 3, pages 645-650, ISSN 0191-2917, 2018. [DOI]
 
Incidence and severity of cassava mosaic disease in the Republic of Congo, Ntawuruhunga, P., Okao-Okuja, G., Bembe, A., Obambi, M., Armand Mvila, J. and Legg, J., in: African Crop Science Journal, volume 15, number 1, pages 1-9, 2007.
 
Incidence and severity of postharvest tuber rot disease among four Dioscorea species, Dania, V., Fadina, O.*, Ayodele, M. and Kumar, P. L., Abstract, p. 11 in the Nigerian Society of Plant Pathology(NSPP), 37th annual conference book of programme and abstracts. 6 - 10 May 2012, Federal University of Agriculture, Abeokuta, Ogun state, Nigeria, 2012.
 
Incidence and severity of yam internal brown spot disease in Cote d'Ivoire, Toualy, M.N.Y.*, Diallo, H.* and Kumar, P. L., Abstract, P.324 in the Book of Abstracts, 16th Triennial Symposium of the International Society for Tropical Root Crops (ISTRC), 23 - 28th September, 2012.
 
Methods of surveying the incidence and severity of cassava mosaic disease and whitefly vector populations on cassava in Africa: a review, Sseruwagi, P., Sserubombwe, W.*, Legg, J., Ndunguru, J.* and Thresh, J. M., in: Virus Research, volume 100, number 1, pages 129-142, ISSN 0168-1702, 2004.
 
Optimum sample size for determining disease severity and defoliation associated with Septoria leaf spot of blueberry, Ojiambo, P. and Scherm, H., in: Plant Disease, number 9, pages 1209-1213, 2006.
 
Prevalence and severity of bacterial blight and anthracnose diseases of cassava in different agro-ecological zones of Nigeria, Onyeka, T., Owolade, F., Ogunjobi, A.*, Dixon, A., Okechukwu, R., Bandyopadhyay, R. and Bamkefa, B., in: African Journal of Agricultural Research, volume 3, number 4, pages 297-304, ISSN 1991-637X, 2008.
 
Prevalence and severity of Nattrassia mangiferae root and stem pathogen of cassava in Benin, Msikita, W., Bissang, B., James, B., Baimey, H., Wilkinson, H., Ahounou, M. and Fagbemissi, R.*, in: Plant Disease, volume 89, number 1, pages 12-16, ISSN 0191-2917, 2005.
 
Quantitative methods for assessing the severity of anthracnose on yam (Dioscorea alata), Simons, S. A. and Green, K., in: Tropical Science, volume 34, pages 216-224, ISSN 0041-3291, 1994.
 
Relative severity of aflatoxin contamination of cereal crops in West Africa, Bandyopadhyay, R., Kumar, M. and Leslie, J., in: Food Additives and Contaminants, volume 24, number 10, pages 1109-1114, ISSN 0265-203X, 2007. [DOI]
 
Relative severity of fumonisin contamination of cereal crops in West Africa, Vismer, H.*, Shephard, G. S.*, Rheeder, J. P.*, van der Westhuizen, L.* and Bandyopadhyay, R., in: Food Additives and Contaminants: Part A, pages 1-7, ISSN 1944-0049, 2015. [DOI]
 
Severity of anthracnose and virus diseases of water yam (dioscorea alata L.) in NIgeria I: effects of yam genotype and date of planting, Egesi, C. N.*, Onyeka, T. and Asiedu, R., in: Crop Protection, volume 26, number 8, pages 1259-1265, ISSN 0261-2194, 2007.
 
Severity of citrus tristeza virus isolates from Texas, Herron, C., Mirkov, T., Solis-Gracia, N., Kahlke, C., Skaria, M. and Da Graca, J., in: Plant Disease, volume 89, number 6, pages 575-580, ISSN 0191-2917, 2005.
 
Severity of Curvularia stem blight disease of cassava in West Africa, Msikita, W., Baimey, H. and James, B., in: Plant Disease, volume 91, number 11, pages 1430-1435, ISSN 0191-2917, 2007.
 
Survey on incidence and severity of Stenocarpella macrospora (Earle) leaf blight of maize in the mid-altitude zone of Nigeria, Olatinwo, R. O., Deadman, M., Cardwell, K. and Julian, A. M., in: International Journal of Pest Management, volume 45, number 4, pages 259-262, ISSN 0967-0874, 1999.
 
Symptom severity of cassava mosaic disease in relation to concentration of African cassava mosaic virus in different cassava genotypes, Ogbe, F., Atiri, G.*, Thottappilly, G. and Dixon, A., in: Plant Pathology, volume 52, pages 84-91, 2003.
 
Symtom severity of cassava mosaic disease in relation to concentration of African cassava mosaic virus in different cassava genotypes, Ogbe, F., Atiri, G.*, Dixon, A. and Thottappilly, G., in: Plant Pathology, volume 52, pages 84-91, ISSN 0032-0862, 2003.
 
