Thresholds for control of <i>Septoria</i> spp. in winter wheat based on precipitation and growth stage

Hansen, J. G.; Secher, B. J. M.; Jørgensen, Lise Nistrup; Welling, B.

doi:10.1111/j.1365-3059.1994.tb00569.x

Cited by 35 publications

(20 citation statements)

References 11 publications

(11 reference statements)

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“…Hansen et al (1994) encontraron una buena correlación entre la severidad de S. tritici y la frecuencia de días con más de 1 mm de lluvia durante 1 mes, comenzando en el estado fenológico de encañazón. En Argentina, Moschini (2007) halló una fuerte correlación entre la frecuencia de días con precipitaciones mayores a 7 mm y el coeficiente de infección de S. tritici, confirmando que a partir de dicho umbral (7 mm), es probable contar con la energía gravitacional y el mojado adecuados para la remoción y dispersión de las esporas de Septoria.…”

Section: Discussionunclassified

Relación entre la precipitación registrada en estados reproductivos de la soja y la severidad de Septoria glycines y Cercospora kikuchii

Carmona

Moschini

Cazenave

et al. 2010

Trop. plant pathol.

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RESUMENDurante los años 2003 a 2008 se evaluó la severidad de las enfermedades de fin de ciclo (SevEFC, mancha marrón y tizón morado) en el estado fenológico R7 en localidades de las provincias de Santa Fe y Córdoba. Los valores de SevEFC (N=15) se categorizaron binariamente en función de un valor umbral en: epidemia severa (Sev EFC>36 %) y epidemia moderada a ligera (<=36 %). La variación de la SevEFC en R7 fue analizada en relación a variables ligadas a la precipitación, procesadas entre R3 y R5. Las variables se expresaron como frecuencia y precipitación acumulada en mm, que superan los umbrales: 1, 5, 7 y 10 mm. Las variables DPr7 (días con precipitación >7 mm), PrAc7 (acumulado de precipitaciones diarias >7 mm) y la interacción entre ambas (It7) resultaron ser las más fuertemente correlacionadas con los niveles epidémicos (coeficiente de Kendall Tau-b (r K = 0,74, 0,60 y 0,71 respectivamente). El modelo de regresión logística que incluyó a PrAc7 estimó correctamente la probabilidad de ocurrencia en 12 de las 15 observaciones de SevEFC. Los modelos logísticos que integraron las variables DPr7 o It7, obtuvieron precisiones de predicción de 93,3 %. Estos resultados podrían ser útiles para la predicción y control de las EFC. Palabras clave: Glycine max, enfermedades de fin de ciclo, modelos logísticos. were recorded at the R7 growth stage at several sites in Santa Fe and Córdoba Provinces. The annual LSDsev records (N=15) were grouped into two epidemic categories based on a threshold value (median of observed disease data): severe (LSDsev >36 %) and moderate to light (LSDsev <=36 %). Variations in epidemic levels were studied in relation to precipitation-based variables, processed in a time window limited by R3 and R5 growth stages. The variables were expressed as frequency (days) and total accumulation (mm) of daily precipitations greater than the thresholds 1, 5, 7 and 10 mm. The variables PrF7 (number of days with precipitations>7 mm) and AcPr7 (total accumulation of daily precipitations >7 mm) and the interaction (product) between them (It7) were the most strongly correlated, according to Kendall tau-b coefficients (r K =0.74, 0.60 and 0.71 respectively). Logistic regression model including AcPr7 correctly estimated the probability of occurrence of epidemic categories in 12 cases (out of 15). Logistic models integrating PrF7 or the interaction effect (It7) presented prediction accuracies of 93.3 %. These results could be useful for prediction and chemical control of LSD. Keywords: Glycine max, late season diseases, logistic models. logistic models. logistic models. ABSTRACT INTRODUCCIÓNDurante la campaña 2008/09, la Argentina alcanzó una siembra record de 17 millones de hectáreas de soja, constituyéndose en la mayor superficie sembrada en la historia del país con una única especie (SAGPyA, 2008). Casi la totalidad de la siembra correspondió a cultivares modificados genéticamente y la mayor parte se cultiva bajo siembra directa (SD). Este proceso de crecimiento estuvo acompañado por el avance de la frontera ...

