Common Bean Reaction to Fusarium oxysporum f. sp. phaseoli, the Cause of Severe Vascular Wilt in Central Africa

Abstract

During the September‐December season of 1990, severe symptoms of Fusarium wilt were for the first time observed on a popular climbing bean (Phaseolus vulgaris L.) cultivar. G 2333. introduced within the previous 5 years. Seventy‐three bean genotypes were screened for resistance lo the disease, using artificial inoculation. The effect of inoculation density on the reaction of four selected genotypes was also investigated. Of the 29 climbing bean genotypes evaluated, 19 were resistant, including 11 of the 15 pre‐release or released cultivars. Of the 44 bush bean cultivars evaluated, 28 were resistant, five were intermediate and 11 were susceptible. All susceptible cultivars showed vascular discoloration. In both susceptible and resistant genotypes, the fungus spread almost equally from the entry points in inoculated roots to the base of the plants, but colonization and vertical spread within the vascular system were markedly less in resistant than in susceptible cultivars. At 20 and 30 cm above soil level, the fungus was only recovered from susceptible cultivars. Increasing inoculum density from 102 to 107 conidia/ml did not affect the resistance of cultivars RWR 950 and G 685 but. in the susceptible cultivars G 2333 and MLB‐48‐89 A. it resulted in early appearance, high incidence and severity of the disease.

Reaction to Three Races of Fusarium Wilt in the Phaseolus vulgaris Core Collection

“…phaseoli Kendrick and Snyder (1942), has become an important disease in portions of the central High Plains and western USA. FW is distributed worldwide including Brazil, Colombia, Peru, Costa Rica, Italy, Spain, Greece, the Netherlands, and central Africa (Ribeiro and Hagedorn, 1979a;Armstrong and Armstrong, 1981;Puhalla, 1985;Elias et al, 1993;Diaz-Minguez et al, 1996;Alves-Santos et al, 1999;Buruchara and Camacho, 2000). FW was first identified on common bean in the USA in 1929 (Harter and Weimer, 1929) and in the central High Plains in 1988 (Schwartz et al, 1989).…”

“…FW was first identified on common bean in the USA in 1929 (Harter and Weimer, 1929) and in the central High Plains in 1988 (Schwartz et al, 1989). FW is distributed worldwide including Brazil, Colombia, Peru, Costa Rica, Italy, Spain, Greece, the Netherlands, and central Africa (Ribeiro and Hagedorn, 1979a;Armstrong and Armstrong, 1981;Puhalla, 1985;Elias et al, 1993;Diaz-Minguez et al, 1996;Alves-Santos et al, 1999;Buruchara and Camacho, 2000). Plant stress due to soil compaction, poor soil drainage, and extremes in soil moisture or temperature accentuate disease symptoms and can cause severe yield loss (Schwartz et al, 1996).…”

Quantitative Phenotyping of Vascular Damage Caused by Fusarium Wilt Disease in Cowpea

“…The plant wilt score was highly correlated with both vascular discoloration length (%VDL) and number of necrotic vessels (NFNV) in the seven F 2 populations and one F 2:3 population of cowpea. Associations between wilting and vascular discoloration induced by Fusarium has been reported in tomato, common bean and cotton (Gao et al, 1994; Buruchara and Camacho, 2000; Ulloa et al 2006); however, in soybean, these phenotypic responses were not associated with one another (Luckew et al, 2012). In this study, wilt response was correlated with both %VDL and NFNV, and most of the variability in plant wilt phenotypes was accounted for by both %VDL and NFNV, as indicated by the coefficients of determination ( R 2 all ≥ 0.71); however, the use of only one of the three phenotypes (plant wilt, %VDL or NFNV) alone may not be completely effective in measuring disease severity in the cowpea – Fusarium pathosystem and quite possibly in other plant wilt pathosystems.…”

“…Variation in wilt disease phenotypes has been reported in several studies. In common bean and cotton, extensive and severe colonization of the vascular system occurs on susceptible cultivars and breeding lines, and plant wilting is strongly correlated with vascular discoloration (Pastor Corrales and Abawi, 1987; Buruchara and Camacho, 2000; Ulloa et al, 2006). In both crops, some resistant common bean cultivars and cotton breeding lines exhibited mild wilting and discoloration of vascular tissues.…”

“…Other Fusarium wilt disease severity assessment methods have employed estimates of both plant wilt and vascular discoloration phenotypes by using ordninal rating scales of 0 - 5 (Ulloa et al 2006; Pottorff et al, 2012; Pottorff et al, 2014) or 1 – 9 (adapted from Pastor Corrales and Abawi, 1987) (Fall et al, 2001). However, Pastor Corrales and Abawi (1987) and Buruchara and Camacho (2000) used an ordinal rating scale of 1 – 9 to phenotype plant wilting and a nominal or descriptive scale to estimate extent of vascular discoloration. The severity of vascular damage was described as none, light, intermediate and severe.…”