The effect of cassava mosaic geminiviruses on symptom severity and growth of a susceptible cassava cultivar in Uganda, Owor, B., Legg, J., Kyamanywa, S.*, Osiru, D.* and Ogenga-Latigo, M.*, in: Paper presented at: Fourth regional meeting of the Forum on Agricultural Resource Husbandry, Lilongwe, Malawi, 10-14 July, 2000.
 
The effect of cassava mosaic geminiviruses on symptom severity, growth and root yield of a cassava mosaic virus disease-susceptible cultivar in Uganda, Owor, B., Legg, J., Okao-Okuja, G., Obonyo, R. and Ogenga-Latigo, M.*, in: Annals of Applied Biology, volume 145, number 3, pages 331-337, ISSN 0003-4746, 2004.
 
The influence of farm resources and management decisions on the severity of striga infestation and maize productivity in western Kenya, Rusinamhodzi, L ., Nguyen, E., Marrou, H., Uzamushaka, S. and Corbeels, M., in: Weed Research, pages 1-14, ISSN 0043-1737, 2024. [DOI]
 
Prevalence and severity of bacterial blight and anthracnose diseases of cassava in different agro-ecological zones of Nigeria, Onyeka, T., Owolade, F., Ogunjobi, A.*, Dixon, A., Okechukwu, R., Bandyopadhyay, R. and Bamkefa, B., in: African Journal of Agricultural Research, volume 3, number 4, pages 297-304, ISSN 1991-637X, 2008.
 
Keywords:anthracnose, bacterial blight, cassava, Colletotrichum gloeosporioides prevalence, severity, Xanthomonas axonopodis

Evaluation of water yam (Dioscorea alata L.) germplasm for reaction to yam anthracnose and virus diseases and their effect on yield, Egesi, C. N.*, Odu, B., Ogunyemi, S., Asiedu, R. and Hughes, J., in: Journal of Phytopathology, volume 155, number 9, pages 536-543, 2007.
 
Abstract:
Use of genetic resistance is the most practical and economic way to manage major diseases of yams. In a search for sources of resistance, 40 water yam (Dioscorea alata L.) accessions from Benin, Ghana, Nigeria and Puerto Rico were screened under natural disease infection conditions in Ibadan, Nigeria. The accessions were evaluated at 1, 3 and 6 months after planting (MAP) for severity of yam anthracnose and viral diseases. The effect of the pathogens on yield was also evaluated at harvest 9 MAP. There were significant differences (P < 0.001) between accessions for severities of anthracnose and viral diseases. Eight (20%) of them had lower anthracnose area under disease progress curves (AUDPC) values than the resistant check while 10 (25%) had AUDPC values below the trial mean. There were significant variations (P < 0.001) in yield components among the accessions. There was significant negative correlation of anthracnose severity with fresh tuber yield (r = -0.51) and with number of tubers per plot (r = -0.40). Similarly, significant negative correlations were observed of virus disease severity with fresh tuber yield (r = -0.78) and number of tubers per plot (r = -0.65). Linear regression models also showed that the fresh yield had significant negative relationships with anthracnose (R2 = 0.26) and viral (R2 = 0.62) diseases. The accessions identified as resistant constitute a valuable resource for breeding of resistant germplasm.

Novel sources of resistance to Fusarium stalk rot of maize in tropical Africa, Afolabi, C., Ojiambo, P., Ekpo, E.*, Menkir, A. and Bandyopadhyay, R., in: Plant Disease, volume 92, number 5, pages 772-780, ISSN 0191-2917, 2008.
 
Abstract:
Fusarium stalk rot is one of the most widespread and destructive diseases of maize, and deployment of resistant genotypes is one of the most effective strategies for controlling the disease. Fifty inbred lines and four checks from the breeding program of the International Institute of Tropical Agriculture were evaluated in field trials at Ikenne and Ibadan, Nigeria in 2003 and 2004 to identify new sources of resistance to stalk rot caused by Fusarium verticillioides. Evaluations were conducted under artificial inoculation and natural infection at Ibadan and Ikenne, respectively. Disease severity was recorded using a severity scale (SS) and direct estimation of stalk discoloration (SD). The two methods of disease assessment were compared and combined to classify genotypes into resistance groups using results from rank-sum analysis. In 2003, disease severity ranged from SS = 1 to 5 and SD = 1.3 to 33.8% at both locations. Both SS and SD were significantly (P < 0.01) higher in 2003 than in 2004 at the two locations. In both years, inbred lines significantly differed in SS (P < 0.02) and SD (P < 0.04) at Ibadan. Similarly, inbred lines significantly differed in SS (P < 0.04) and SD (P < 0.04) when genotypes were evaluated at Ikenne. Disease assessments based on SS and SD were significantly correlated (0.68 < r < 0.95, P < 0.01) in both years. Based on the results from rank-sum analysis, inbred lines were separated into highly resistant, resistant, moderately resistant, moderately susceptible, susceptible, and highly susceptible groups. At Ibadan, 6 (11.1%) and 8 (14.8%) were identified as highly resistant and resistant, respectively, whereas 11 (20.4%) were identified as resistant at Ikenne. Inbred lines 02C14609, 02C14643, 02C14654, and 02C14678 were consistently classified as either highly resistant or resistant to stalk rot across locations and years while the check genotypes were classified either as susceptible or moderately susceptible to stalk rot. These four inbred lines identified to have high levels of disease resistance may be used for breeding maize with resistance to Fusarium stalk rot.

