Reação de genótipos de algodoeiro à mancha de Ramularia em diferentes épocas e ambientes

Cia, Edivaldo; Fuzatto, Milton Geraldo; Kondo, Julio Isao; Ohl, Guilherme de Almeida; Galbieri, Rafael

doi:10.1590/s0100-54052013000300008

Cited by 10 publications

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“…Cia et al (2013) found that this cultivar presented resistance to RLS in the Primavera do Leste MT and susceptibility in Ituverava SP, which indicates a genetic variation of the pathogen. Silva et al (2011) found results similar to those from the ST2, with the cultivars FMT705, FMT709 and IMACD8276 with similar resistance levels.…”

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confidence: 69%

Severity of Ramularia Leaf Spot and Seed Cotton Yield in Different Sowing Times

et al. 2016

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-The ramularia leaf spot (RLS) disease causes cotton yield losses. Choosing a less susceptible cultivar and a sowing time that are less favorable to the pathogen contribute to the management of this disease. The objective of this work was to evaluate the severity of ramularia leaf spot on cotton cultivars sowed in two different times. The experiment was conducted in a triple factorial design (4x3x2), consisted of four cultivars, the three thirds of the plant and two sowing times, with four replications. Each plot was divided in two twin plots, one with fungicide application (with disease control) and the other without fungicide application (without disease control). The severity assessments were performed every seven days, considering each third of the plant with a diagrammatic scale. Yield was evaluated in each plot. There was a significant interaction between sowing times and the thirds of the plant in the plots without disease control for RLS severity, with the highest values of area under the disease progress curve (AUDPC) in the first sowing time (ST1) and in the lower third of the plant. The FMT705 cultivar had the highest and FM951LL the lowest value of AUDPC. The AUDPC of these cultivars were no statistically different in the second sowing time (ST2), but they had higher AUDPC values in the lower third. Highest yields were found with ST1 in plots with disease control, with no differences between the cultivars, however, lower yields were found in plots without disease control.Keywords: Gossypium hirsutum L. Ramularia areola. Thirds of the plant. RELAÇÃO ENTRE SEVERIDADE DA MANCHA DE RAMULÁRIA E PRODUTIVIDADE DE ALGODOEIRO EM DUAS ÉPOCAS DE SEMEADURARESUMO -A mancha de ramulária promove perdas de produtividade do algodoeiro, em que a escolha da cultivar menos suscetível e a época de semeadura menos favorável ao patógeno contribuem para o manejo da doença. O objetivo deste estudo foi avaliar a severidade da mancha de ramulária em cultivares de algodão conduzido em duas épocas de semeadura. O experimento foi conduzido em esquema fatorial triplo (4x3x2), sendo quatro cultivares, três terços da planta e duas épocas de semeadura, com quatro repetições. Cada parcela foi dividida em duas parcelas gêmeas, onde uma parcela recebeu aplicação de fungicidas (com controle) e a outra parcela não recebeu aplicação de fungicidas (sem controle). As avaliações de severidade foram feitas a cada sete dias, considerando cada terço da planta com auxílio de uma escala diagramática. A produtividade foi avaliada na área útil de cada parcela gêmea. Houve interação significativa entre as épocas de semeadura e terços da planta nas parcelas sem controle, onde os maiores valores da área abaixo da curva de progresso da severidade (AACPS) da mancha de ramulária foram observados na primeira época de semeadura (ES1) e no terço inferior da planta. As cultivares FMT 705 e FM 951 LL apresentaram menor e maior valor de AACPS, respectivamente. Na segunda época de semeadura (ES2), as cultivares não diferiram estatisticamente para AACPS,...

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confidence: 69%

Severity of Ramularia Leaf Spot and Seed Cotton Yield in Different Sowing Times

et al. 2016

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“…An interaction between genotypes and Ramularia isolates was also observed in this study (Table 1), which is consistent with the results of several authors who also found interactions between cotton genotypes and isolates of Ramularia. Rathaiah (1976) suggested that the aggressiveness of R. areola isolates is variable, and Cia et al (2013) observed variability in the pathogen from two different regions in Brazil. As observed by Pezenti et al (2013), the genotypes CNPA BA-2003-2059 and FMT 02102996 were susceptible when inoculated with isolates 13.2, 17.5 and 58.4 of R. areola; however, these genotypes showed resistance when inoculated with the other isolates.…”

Section: Discussionmentioning

confidence: 99%

“…According to Rathaiah (1976), Ramularia leaf spot must be managed, and varieties resistant to the pathogen are the cheapest and most efficient method for disease control. Cia et al (2009) evaluated 18 cotton genotypes; 61% of the genotypes were moderately or highly susceptible and 29% were moderately resistant to Ramularia. In glasshouse conditions, Zandon a et al (2012) found that a single dominant gene governed the resistance to R. areola strain 44 in the genotypes CNPA BA 2003e2059 and FMT 02102996.…”

