Development and validation of a diagrammatic scale for quantifying maize leaf spots caused by Diplodia macrospora

Lorenzetti, Eloísa; Tartaro, Juliano; Neto, Alfredo José Alves; Heling, Anderson Luis; Carvalho, Jeferson Carlos; Stangarlin, José Renato; Kuhn, Odair José; Portz, Roberto Luis

doi:10.5433/1679-0359.2019v40n6p2475

Cited by 4 publications

(4 citation statements)

References 15 publications

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“…- 30%. With the scale five evaluators were outside the range of -10 to 10, two of them (15.38% of the total evaluators) with errors between 15 and 20%, similar results were found in previous studies (SANTOS et al, 2017;TROJAN et al, 2018;LORENZETTI et al, 2019). Therefore, eight evaluators can be considered good in the assessment of the disease when using the scale (LIMA et al, 2013;NUÑEZ et al, 2017).…”

Section: Discussionsupporting

confidence: 85%

“…Regarding the t-test for the values of the intercept (a), the null hypothesis was rejected in more cases when the scale was not used, with the scale accepted values increased in a 20%. R 2 values improved when the scale was used, the R 2 average showed an increase of 3.16% compared with the value obtained without the scale, in both cases the evaluation of severity showed good precision, the values of R 2 were ≥0.85, considered high for this type of estimate (LIMA et al, 2013;TROJAN et al, 2018;LORENZETTI et al, 2019).…”

Section: Discussionmentioning

confidence: 88%

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Diagrammatic scale for measuring severity of gray mould in thornless Castilla blackberry (Rubus glaucus Benth)

2020

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Gray mould, caused by the fungus Botrytis cinerea Pers., is a disease that largely affects the crops of Rubus glaucus Benth. (Castilla blackberry) in Colombia. In spite of the economic losses that it causes in the production of Castilla blackberry at national level, a standardized method to quantify the disease severity caused by this fungus in the fruits has not yet been reported. In the present work, a diagrammatic scale was prepared to assess gray mould severity in thornless fruits of R. glaucus. The proposed scale showed the levels of 5, 10, 20, 40, 60, 80, and 100%. Photographic images were obtained for each of these levels, which were processed using the ImageJ software. The scale was validated by 13 evaluators who assessed affected fruits with and without the scale. The precision and accuracy of each evaluator was determined by simple linear regression between actual and estimated severity. The evaluators showed better precision, accuracy, and reproducibility in the assessments performed with the scale. The proposed scale is appropriate to estimate the severity of gray mould in R. glaucus fruits.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 88%

Diagrammatic scale for measuring severity of gray mould in thornless Castilla blackberry (Rubus glaucus Benth)

2020

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“…SADs have been widely used as a tool to improve visual severity estimation of several foliar diseases in different crops (Del Ponte et al., 2017). For foliar corn diseases, the SADs have also improved visual estimates for eyespot (Camochena et al., 2008), white spot (Capucho et al., 2010; Malagi et al., 2011; Sachs et al., 2011), northern leaf blight (Lazaroto et al., 2012), diplodia leaf streak (Lorenzetti et al., 2019) and bacterial leaf streak (Braga et al., 2020) in field for adult plants. However, to our knowledge, no SADs had been developed to evaluate the severity of GLS in corn leaves.…”

Section: Discussionmentioning

confidence: 99%

Development and validation of a standard area diagram set to assess corn grey leaf spot severity and foliar fungicide control efficacy

Rocha,

Custódio,

Fantin

et al. 2024

Journal of Phytopathology

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Grey leaf spot (GLS), caused by Cercospora spp., has become a very important foliar disease for second‐crop corn season, mainly in South America. Therefore, this study aimed to develop and validate a standard area diagram set (SADs) to estimate the severity of GLS and to apply the SADs established in this study to evaluate the efficacy of fungicides for GLS control in field trials. The SADs with nine levels of severity (0.5; 2; 5; 10; 20; 30; 40; 50 and 60%) improved accuracy, precision and reliability. To evaluate the control of GLS in corn, two experiments spraying chemical fungicides were conducted, one in Rio Verde (GO) (experiment A) and another in Chapadão do Sul (MS) (experiment B). Both experiments were conducted in randomized block design, with 10 treatments and four replicates. For the severity assessment, the SADs elaborated in this study was used. From this severity data over time, disease progress curves, area under the disease progress curve (AUDPC), and yield were obtained. Based on the AUDPC and yield values, all treatments differed from the control. The fungicide fluxapyroxad + pyraclostrobin + mefentrifluconazole had the highest value, giving 72.8% control efficacy and the highest yield maintenance of 43.5%. The other treatments had an intermediate control efficacy and yield. The SADs proposed here is a useful tool for improving visual assessments of GLS severity on corn leaves and fungicides can be used for integrated disease management.

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“…), and is more common for maize grown under warm and humid conditions of tropical and subtropical regions (Wordell Filho, Casa, & Nesi, 2016;Mário, Gozuen, & Juliatti, 2017). The ideal conditions for conidia germination are relative humidity over 50% and temperatures between 25 and 32°C (Lorenzetti et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Macrospora leaf spot development conditions and resistance/tolerance of Brazilian commercially grown maize genotypes

Wordell Filho,

Ducatti,

Nesi

2023

Acta Sci. Agron.

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Macrospora leaf spot (MLS), caused by the fungus Stenocarpella macrospora, is one of the most important diseases affecting maize in Brazil. However, there are no MLS-resistant cultivars commercially available. Therefore, this study aimed to investigate the lesion expansion rate of MLS in four maize genotypes, leaf wetness duration (0-, 6-, 12-, 18-, 24-, 30-, 36-, 42-, and 54-hour post-inoculation), disease development severity in three maize genotypes, and resistance/tolerance levels to MLS in 141 maize genotypes commercially grown in Brazil. The estimates were performed using logistic models adjusted to the parameters analyzed, except for resistance/tolerance levels, which were analyzed using proposed severity and resistance scales. The experiment was carried out at the Laboratory of Plant Phytopathology of the Epagri/Cepaf, Santa Catarina State, Brazil, from 2016 to 2020. Disease resistance was significantly different among genotypes and fungal isolates. However, none of the genotypes showed resistance or high tolerance levels to MLS. Leaf wetness duration influenced maximum disease severity, and lesion expansion rate differed significantly among the genotypes tested. All information generated in this study is essential for breeding programs of maize for MLS resistance

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Development and validation of a diagrammatic scale for quantifying maize leaf spots caused by Diplodia macrospora

Cited by 4 publications

References 15 publications

Diagrammatic scale for measuring severity of gray mould in thornless Castilla blackberry (Rubus glaucus Benth)

Diagrammatic scale for measuring severity of gray mould in thornless Castilla blackberry (Rubus glaucus Benth)

Development and validation of a standard area diagram set to assess corn grey leaf spot severity and foliar fungicide control efficacy

Macrospora leaf spot development conditions and resistance/tolerance of Brazilian commercially grown maize genotypes

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