Microscopia eletrônica de varredura do processo infeccioso de Ramularia areola em folhas de algodoeiro

Curvêlo, Carmen Rosa Silva; Rodrigues, Fabrício Ávila; Berger, Paulo Geraldo; Rezende, Dalilla Carvalho

doi:10.1590/s1982-56762010000200006

Cited by 15 publications

(22 citation statements)

References 11 publications

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“…Curvêlo et al (2010) confirm these results, in a study on infectious process of R. areola on cotton leaves via scanning electron microscopy, they found that the penetration and colonization of cotton leaf tissue occurred via stomata, and stated that it is the main route of infection of various fungal pathogens.…”

Section: Resultsmentioning

confidence: 62%

“…The experiment was conducted in the experimental area of the Universidade do Estado de Mato Grosso (UNEMAT), Tangara da Serra Campus, Brazil (14°39'07"S, 57°26'02"W, and altitude of 440.0 m), which has average temperature of 24,4ºC, average annual precipitation of 1,500 mm and relative humidity ranging from 70 to 80% (DALLACORT et al, 2011). The soil of the area is classified as clayey Distroferric Red Latosol (EMBRAPA, 2013).…”

Section: Methodsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 62%

Section: Methodsmentioning

confidence: 99%

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

et al. 2016

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“…Ramularia spots, like most diseases, are influenced by climate, which is crucial to the pathogen development of this disease. Rathaiah (1977) and later Curvêlo et al (2010), studying the penetration of R. areola, observed that the highest germination of conidia occurred in the temperature range of 25-30°C and an air humidity above 80%, and that the greater penetration of the fungus occurred in the nighttime wetting cycle and daytime drying cycle. The authors also found that in the process of germination and penetration, the germ tube of this fungus tolerates up to 16 h of drying (humidity above 20%) for a few cycles and then returns to the process of germination and penetration.…”

Section: Resultsmentioning

confidence: 96%

Estimated damage caused by ramularia leaf spots on cotton

Gílio¹,

Araújo²,

Araújo³

et al. 2017

Afr. J. Agric. Res.

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The objectives of this study are to establish damage functions for the Ramularia areola pathosystem and characterize the damage in cultivars susceptible and resistant to it. The experiment was conducted in the city of Tangará da Serra in the 2012/2013 harvest season. The experimental design was randomized blocks with four replications in a factorial arrangement of four cultivars × four gradients. The plots were divided into two subplots (twin plots). The division I received fungicide applications at intervals of 15, 30 and 45 days and no applications to establish the gradients of the disease, and the division II received weekly applications of fungicide in order to be kept without the disease or at minimum levels. FiberMax 993, FMT 701, FMT 707 RX and IAC 25 RMD cultivars were used with different reactions to ramularia spots. Disease severity was weekly determined and used to calculate the area below the disease progress curve (ABDPC). In addition to area below the severity progress curve (ABSPC), the variables related to the following production components were obtained: seed cotton productivity, damage, percentage of damage to productivity, average number of bolls per plant, weight of one hundred seeds, percentage of fiber, and components related to fiber technological characteristics. Analyses of variance were conducted and data were adjusted by the linear integral model. The ABSPC variable showed a high relation with damage and percentage of damage to productivity. Estimates reached levels of up to 975.42 kg ha -1 , or 36.83%, of damage to productivity.

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“…Budding is a continuous process as observed in both the isolates on V8 juice-agar. According to Rathaiah,[11] [12] and Curvelo et al [13], conidia germinate from epical and basal cells. In our isolates other than germination from epical and basal cells, budding occurs from several cells of the spores.…”

Section: Resultsmentioning

confidence: 99%

Spore Types and Spore Production of <i>Ramularia areola</i> for Screening Cotton Germplasm for Resistance

Volponi¹,

Matos²,

Girotto³

et al. 2014

AJPS

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Spore production of Ramularia areola has always been a difficult task. Brazilian isolates of R. areola produce spores of variable size and shape. The typical spores are 3 septate, rarely 4 and 5 septate, together with abundant single celled oblong to round bodies-a phenomenon not reported earlier for R. areola. Budding of spores is a continuous process as observed in our isolates. By repeated culturing the pathogen either ceases to produce typical spores or loses its pathogenic character. To solve this problem, a technique was developed to produce large quantity of typical spores under laboratory conditions. Sporulating cultures produced on Petri plates containing V8 juice-agar were kept on the laboratory bench till they became dry and then stored at 5˚C for reisolation and/or for production of fresh inoculum. In such dried cultures spores remain viable for a period of over 12 months, and hence isolates of R. areola originated from different geographic regions can be maintained in sporulating form. Results of the present investigation would aid cotton breeders and pathologists in screening germplasm resistant to Ramularia and in other genetical studies under glasshouse conditions.

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Microscopia eletrônica de varredura do processo infeccioso de Ramularia areola em folhas de algodoeiro

Cited by 15 publications

References 11 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

Estimated damage caused by ramularia leaf spots on cotton

Spore Types and Spore Production of <i>Ramularia areola</i> for Screening Cotton Germplasm for Resistance

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Microscopia eletrônica de varredura do processo infeccioso de Ramularia areola em folhas de algodoeiro

Cited by 15 publications

References 11 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

Estimated damage caused by ramularia leaf spots on cotton

Spore Types and Spore Production of &lt;i&gt;Ramularia areola&lt;/i&gt; for Screening Cotton Germplasm for Resistance

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Spore Types and Spore Production of <i>Ramularia areola</i> for Screening Cotton Germplasm for Resistance