Section: Introductionmentioning

confidence: 99%

Management of Ramularia leaf spot on cotton using integrated control with genotypes, a fungicide and Trichoderma asperellum

2017

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Ramularia leaf spot, caused by Ramularia areola, is responsible for premature defoliation of cotton, resulting in potential reductions in yield. The objective of this study was to evaluate integrated control using genotypes, a fungicide and Trichoderma asperellum to manage Ramularia leaf spot on cotton. In the greenhouse, the resistance of eighteen genotypes was evaluated with two isolates of R. areola (IMA 244 and IMA 237). In field, the severity of Ramularia leaf spot was evaluated on cotton genotypes CNPA MT 2009-1381, CNPA GO 2007-419, BRS 293, BRS 372, CNPA GO 2008-1265 and FMT 701 treated or untreated with a fungicide in Primavera do Leste, MT, Correntina, BA, and Santa Helena de Goi as, GO, during the 2011e2012 season. The varieties BRS 293 and BRS 372 were sprayed with a fungicide or Trichoderma in Sapezal, MT, during the 2012e2013 season, and the disease severity and fiber yield were evaluated. Significant interactions were detected between Ramularia isolates and cotton genotypes; the lowest disease severity was observed with IMA CD 05e8276 and CNPA GO 2007-419 genotypes. In the field tests, the lowest disease severity was with variety BRS 372 and the highest was with BRS 293, when grown in two different regions. The chemical fungicide and T. asperellum both reduced the disease severity in cotton varieties BRS 372 and BRS 293; however, yields were not significantly affected. In conclusion, an integrated strategy with the management tools of resistant varieties, fungicides and biocontrol agents should be used to control Ramularia leaf spot on cotton.

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“…RLS can be controlled through crop rotation, balanced fertilization, genetic resistance, controlling seeding season, cultural management and fungicide application (CHITARRA et al, 2005;ROCHA;CARVALHO;OLIVEIRA, 2005;SUASSUNA et al, 2008). Genetic resistance is the most economical and efficient form of control, however, most cultivars currently used present medium to high susceptibility to the disease (CIA et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Ramularia leaf spot effect on yield and fiber quality of cotton submitted to fungicide application

Tormen¹,

Blum

2019

Rev. Caatinga

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Ramularia leaf spot (RLS) is the major cotton disease in Brazil and one of the main causes of crop yield reduction. The disease causes defoliation reduces photosynthetic capacity and causes premature opening of bolls. Due to the impact of RLS on the production of Brazilian cotton and the lack of scientific publications investigating the disease, the present work aims to evaluate the efficiency of fungicides in controlling disease and their impact on yield and fiber quality. Three field experiments were carried out during the 2014/2015 and 2016/2017 seasons in Planaltina, Federal District and Cristalina, Goiás. Experiments followed a randomized complete block design (4 blocks) and treatments consisted of the application of fungicides, plus a non-treated plot. The fungicide applications began preventively and were repeated every 14 days until six sprays had been completed. Severity of RLS was assessed and used to calculate the area under disease progress curve (AUDPC). Yield and cotton fiber quality were also evaluated. All fungicides had reduced AUDPC and obtained higher cotton yields in relation to the non-treated plot. Strobilurin-group fungicides (azoxystrobin, pyraclostrobin and picoxystrobin) showed low effectiveness when sprayed alone. The demethylation inhibitor fungicides (difenoconazole, epoxiconazol, tetraconazol and metconazole) were more effective than the strobilurins. The highest efficiency rates were achieved by application of pyraclostrobin + fluxapyroxad, pyraclostrobin + epoxiconazole + fluxapyroxad and fentin hydroxide. Disease severity affected cotton yield, causing losses from 14.8% to 31.7%. Resultant reductions in cotton fiber quality negatively affect the micronaire composition, altering the length, strength and uniformity of fibers.

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Reação de genótipos de algodoeiro à mancha de Ramularia em diferentes épocas e ambientes

Cited by 10 publications

References 0 publications

Severity of Ramularia Leaf Spot and Seed Cotton Yield in Different Sowing Times

Severity of Ramularia Leaf Spot and Seed Cotton Yield in Different Sowing Times

Management of Ramularia leaf spot on cotton using integrated control with genotypes, a fungicide and Trichoderma asperellum

Ramularia leaf spot effect on yield and fiber quality of cotton submitted to fungicide application

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