Subjective components of mildew assessment on spring barley

Newton, A. C.; Hackett, Christine A.

doi:10.1007/bf01874807

Cited by 61 publications

(45 citation statements)

References 21 publications

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“…Os avaliadores tiveram uma tendência em superestimar a severidade da doença, a qual tem sido observada em vários outros estudos envolvendo validação de escalas (NEWTON & HACKETT, 1994;PARKER et al, 1995;DIAZ et al, 2001; LEITE & AMORIM, 2002;CAPUCHO et al, 2010;CAPUCHO et al, 2011;RIOS et al, 2013). Apenas em alguns poucos estudos tem sido verificada a severidade subestimada (MICHEREFF et al, 1998(MICHEREFF et al, , 2000GOMES et al, 2004).…”

Section: Discussionunclassified

Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

et al. 2015

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RESUMO Objetivou-se propor e validar uma escala diagramática para quantificar a antracnose do colmo em milho. A severidade da antracnose foi estimada por dez avaliadores sem o uso de escala em 139 entrenós, e os mesmos avaliadores avaliaram os entrenós usando uma escala publicada anteriormente na literatura (primeira escala) e uma nova escala proposta. Com o uso da escala proposta, todas as variáveis foram significativamentediferentes em relação à primeira escala, e os valores foram mais próximos de uma medição acurada (r=0,97, C b =0.98, u=0.09, υ=1.06, ρ c =0.96 INTRODUÇÃOA antracnose do colmo Colletotrichum graminicola (Ces.) Wils é uma das doenças mais importantes na cultura do milho em vários países, causando acamamento das plantas, redução na produção e qualidade dos grãos (BERGSTROM & NICHOLSON, 1999;COTA et al., 2012;MATIELLO et al., 2013). Os sintomas da antracnose do colmo são mais visíveis após o florescimento das plantas de milho, porém o processo infeccioso inicia-se pelos propágulos provenientes das lesões foliares ou daqueles presentes em restos culturais. Na casca, surgem lesões estreitras, longitudinais e com aspecto encharcado, que são inicialmente de coloração pardo-avermelhada, posteriormente tornando-se marromescuras a negras. Nos tecidos internos do colmo, ocorre uma coloração marrom-escura, que entra em processo de desintegração, afetando o fluxo de água e nutrientes do colmo para a parte superior, podendo ocasionar a morte prematura e o acamamento das plantas (KELLER &

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Section: Discussionunclassified

Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

et al. 2015

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“…The results of any assessment will vary according to an individual's experience. Furthermore, Mahlein [8] argues that the decision can be affected by temporal variation, as well as those incurred from different assessors [8][9][10][11]. An objective technique to assess PRR disease severity in tree canopies is highly desirable.…”

Section: Visual Interpretation Of Canopy Ciba-geigy Simpsonmentioning

confidence: 99%

“…2018, 10 Author Contributions: All the authors jointly conceived and designed the experiments; A.S.A.S. performed the field work with the contribution of C.W.S.…”

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Quantifying the Severity of Phytophthora Root Rot Disease in Avocado Trees Using Image Analysis

et al. 2018

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Phytophthora root rot (PRR) infects the roots of avocado trees, resulting in reduced uptake of water and nutrients, canopy decline, defoliation, and, eventually, tree mortality. Typically, the severity of PRR disease (proportion of canopy decline) is assessed by visually comparing the canopy health of infected trees to a standardised set of photographs and a corresponding disease rating. Although this visual method provides some indication of the spatial variability of PRR disease across orchards, the accuracy and repeatability of the ranking is influenced by the experience of the assessor, the visibility of tree canopies, and the timing of the assessment. This study evaluates two image analysis methods that may serve as surrogates to the visual assessment of canopy decline in large avocado orchards. A smartphone camera was used to collect red, green, and blue (RGB) colour images of individual trees with varying degrees of canopy decline, with the digital photographs then analysed to derive a canopy porosity percentage using a combination of 'Canny edge detection' and 'Otsu's' methods. Coinciding with the on-ground measure of canopy porosity, the canopy reflectance characteristics of the sampled trees measured by high resolution Worldview-3 (WV-3) satellite imagery was also correlated against the observed disease severity rankings. Canopy porosity values (ranging from 20-70%) derived from RGB images were found to be significantly different for most disease rankings (p < 0.05) and correlated well (R 2 = 0.89) with the differentiation of three disease severity levels identified to be optimal. From the WV-3 imagery, a multivariate stepwise regression of 18 structural and pigment-based vegetation indices found the simplified ratio vegetation index (SRVI) to be strongly correlated (R 2 = 0.96) with the disease rankings of PRR disease severity, with the differentiation of four levels of severity found to be optimal.

