Epidemiology of sorghum anthracnose (Colletotrichum sublineolum) and leaf blight (Exserohilum turcicum) in Kenya

Abstract

A 3-year study on the epidemiology of sorghum anthracnose (Colletotrichum sublineolum) and leaf blight (Exserohilum turcicum) was conducted at Alupe in western Kenya from 1994 to 1996. A nonlinear logistic model was used to summarize 72 anthracnose and 108 leaf blight disease progress curves from different planting dates and cultivars. Effects of planting date and cultivar on disease development were compared based on estimates of the rate (␤), the absolute rate (), inflection point () and upper asymptote (␥), disease severity at milk stage (v 95), and time taken to reach a disease severity of 2% (t 2 , an estimate of time when disease is first observed). Leaf blight epidemics always started earlier than those of anthracnose, but exhibited lower disease severity at crop maturity. Effects of planting date and cultivar on ␤ varied between years. Delaying planting reduced time to disease onset (i.e. and t 2) and increased absolute rate of progress , resulting in maximum severity at crop 'milk stage' and maturity (v 95 and ␥, respectively). Resistant cultivars had highest and t 2 but lowest , v 95 and ␥ values for both diseases. Delaying planting affected anthracnose progress more on the resistant cultivars, in contrast with leaf blight for which progress on susceptible cultivars was more affected. The implications of these findings for disease management are discussed, and recommendations made to improve disease screening methodologies.

Sorghum [Sorghum bicolor (L.) Moench] breeding for resistance to leaf and stalk anthracnose, Colletotrichum sublineolum, and improved yield: Progress and prospects

“…However, for planting dates to be used as an effective control method in disease management, one has to know the cycle of the disease and find out the optimum time when the diseases reached its optimum/peak levels. Altering of planting dates (Ngugi et al, 2000;Marley 2004), planting disease free seeds, and crop rotation can serve as important methods for controlling sorghum anthracnose disease severity (Warren 1986;Cardwell et al, 1989;Somda et al, 2007). These methods are inexpensive and are environmentally friendly, but may be ineffective especially if they are to be implemented in large fields.…”

Interactions between foliar diseases: concepts and epidemiological approaches

“…Sometimes it is even not clear whether there are any antagonistic or synergistic effects of interacting pathogens, like with Alternaria porri and Stemphylium vesicarium which often occur together in the same purple leaf blotch lesion on Allium species (Suheri & Price, 2000). In some cases the interactions between two diseases may not be detectable due to clear differences in time of disease onset or low disease levels, like for anthracnose (Colletotrichum sublineolum) and leaf blight (Exserohilum turcicum) on sorghum in Kenya (Ngugi et al, 2000).…”

Simple sequence repeat markers associated with anthracnose and <i>Turcicum</i> leaf blight resistance in sorghum

“…Munt.-Cvetk. (anamorph Colletotrichum graminicola) and Turcicum leaf blight (TLB) (Exserohilum turcicum (Pass) Leonard and Suggs (teliomorph: Setosphaeria turcica (Luttrell) Leonard and Suggs) (Ngugi et al, 2000;Ramathani et al, 2011). In many tropical environments, both diseases are endemic with prevalence of different races of E. turcicum and diverse Colletotrichum sublineolum (Ramathani et al, 2011;Sserumaga et al, 2013).…”

“…There is paucity of information on dual resistance in sorghum to both diseases (Ngugi et al, 2000). However, studies conducted separately for each disease show that both qualitative and quantitative resistance mechanisms condition resistance (Paterson, 2008;Tesso et al, 2012;Rajeshwar et al, 2014).…”