Evaluación de una regla de decisión para el manejo integrado de oidio en vides cv. Cabernet Sauvignon

51 p.Se realizó un estudio con el objetivo de evaluar de forma espacializada la incidencia y severidad de oídio bajo dos estrategias de control. Este ensayo se llevó a cabo en un cuartel vitícola del cv. Cabernet Sauvignon de 1,56 ha ubicado en la Estación Experimental Panguilemo, Talca (35°22.2’ S, 71°35.39’ W, 121 m.s.n.m.), durante la temporada 2009-2010. Las dos estrategias de control utilizadas fueron un manejo tradicional con aplicaciones calendarizadas y un manejo integrado de oídio utilizando una Regla de Decisión Fitosanitaria (RDF), basada en la fenología de la vid y en observaciones de terreno. Además se implementó un testigo sin aplicaciones fungicidas. Cada tratamiento se repitió cuatro veces en un diseño de bloques al azar, utilizando la pendiente como factor de bloqueo. Las distintas variables de desarrollo del oídio (incidencia y severidad) y de crecimiento vegetativo de la vid (largo de brote, peso de poda) fueron medidas en una grilla regular de 59 puntos. Los datos obtenidos fueron analizados mediante un análisis de varianza clásico y luego sometidos a un análisis cartográfico para determinar la estructura espacial de las distintas variables en estudio. Los resultados indican que no hubo diferencias significativas entre el manejo tradicional (9 aplicaciones) y la RDF (4 aplicaciones), lo que permite una reducción de hasta el 50% del número de aplicaciones fungicidas con respecto al manejo tradicional, favoreciendo una producción ambientalmente sustentable. El estudio espacializado indicó que la ntensidad del daño fue influenciada por el crecimiento vegetativo, por lo tanto, una reducción en la expresión vegetativa reduciría el desarrollo del oídio./ABSTRACT: A study was conducted to evaluate in a spatialized way, the incidence and severity of powdery mildew (Erisiphe necator) with two control strategies. The experiment was carried out in a 1.6 ha commercial Cabernet Sauvignon block located in Talca, Maule, Region of Chile (35°22.2’ S, 71°35.39’ W, 121 m.a.s.l.) during the 2009- 2010 growing season. The two control strategies were: (i) traditional management with scheduled applications and (ii) integrated management of powdery mildew using decision rules (RDF), based on the grapevine phenology and in-situ field observations. Also a control treatment without fungicide applications was used. Each treatment had four replicates implementing a randomized block design, using the slope as blocking factor. The different variables in the development of powdery mildew (incidence and severity) and grapevine vegetative growth (shoot length, pruning weight) were measured in a regular 59-points-grid. Data collected were analyzed through a classic variance analysis and then subjected to a cartographic analysis to determine the spatial structure of the variables studied. Results showed that there were no significant differences between the traditional management (9 applications) and the RDF (4 applications), which allows up to a 50% reduction in the number of fungicide applications regarding the traditional management, which favours an environmentally sustainable production. The spatial study indicated that the damage intensity was influenced by the vegetative growth; therefore, a reduction in the vegetative expression would reduce the development of powdery mildew. Key words: Powdery mildew, decision rules, precision agriculture, spatial variability

A Smart Crop Water Stress Index-Based IoT Solution for Precision Irrigation of Wine Grape

The Scholander-type pressure chamber to measure midday stem water potential (MSWP) has been widely used to schedule irrigation in commercial vineyards. However, the limited number of sites that can be evaluated using the pressure chamber makes it difficult to evaluate the spatial variability of vineyard water status. As an alternative, several authors have suggested using the crop water stress index (CWSI) based on low-cost thermal infrared (TIR) sensors to estimate the MSWP. Therefore, this study aimed to develop a low-cost wireless infrared sensor network (WISN) to monitor the spatial variability of MSWPs in a drip-irrigated Cabernet Sauvignon vineyard under two levels of water stress. For this study, the MLX90614 sensor was used to measure canopy temperature (Tc), and thus compute the CWSI. The results indicated that good performance of the MLX90614 infrared thermometers was observed under laboratory and vineyard conditions with root mean square error (RMSE) and mean absolute error (MAE) values being less than 1.0 °C. Finally, a good nonlinear correlation between the MSWP and CWSI (R2 = 0.72) was observed, allowing the development of intra-vineyard spatial variability maps of MSWP using the low-cost wireless infrared sensor network

How are vineyards management strategies and climate-related conditions affecting economic performance? A case study of Chilean wine grape growers

