Leaf Area as a Factor in Disease Assessment

Lim, L. G.; Gaunt, R. E.

doi:10.1017/s0021859600040971

Cited by 20 publications

(16 citation statements)

References 10 publications

(10 reference statements)

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“…The arithmetic mean of disease severity, estimated from different leaves at different positions on the main stem may either underestimate or overestimate the actual disease severity. For example, early epidemics may have secondary effects on the subsequent leaf area which may be larger than the direct effects of disease itself at the later stage (Lim & Gaunt 1981). Disease measurements on a percentage basis do not indicate the loss of healthy foliage, their subsequent ability to capture solar radiation or the effects of this loss later in the crop growth.…”

Section: Discussionmentioning

confidence: 99%

Empirical models of the relationships between early blight(Alternaria solani)and yield of potato(Solanum tuberosum)crop grown under different production environments

Shah

McKenzie

Gaunt

et al. 2004

New Zealand Journal of Crop and Horticultural Science

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Four experiments were conducted over two growing seasons during 1995/96 and 1996/97 at Lincoln University and the New Zealand Institute for Crop & Food Research, Lincoln, Canterbury. A large database was used to assess the effects of production environments on disease yield relationships and to compare different models derived from pathogen-based disease measurement and host-based disease measurements. All the models were developed using regression analyses. All the single point (SP), multiple point (MP), and integral models derived from host-based disease measurements explained more variation than models derived from pathogenbased disease measurements. SP, MP, and integral models were also compared and integral models †Deceased. H03029; Online publication date 17 March 2004 Received 24 March 2003; accepted 17 October 2003were selected as the best for comparing disease effects as they combine the effect of disease over the whole growing season in one variable. Further, integral models were tested for the effect of different production environments on disease yield relationships. It was found that the nitrogen-altered production environments had no significant effect on disease yield relationships, whereas potato cyst nematode-altered production environments significantly affected the disease yield relationship. A single model was used for the disease yield relationship for nitrogen inputs, whereas separate disease yield relationships were used for each nematode level.

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Section: Discussionmentioning

confidence: 99%

Empirical models of the relationships between early blight(Alternaria solani)and yield of potato(Solanum tuberosum)crop grown under different production environments

Shah

McKenzie

Gaunt

et al. 2004

New Zealand Journal of Crop and Horticultural Science

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“…Thus, damage by mildew cannot be attributed to the radiation use efficiency only, as this effect is confounded with the interception of radiation during the season. A consequence of this effect is that if crop growth is analysed in relation to the cumulative amount of radiation intercepted Berger, 1987 andLim andGaunt, 1981), effects of diseases like mildew appear absent as small differences between the slopes of the relations are then hard to detect. To complete these analysis, the relation between the disease intensity and the total amount of radiation intercepted should be included.…”

Section: Discussionmentioning

confidence: 99%

Effects of powdery mildew and weather on winter wheat yield. 2. Effects of mildew epidemics

Daamen¹,

Jorritsma

1990

Netherlands Journal of Plant Pathology

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Wheat yield losses caused by powdery mildew were computed based on effects of the disease on leaf photosynthesis. Powdery mildew was introduced in a crop model of wheat by quantification of five parameters, taking the vertical and horizontal distribution of mildew in the crop into account. The most important parameters were those of the mildew intensity, the distribution of mildew in the crop, and the effect of mildew on assimilation at light saturation. Measured mildew epidemics in field experiments in three different years, were used to compute yield losses. Computed losses were compared to measured losses. On average, computed yield loss approached measured, but measured yield loss was underestimated, especially in early mildew epidemics due to the computation of partitioning and reallocation of assimilates. Other processes which may cause an underestimation arc described. The use of crop models as a method to upgrade disease management systems is discussed.

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“…A estimativa da produção por meio da duração da área fotossinteticamente ativa expressa uma relação com base fisiológica definida, por dar maior ênfase às características do hospedeiro (Lim & Gaunt, 1981), portanto, é menos empírica que a obtida com uso da severidade.…”

Section: Introductionunclassified

Doenças foliares, área verde sadia e peso de grãos em diferentes cultivares de trigo

Funck¹,

Fernandes²,

Pierobom³

2009

Agraria

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Doenças foliares, área verde sadia e peso de grãos em diferentes cultivares de trigo¹ RES UMOObjetivou-se com este estudo correlacionar a severidade das doenças foliares incidentes à duração da área verde fotossinteticamente ativa e ao peso de grãos de trigo. O experimento foi conduzido com as cultivares de trigo BR 23, Embrapa 16 e BRS 179, na área experimental da Embrapa -Centro Nacional de Pesquisa de Trigo, situado em Passo Fundo, Rio Grande do Sul. Cada cultivar foi semeada em duas faixas nos anos de 2003 e 2004. Em uma das faixas, um fungicida de amplo espectro foi pulverizado três vezes durante o ciclo da cultura para mantê-la livre de doenças foliares. As avaliações foram realizadas semanalmente em cinco plantas coletadas ao acaso em cada parcela e os dados foram submetidos à análise estatística pelo programa "R". Em 2003, houve diminuição no peso seco das partes vegetativas e forte correlação (r= 0,96) entre a duração da área verde e o peso de grãos, enquanto, em 2004, essa tendência não foi evidenciada, comprovando correlação moderada (r= 0,48) entre a duração da área verde e o peso dos grãos. A relação entre o peso das partes vegetativas e o peso dos grãos depende da intensidade das doenças foliares e, portanto, varia de ano para ano de acordo com as condições climáticas. Palavras-chave:Triticum aestivum L., fungicidas, rendimento do trigo Leaf diseases, healthy green area and kernel weight in different wheat cultivars AB S TR ACTThis paper aimed to find out correlations between the severities of incident leaf diseases, the duration of photosynthetic active green area and the weight of wheat grains. Wheat cultivars BR 23, Embrapa 16 and BRS 179 were used in the experiment, carried out in the experimental area of the Embrapa -Wheat Research National Center, in the municipality of Passo Fundo, Rio Grande do Sul state. Each cultivar was sown in two plots during the years of 2003 and 2004. In one of the plots, a large spectrum fungicide was sprayed three times during the crop vegetative cycle, to keep it free of leaf diseases. The evaluations were carried out weekly in five plants randomly collected in each plot. Data was submitted to statistical analysis using program "R". The results showed that, in 2003, the dry weight of the vegetative parts decreased, and a strong correlation (r= 0.96) was observed between the duration of the green area and the wheat grain weight. On the other hand, in 2004 this trend was not evidenced, showing a moderate correlation (r= 0.48) between the duration of the green area and the grain weight. The correlation between the weight of vegetative plant parts and the weight of grains depends on the leaf diseases intensity and, therefore, is variable according to the climatic conditions.

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Leaf Area as a Factor in Disease Assessment

Cited by 20 publications

References 10 publications

Empirical models of the relationships between early blight(Alternaria solani)and yield of potato(Solanum tuberosum)crop grown under different production environments

Empirical models of the relationships between early blight(Alternaria solani)and yield of potato(Solanum tuberosum)crop grown under different production environments

Effects of powdery mildew and weather on winter wheat yield. 2. Effects of mildew epidemics

Doenças foliares, área verde sadia e peso de grãos em diferentes cultivares de trigo

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