Occurrence and estimated losses caused by cassava viruses in Migori County, Kenya

Abstract

A farm survey was conducted in Kuria East and Suna West sub-counties to determine the incidence, severity and estimated losses of cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) on cassava crops in farmers' fields. The results showed that cassava is the second most important staple crop after maize in Migori County. CMD incidence ranged from 0.0 to 56.7%) in Kuria East and 10.0 to 55.0% in Suna West. CBSD incidences were much higher at 5.0 to 74.0% in Kuria East and 10.0 to 77.5% in Suna West. Both CMD and CBSD had an effect on yield reduction and total root loss ranged from 10.7 to 47.2% in Kuria East and 11.5 to 33.2 in Suna West. The percent mean total root loss in Kuria East was 25.9%; equivalent to 1299.6 US dollars/ha while in Suna East was 24.7%; equivalent to 1259.5 US dollars/ha. The best performing variety with regards to low CBSD and CMD incidence, low root losses and high yield were TMS 30572 and MH95/0183. The findings of this study are expected to provide impetus for the development and promotion of new high yielding, locally adapted and resistant cassava varieties.

The Search for Resistance to Cassava Mosaic Geminiviruses: How Much We Have Accomplished, and What Lies Ahead

“…For example, in Uganda, where the latest CMD pandemic first emerged in the 1990s, the IITA varieties were resistant to CMD, and to a lesser extent, cassava brown streak disease (CBSD), caused by cassava brown streak viruses (CBSVs) in East Africa (Ntawuruhunga et al, 2013; Pariyo et al, 2015; Patil et al, 2015). Similar successes have been recorded in other eastern and southern African countries (Ntawuruhunga et al, 2013; Mbewe et al, 2015; Masinde et al, 2016). In Zambia, eight IITA varieties outperformed local varieties significantly, resulting in increased yields, household income, and food security (Khonje et al, 2015).…”

“…Tuberous root losses due to CMD may reach 100% in highly susceptible varieties (Thresh et al, 1994; Masinde et al, 2016) or in mixed infections (Fondong et al, 2000a; Pita et al, 2001). Generally, there are three objectives to decreasing losses caused by virus diseases: (1) decrease the proportion of plants that become infected; (2) delay infection to such a late stage of crop growth that losses become unimportant; (3) decrease the severity of damage sustained after infection has occurred (Thresh and Cooter, 2005).…”

Incidence, severity and distribution of Cassava brown streak disease in northeastern Democratic Republic of Congo

“…CBSD is caused by two distinct viruses: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) that generally cause similar root necrosis in infected plants (Bakelana et al, 2018;Legg et al, 2011;Masinde et al, 2016;Mbanzibwa et al, 2009;Ndunguru et al, 2015;Vanderschuren et al, 2012;Winter et al, 2010). CBSD-causing viruses are semi-persistently transmitted by the whitefly Bemisia tabaci (Gennadius) (Njoroge et al, 2017), however, aphids are been identified as potential vectors of CBSV (Ateka et al, 2017;Mulenga et al, 2018).…”

New opportunities and challenges to engineer disease resistance in cassava, a staple food of African small-holder farmers

“…A recent report from Kenya estimates US$1,300/hectare losses [5]. Both viruses are transmitted by the whitefly vector Bemisia tabaci .…”

“…The two viral diseases, CMD and CBSD, have a major impact on cassava production in sub-Saharan Africa, together causing estimated losses of US$1 billion per year [ 4 ]. A recent report from Kenya estimates US$1,300/hectare losses [ 5 ]. Both viruses are transmitted by the whitefly vector Bemisia tabaci .…”