Breeding for resistance and integrated management of web blight in common bean

Abstract

Common bean (Phaseolus vulgaris L.) production in the humid tropics may increase if less predictable rainfall becomes a serious seed yield constraint in traditional areas of production. The successful production of common bean will require the effective management of common bean diseases favored by hot and humid conditions. Web blight (WB), caused by Thanatephorus cucumeris (Frank) Donk, is a serious disease of common bean in the humid tropics causing significant losses in both seed yield and seed quality. At present, only moderate levels of WB resistance have been identified. Leaf and seed damage and leaf lesion size are criteria that have been successfully used to screen common bean genotypes for WB resistance in the greenhouse and in the field. Pedigree selection has been successfully used to develop cultivars having moderate levels of resistance. Recurrent selection has been used to broaden the genetic base and to produce progeny having higher levels of WB resistance. Sources of resistance from secondary gene pools should be used to combine resistance genes from diverse sources. Common bean cultivars with earlier maturity, deep tap roots, and terminal drought tolerance may be desirable traits for farmers who plant later in the wet season to avoid WB. Seed production during the dry season using irrigation would help to reduce infection of the seed and transmission of the WB pathogen. Minimum tillage techniques are useful to help to reduce the spread of the disease. Biological control may contribute to the management of WB and complement genetic resistance.

Characterization of fungal pathogens and germplasm screening for disease resistance in the main production area of the common bean in Argentina

“…Common bean web blight (WB), caused by the basidiomycete fungus R. solani Kuhn [teleomorph Thanatephorus cucumeris (Frank) Donk] is among the most economically important epidemics, given its level of dispersion in bean production areas in the humid tropics causing significant losses in seed quality and yield ( Beaver et al, 2021 ). Web blight is a limiting factor in Argentina ( Vizgarra et al, 2012 ; Spedaletti et al, 2016 ) and in other regions of Central America and the Caribbean ( Gálvez et al, 1989 ; Godoy-Lutz et al, 2008 ; Mora-Umaña et al, 2013 ), Brazil ( Alves de Sousa et al, 2014 ; Boari et al, 2020 ; Chavarro-Mesa et al, 2020 ), and Africa ( Wortmann et al, 1998 ; Masangano and Miles, 2004 ).…”

“… Beaver et al (2021) recently reviewed the status of breeding for resistance to WB in common bean and although significant progress has been made, common bean cultivars with high levels of resistance to diverse AG groups are still lacking. There are cultivars that in some countries have moderate levels of resistance to WB while in other countries they are more susceptible to the disease ( Poltronieri and Ferreira de Oliveira, 1989 ), emphasizing the fact that local pathogenic WB isolates, characterized by their anastomosis group, should be used in germplasm screening to allow for the identification of sources of genetic resistance ( Beaver et al, 2021 ). Considering this, 23 common bean cultivars inoculated with two highly virulent AG 2-2 isolates collected in northwestern Argentina were evaluated for WB resistance by Spedaletti et al (2017) .…”

Impact of Web Blight on Photosynthetic Performance of an Elite Common Bean Line in the Western Amazon Region of Colombia

“…In addition, some strategies have been implemented for improving genetic resistance of bean lines to manage WB. These include the use of the biological control of fungal pathogens [ 15 ] and the inoculation with Rhizobium strains [ 16 , 17 ], as well as some soil and crop management strategies, such as minimum tillage, crop rotation, wider planting distances between plants, dry season planting, and the use of amendments and organic substrates [ 18 , 19 , 20 , 21 ]. There are also other strategies related to the use of bean lines with indeterminate growth habits because their plant architecture induces less favorable conditions for the development of WB [ 22 ].…”