Perception of farmers in Benin, West Africa to Imperata cylindrica, Ayeni, S., Avocanh, A. and Beed, F., in: Proceedings of the 4th International Weed Science Congress, 20-24th June, Durban, South Africa, pages 45, 2004.
 
Abstract:
Questionnaires and sampling techniques were developed to assess the distribution, problems caused by, and the efficacy of control methods for Imperata cylindrica (L.) Raeuschel. One hundred farmers were interviewed from each of the three agro-ecological zones of Benin. These differ in climate, especially annual rainfall, and in crops cultivated. I. cylindrica was the most serious weed in the high and medium rainfall zones but was less prevalent in the arid zone. In all zones, the recent intensification of agricultural land use caused a reduction in the use of fallow and cover crops, resulting in increased incidence and severity of I. cylindrica. Significant yield losses due to I. cylindrica infestation were reported for all crops, including cassava, cotton, cowpea, maize, millet, peanut, sorghum, and yam. Furthermore, the clearance of vegetation by “slash and burn” agriculture encouraged rapid leaf growth from rhizomes to create dense stands of I. cylindrica that virtually eliminated other species. Such areas were frequently abandoned because existing control methods were ineffective. Weeding by hand caused cuts due to sharp leaf margins and leaf tips occasionally caused injury leading to blindness. Frequent ploughing can break rhizome sections into pieces sufficiently small to avoid plant regeneration, but was considered too time and labour intensive. Of the 300 farmers surveyed, none used chemical herbicides, due to high cost. This study showed the need to develop sustainable methods of I. cylindrica control for resource poor farmers.

Screening landraces for additional sources of field resistance to Cassava Mosaic Disease and green mite for integration into the Cassava Improvement Program, Raji, A., Ladeinde, O.* and Dixon, A., in: Journal of Integrative Plant Biology, volume 50, number 3, pages 311-318, 2008.
 
Abstract:
Twelve cassava landraces were evaluated for sources of resistance genes to diseases and pests of major economic importance in Africa. The objective was to assess their levels of field resistance to mosaic disease (ACMD), bacterial blight (CBB), anthracnose (CAD), and green mite (CGM), compared to TMS30572, an elite cultivar widely adopted in Africa. Considerable genotypic variation was observed among cultivars for resistance to ACMD and CGM but not for CBB and CAD. The lowest mean incidence of 12% and severity of 1.8 on a scale of 1-5 for ACMD was recorded for Atu, a landrace with farmer acceptable qualities. In comparison, the improved cultivar, TMS 30572, had a mean disease incidence of 72% and a severity score of 2.8. Another landrace, MS-20 had the lowest CGM damage score (2.1) while TMS 30572 emerged as one of the susceptible cultivars with a damage score of 3. Additional sources of resistance to ACMD and CGM that may possibly be better than the popular improved cultivar, TMS 30572, were identified in this study. These could serve as novel sources of additional genes to complement existing resources for elite cassava breeding in Africa.

Severity of anthracnose and virus diseases of water yam (dioscorea alata L.) in NIgeria I: effects of yam genotype and date of planting, Egesi, C. N.*, Onyeka, T. and Asiedu, R., in: Crop Protection, volume 26, number 8, pages 1259-1265, ISSN 0261-2194, 2007.
 
Abstract:
Anthracnose and virus diseases exert devastating impacts on yam production in many tropical regions of the world where the crop contributes to food security and income generation. The complexities in their epidemiology necessitate the use of integrated approaches in their management. Six genotypes of Dioscorea alata, planted on six dates (March?August) in each of 1998 and 1999 in Ibadan, Nigeria, were evaluated to determine the effects of planting date and genotype on severity of the two diseases. The date of planting had a profound influence on anthracnose severity, contributing 72% of the observed variation due to combined effects of planting date, genotype and their interactions. In contrast, the genotype effect was most dominant with respect to virus severity, accounting for 85% of the total observed variation. Planting in August supported least anthracnose development while April and May plantings resulted in the least severity of virus diseases. While selection of planting time could be used to manage anthracnose disease, its application could be influenced by the prevailing weather conditions in a particular location. Two of the genotypes (TDa 291 and TDa 297) had low severity values for both diseases across the different planting dates. Availability of such sources of multiple disease resistance and appropriate choice of planting date would be very useful in integrated management of the two major yam diseases.