White Mold Management in Common Bean by Increasing Within-Row Distance Between Plants

Abstract

White mold of common bean (Phaseolus vulgaris), caused by Sclerotinia sclerotiorum, is a major yield-limiting disease during the fall-winter season in Brazil. This study was conducted to evaluate the efficacy of decreasing within-row densities for an indeterminate growth habit (type IIIa) cultivar, keeping constant the between-row spacing of 0.5 m, to manage the disease. A modification of within-row plant distributions was also attempted in order to reduce white mold intensity. The study was conducted with sprinkler irrigation in two growing seasons (2000 and 2001) in Viçosa, State of Minas Gerais, Brazil, in an area naturally infested with sclerotia. In 2000, treatments were arranged as 3 × 2 × 2 factorial combination of within-row densities (15, 7.5, or 5 plants/m), within-row plant distributions (single and equidistant plants or equidistant groups of three plants), and fluazinam treatments (with or without). In 2001, 16, 12, 8, or 4 plants/m were combined with fluazinam treatments. Fluazinam was applied at both flowering onset and 10 or 13 days later. Average incidence was 92.6% in 2000 and 77.8% in 2001; severity index was 69.8% in 2000 and 40.2% in 2001; and yield was 1,656 kg/ha in 2000 and 2,542 kg/ha in 2001. White mold decreased and yield increased as within-row densities were reduced, regardless of fluazinam treatments. A distribution of equidistant groups of three plants was ineffective in reducing disease. The use of 4 equidistant plants/m in infested irrigated areas was an effective strategy in white mold management.

Sclerotia morphology traits and mycelial growth rate are not informative variables for population studies of Sclerotinia sclerotiorum

“…In Brazil common bean is produced in the springsummer, summer-fall, and fall-winter growing seasons (Vieira et al, 2010). Considering the three growing seasons, MG is the second largest producer, but ranks first during the fall-winter, with an average yield of 2600 kg ha -1 (CONAB, 2013).…”

“…Furthermore, pathogen propagules (sclerotia) can be easily spread over long-distance by contaminated seeds. Sclerotinia sclerotiorum causes white mold in crops such as cotton, soybean, potato, sunflower etc., and is the main soilborne disease affecting common bean (Phaseolus vulgaris L.) in Minas Gerais State (MG), Brazil.In Brazil common bean is produced in the springsummer, summer-fall, and fall-winter growing seasons (Vieira et al, 2010). Considering the three growing seasons, MG is the second largest producer, but ranks first during the fall-winter, with an average yield of 2600 kg ha -1 (CONAB, 2013).…”

Variation in pathogen aggression and cultivar performance against Sclerotinia sclerotiorum in soybean and dry bean from Brazil and the U.S.

“…For example, in a study conducted between 1994 and 2001 in North Dakota, it was shown that for every percent unit increase in white mold incidence, yield was reduced by 12 kg ha -1 in pinto bean and by 23 kg ha -1 in navy bean (Del Río et al 2004). Moreover, without the use of fungicide control, dry bean yield loss to white mold in Brazil has been reported to vary from 17 to 54% (Miorini et al 2017;Vieira et al 2010). …”

“…For both crops, it is recommend to integrate cultural and chemical control measures. Increasing plant spacing is an important factor and has been shown previously to reduce disease (Paula Junior et al 2009, Vieira et al 2010) because increased air flow within the plant canopy reduces microclimatic effects that favor secondary spread of the pathogen. For example, increased row spacing from 19 to 75 cm showed disease severity was reduced from 25 to 41% (Peachey et al 2006).…”

Estimativa de severidade do mofo-branco em lavouras de feijão utilizando-se sensores hiper e multiespectral

“…As plantas dentro da área útil de cada parcela foram avaliadas individualmente usando uma escala de notas de 0 a 4, em que 0 = planta sadia; 1 = 1 a 25% da planta com sintoma de mofo-branco; 2 = 26 a 50% da planta com sintoma; 3 = 51 a 75% da planta com sintoma e 4 = acima de 76% da planta com sintoma. O índice de severidade de doença (ISD) no estádio fenológico R9 (maturação das plantas), em cada parcela, foi calculado com base na equação de Vieira et al (2010):…”