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“…However, the absence of 522 strong associations between positions of major ver-523 nalistation/flowering time loci and those of resistance 524 QTL suggests that it is not growth habit per se that 525 affects resistance, but rather that desirable resistance 526 characters are associated with winter barley types. 527 This would appear to validate the use of winter 9 The standard error associated with the estimated QTL effect is shown in parentheses a Plot disease score at GS50 measured on 1-9 scale (Newton and Hackett 1994) and normalized using a natural logarithmic transformation b Amount of R. secalis DNA at GS50 measured in pg c Relative disease expression at GS50, defined as the residuals from a SMA regression fitting the effect of the amount of R. secalis DNA on area of visual disease symptoms …”

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Genetic basis of control of Rhynchosporium secalis infection and symptom expression in barley

et al. 2011

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10 Abstract The genetic basis of several different 11 components of resistance to Rhynchosporium secalis 12 in barley was investigated in a mapping population 13 derived from a cross between winter and spring 14 barley types. 34Rhynchosporum secalis (Oudem) J.J. Davis, the 35 pathogen that causes 'rhynchosporium', 'barley leaf 36 blotch ' or 'scald', in Hordeum vulgare L. (barley). is 37 one of the most economically important barley 38 pathogens worldwide, particularly in cool humid 39 environments, causing reductions in both yield and 40 grain quality (Zhan et al. 2008). Average yield losses 41 (from Canada) have been estimated at 5-10% (Tur-42 kington et al. 1998), though losses of up to 40% have 43 been reported under conditions favourable for the 44 disease (Xi et al. 2000). Mapping studies have located 45 a number of major resistance (R) genes and quanti-46 tative trait loci (QTL) affecting expression of resis-47 tance to R. secalis; these are predominantly located 48 on barley chromosomes 2H, 3H and 7H (Zhan et al. 49 2008). Whilst current control strategies in the UK 50 frequently include a fungicide treatment, commercial 51 cultivars with good levels of resistance, probably due ; it has been the main winter barley malting culti-166 var grown by farmers over this period. It was initially 167 rated as having a good resistance to R. secalis,b e i n g 168 rated '8', on a 1-9 scale of increasing host resistance as 169 described in the recommended list protocols (www. 170 hgca.com). Leonie originally had the best rating of '9,' 171 but its resistance rating had declined to '5.9' by 2010 172 (www.hgca.com). Cv Cocktail was first recommended 173 for cultivation in the UK in 2003 and was formerly an 174 accepted spring barley malting cultivar in the UK. It 175 does not possess either of the two R genes for resistance 176 to R. secalis found in current UK spring barley cultivars 177 and had a moderate resistance rating of '5' when first 178 recommended, which had increased slightly to '5.9' in 179 the 2010 recommended list (www.hgca.com). 180 WB05-13 was bred to combine the resistance to 181 R.secalis and BaYMV-1 of Leonie with the accepted 182 malting quality attributes of Pearl; thus progeny from 183 its cross with Cocktail are expected to segregate for 184 resistance to R. secalis and to BaYMV-1 as well as 185 for the sdw1 dwarfing gene found in Cocktail. In 186 addition, WB05-13 has the Vrs1.t allele at the VRS1 187 locus on chromosome 2H and the mapping popula-188 tion therefore also segregates for the deficiens ear 189 type. Over 800 individual plants were derived from 190 microspore culture of the F 1 progeny; 550 lines were 191 fertile and produced sufficient seed for a field 192 multiplication plot that was sown at the James Hutton 44Author Proof (2007/2008 and 2008/2009) at the 271 James Hutton Institute rhynchosporium disease nurs-272 ery (Table 1). Cocktail, Leonie and Pearl together 273 with seven other controls were included in the trial to 274 give a trial with 200 entries. Field trials were...

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Subjective components of mildew assessment on spring barley

Cited by 61 publications

References 21 publications

Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

Quantifying the Severity of Phytophthora Root Rot Disease in Avocado Trees Using Image Analysis

Genetic basis of control of Rhynchosporium secalis infection and symptom expression in barley

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