Fig 1.
Relational diagram of the model simulating the life cycle of Botrytis cinerea.
Legend: boxes are state variables; line arrows show fluxes and direction of changes; valves define rates regulating these fluxes; diamonds show switches (i.e., conditions that open or close a flux); circles crossed by a line show parameters and external variables; dotted arrows show fluxes and direction of information from external variables to rates; circles are intermediate variables; clouds indicate outgoing variables. See Table 1 for acronym explanations.
Table 1.
List of variables, rates, and parameters used in the model describing the life cycle of Botrytis cinerea on grapevines.
Table 2.
Summary characteristics (location, year, cultivar, and training system) of the vineyards used for validation of the Botrytis cinerea model. Also indicated are the observed incidence and severity of Botrytis bunch at maturity and the classification of the epidemics.
Fig 2.
Weather data and model output at Conselice in 2010 (CO-10).
A: daily data of temperature (red line, T in °C), relative humidity (green line, RH in %), rain (blue bars, in mm), and wetness duration (light blue area, WD in hours); B: predicted rate of spore production (SPOR) by Botrytis cinerea; C: predicted relative infection severity (RIS) on inflorescences and young clusters by conidia (RIS1; green bars) during the first infection period (green area), and on ripening berries by conidia (RIS2; blue bars) and mycelium (berry-to-berry infection) (RIS3; red bars) during the second infection period (orange area). Lines indicate the accumulated values of RIS1 (SEV1; green line) and of RIS2+RIS3 (SEV2+SEV3; purple line). Numbers in C indicate vine growth stages of full flowering (stage 65 of the scale of Lorenz et al. [31]), fruit set (stage 71), and berries developing (stage 83). The first infection window extends from inflorescences clearly visible” (stage 53) to “berries groat-sized, bunches begin to hang” (stage 73). The second infection window extends from “majority of berries touching” (stage 79) to “berries are ripe for harvest” (stage 89).
Fig 3.
Weather data and model output at S. Michelle in 2012 (SM-12).
A: daily data of temperature (red line, T in °C), relative humidity (green line, RH in %), rain (blue bars, in mm), and wetness duration (light blue area, WD in hours); B: predicted rate of spore production (SPOR) by Botrytis cinerea; C: predicted relative infection severity (RIS) on inflorescences and young clusters by conidia (RIS1; green bars) during the first infection period (green area), and on ripening berries by conidia (RIS2; blue bars) and mycelium (berry-to-berry infection) (RIS3; red bars) during the second infection period (orange area). Lines indicate the accumulated value of RIS1 (SEV1; green line) and of RIS2+RIS3 (SEV2+SEV3; purple line). Numbers in C indicate vine growth stages of full flowering (stage 65 of the scale of Lorenz et al. [31]), fruit set (stage 71), and berries developing (stage 83). The first infection window extends from “inflorescences clearly visible” (stage 53) to “berries groat-sized, bunches begin to hang” (stage 73). The second infection window extends from “majority of berries touching” (stage 79) to “berries are ripe for harvest” (stage 89).
Fig 4.
Model output (i.e., SEV1, SEV2, and SEV3) for 21 Botrytis cinerea epidemics.
The 21 epidemics are coded as in Table 2; their symbols (dots) are green, orange or red based on Botrytis bunch rot incidence and severity as indicated in Table 2 (green, orange, and red indicate mild, intermediate, and severe epidemics, respectively). Triangles represent the average of each group. SEV1 = relative severity of the infections caused by conidia and accumulated over the first infection period (“inflorescences clearly visible” to “berries groat-sized, bunches begin to hang”); SEV2 = relative severity of the infections caused by conidia and accumulated over the second infection period (“majority of berries touching” to “berries are ripe for harvest”); and SEV3 = relative severity of the infections caused by mycelium (berry-to-berry infection) and accumulated over the second infection period.
Table 3.
Grouping of 21 Botrytis cinerea epidemics based on disease assessment in vineyards and as predicted based on the discriminant function analysis (DFA) using model output as discriminant variables.
Fig 5.
Assignment of 21 Botrytis cinerea epidemics to three severity groups based on the discriminant function analysis.
The 21 epidemics are coded as in Table 2; the color of the code indicates the severity of Botrytis bunch rot as assessed in the vineyard at harvest (see Table 2). The color of the dot indicates group assignment based on DFA. For both codes and dots, green, orange, and red indicate mild, intermediate, and severe epidemics, respectively. Crosses represent the centroids of each group based on DFA. Coefficients of the canonical discriminant functions are shown in Table 6.
Table 4.
Statistics of the discriminant function analysis used to classify 21 Botrytis cinerea epidemics based on model output.
Table 5.
Significance of the discriminant function analysis used to classify 21 Botrytis cinerea epidemics based on model output.
Table 6.
Coefficients for each discriminant variable in each canonical function (F1 or F2) obtained in the discriminant analysis used to classify 21 Botrytis cinerea epidemics based on model output.
Fig 6.
Assignment of 21 Botrytis cinerea epidemics to mild, intermediate, and severe groups based on model output.
Discriminant function analysis (DFA) was calculated daily between “inflorescences clearly visible” (growth stage 53 of Lorenz et al. [31]) and “berries ripe for harvest” (stage 89). The colors of the 21 horizontal bars indicate the daily assignment to epidemic groups based on DFA. The 21 epidemics are also coded on the left of each horizontal bar based on the severity of Botrytis bunch rot as observed in the vineyard at harvest and as indicated in Table 2. For both codes and bars, green, orange, and red indicate mild, intermediate, and severe epidemics, respectively. For example, the epidemic at BAG-12 was severe at harvest based on observation and progressed from mild to intermediate to severe based on DFA. Numbers in bars indicate the critical growth stages for fungicide applications; end of flowering (stage 69); pre-bunch closure (stage 77); veraison (stage 83).