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Section: Discussionunclassified

Relación entre la precipitación registrada en estados reproductivos de la soja y la severidad de Septoria glycines y Cercospora kikuchii

Carmona

Moschini

Cazenave

et al. 2010

Trop. plant pathol.

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“…Heavy rainfall during this period may cause lodging, which will reduce harvested yield (Easson et al 1993). It is, however, more likely that the negative effect of precipitation in July on yields are caused by Septoria disease, which is favoured by wet conditions during this period (Hansen et al 1994). Fig.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of field-scale winter wheat production in Denmark to climate variability and climate change

Olesen¹,

Jensen²,

Petersen³

2000

Clim. Res.

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A simulation model of the direct effects of climate on winter wheat production and grain yield is presented. The model was calibrated using data from field experiments in Denmark. The model was validated using data from near optimally managed experimental plots with winter wheat from The Netherlands and Denmark. The model was further evaluated using data from 1971 to 1997 for 7 sites in Denmark. The model explained from 0 to 20% of the variation in detrended observed yields, depending on soil type. A regression analysis of observed yields against monthly climate data showed a positive effect of temperature in October, November and January on grain yield, a positive effect of radiation in April and a strongly negative effect of precipitation in July. Only the positive effect of radiation in April was predicted by the simulation model, probably because the indirect effects of climate are not taken into account by the model (e.g. effects of rainfall on lodging or Septoria disease). The sensitivity of simulated grain yield to changes in mean temperature, temperature variability, precipitation, length of dry spells and CO 2 concentration was analysed for 4 soil types using generated climate data from 1 site in Denmark. Yield decreased with increasing temperature. This decrease was strongly non-linear with temperature change when using a fixed sowing date, but almost linear for the optimal sowing date. There was only a very small response to changes in temperature variability. Increasing precipitation increased yields with the largest response on the sandy soils. Large changes in grain yield were also seen on sandy soils with changes in the length of dry spells. A comparison of the simulated responses to the direct effects of temperature and rainfall with those to the indirect effects of these variables as estimated from the regression analysis showed that the indirect and the direct effects had opposite effects and that they may almost cancel each other out. The simulated increase in grain yield due to increasing CO 2 concentration in most cases exceeded the simulated responses to changes in climate variables.

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“…This is because they assume, tacitly or by implication, that the main risk of infection to the upper leaf layers comes from inoculum that developed on leaves during winter and spring, before stem extension (e.g. Anonymous, 1986;Hansen et al, 1994). Previously, Bahat et al (1980) reported a ladder effect of disease progression that was affected by the distances between consecutive leaves.…”

Section: Discussionmentioning

confidence: 99%

**Influence of crop growth and structure on the risk of epidemics by Mycosphaerella graminicola (Septoria tritici) in winter wheat**

et al. 1997

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Generally, it is recognized that inocula of Septoria tritici present on the basal leaves of winter wheat crops are spread towards the top of the canopy by splashy rainfall. This mechanism of inoculum dispersal is commonly accepted to be a key limit on disease progression. Therefore, attempts to forecast epidemics of S. tritici often quantify rainfall by some means, but largely ignore measurement of pathogen and host variables. In the present study, we show that new wheat leaves emerge initially at a height below established leaves that can contain sporulating lesions of S. tritici. This presents the possibility of horizontal inoculum transfer, even without splashy rainfall. The extent and duration of overlap between emergent and established leaves was found to differ considerably with cultivar and sowing date. Nitrogen application had little effect on overlap, because differences in crop phenology, e.g. leaf area and nodal length, were relative. However, estimates of raindrop penetration to the base of crop canopies suggested that vertical movement of inoculum is affected by nitrogen application. Crops receiving more nitrogen are denser, and therefore less rainfall reaches the base of the canopy. The interactions between crop and pathogen development are discussed with reference to the implications for predicting disease risk. In particular, cultivar traits that promote disease escape are quantified.

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Thresholds for control of Septoria spp. in winter wheat based on precipitation and growth stage

Cited by 35 publications

References 11 publications

Relación entre la precipitación registrada en estados reproductivos de la soja y la severidad de Septoria glycines y Cercospora kikuchii

Relación entre la precipitación registrada en estados reproductivos de la soja y la severidad de Septoria glycines y Cercospora kikuchii

Sensitivity of field-scale winter wheat production in Denmark to climate variability and climate change

**Influence of crop growth and structure on the risk of epidemics by Mycosphaerella graminicola (Septoria tritici) in winter wheat**

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