In wine grape production, growers decide between alternative management strategies of the vineyard that have direct consequences on competitiveness. Since on-farm competitiveness allows growers to remain in the industry, it has become a highly relevant issue for the viticultural sector and a better understanding is required of the factors affecting vineyards’ economic performance. The aim of this study is to evaluate the impact on the economic performance of four management strategies. The vineyards management strategies analyzed in this study were: a) training system (tendone vs. vertical structures), b) wine grape destination (reserve vs. varietal wines), c) irrigation method (pressurized vs. gravity irrigation), and d) mechanization in harvesting (mechanized vs. hand-picked). These vineyards’ strategies are of different scope and nature, some of them represent structural (fixed) decisions while others are more related to flexible (alternative) decisions. This study uses the case of Chile, a country that has experienced rapid development of its export-oriented wine industry in recent decades; between 1990 and 2015, vineyard plantations doubled, wine production increased fivefold, and wine export volume grew from 22 to 1,445 million liters. The data used in the study come from face-to-face interviews administered to 336 Chilean wine grape growers, which was complemented with climatic variables retrieved from Geographic Information Systems. The study area covers the O’Higgins and Maule regions in Central-South Chile (33° 50’ and 36° 33’ S, WGS84 datum), located in central Chile in the heart of the fruit and vineyard production (Figure 1). Combined, both regions comprise 73% of the national planted area of vineyards, distributed among three important valleys, from north to south: Rapel, Curicó, and Maule. The area under study has a temperate Mediterranean climate, characterized by a six-month dry season (Sept- Mar) and a rainy winter, with precipitation between 600 and 700 mm annually. The primary data used in this study was generated at the vineyard level, administering a georeferenced survey on-site to 436 wine grape growers between October 2014 and March 2015. This survey was restricted to vineyards from irrigated lands, growing at least one hectare. The sampling procedure consisted of a stratified random sample across 16 municipalities, where the number of surveys administered was determined depending on the relative number of vineyards in each municipality. The questionnaire administered to wine grape growers collected detailed economic and agronomic information for the main variety grown in the vineyard, such as planted area, yield, grape price, and (per hectare) intensity of use of inputs and labor. Growers were asked about the number of applications, doses, and unitary prices in the case of agrochemicals (i.e., fertilizers, herbicides, insecticides, fungicides, and acaricides) and the number of working days or agricultural machines/equipment in the case of labor (i.e., harvest, pruning/mooring, tipping of shoots, de-sprouting, canopy defoliation, physical weed control, and other labor), which were valued at fixed market prices. Regarding growers’ performance, the yield obtained by each grower was multiplied by the average grape price of the variety in the sample. A log-log regression model of total value product (TVP) for the main variety grown in the vineyard was estimated, using production factors, vineyards’ attributes, management strategies, and climate-related conditions as explanatory variables. An interesting contribution of this study is the identification of TVP functions for land, fertilizers, fungicides, other agrochemicals, labor, and the age of vines. Our results show that the training system has the most impact on TVP, where tendone-trained vineyards demonstrated 50% higher TVP than those vertically trained. Reserve quality production also has a positive effect on TVP, increasing it by 22% compared to vineyards producing varietal quality grapes. In contrast, the use of pressurized irrigation systems and mechanization in harvesting do not present a significant effect on TVP. The findings of this paper represent an advance in the understanding of the economic performance factors associated with wine grape growing and could serve to guide on-farm decisions and sectoral policies in pursuing the competitive development of wine grape growers

How are vineyards management strategies and climate-related conditions affecting economic performance? A case study of Chilean wine grape growers

In wine grape production, growers decide between alternative management strategies of the vineyard that have direct consequences on competitiveness. Since on-farm competitiveness allows growers to remain in the industry, it has become a highly relevant issue for the viticultural sector and a better understanding is required of the factors affecting vineyards’ economic performance. The aim of this study is to evaluate the impact on the economic performance of four management strategies. The vineyards management strategies analyzed in this study were: a) training system (tendone vs. vertical structures), b) wine grape destination (reserve vs. varietal wines), c) irrigation method (pressurized vs. gravity irrigation), and d) mechanization in harvesting (mechanized vs. hand-picked). These vineyards’ strategies are of different scope and nature, some of them represent structural (fixed) decisions while others are more related to flexible (alternative) decisions. This study uses the case of Chile, a country that has experienced rapid development of its export-oriented wine industry in recent decades; between 1990 and 2015, vineyard plantations doubled, wine production increased fivefold, and wine export volume grew from 22 to 1,445 million liters. The data used in the study come from face-to-face interviews administered to 336 Chilean wine grape growers, which was complemented with climatic variables retrieved from Geographic Information Systems. The study area covers the O’Higgins and Maule regions in Central-South Chile (33° 50’ and 36° 33’ S, WGS84 datum), located in central Chile in the heart of the fruit and vineyard production (Figure 1). Combined, both regions comprise 73% of the national planted area of vineyards, distributed among three important valleys, from north to south: Rapel, Curicó, and Maule. The area under study has a temperate Mediterranean climate, characterized by a six-month dry season (Sept- Mar) and a rainy winter, with precipitation between 600 and 700 mm annually. The primary data used in this study was generated at the vineyard level, administering a georeferenced survey on-site to 436 wine grape growers between October 2014 and March 2015. This survey was restricted to vineyards from irrigated lands, growing at least one hectare. The sampling procedure consisted of a stratified random sample across 16 municipalities, where the number of surveys administered was determined depending on the relative number of vineyards in each municipality. The questionnaire administered to wine grape growers collected detailed economic and agronomic information for the main variety grown in the vineyard, such as planted area, yield, grape price, and (per hectare) intensity of use of inputs and labor. Growers were asked about the number of applications, doses, and unitary prices in the case of agrochemicals (i.e., fertilizers, herbicides, insecticides, fungicides, and acaricides) and the number of working days or agricultural machines/equipment in the case of labor (i.e., harvest, pruning/mooring, tipping of shoots, de-sprouting, canopy defoliation, physical weed control, and other labor), which were valued at fixed market prices. Regarding growers’ performance, the yield obtained by each grower was multiplied by the average grape price of the variety in the sample. A log-log regression model of total value product (TVP) for the main variety grown in the vineyard was estimated, using production factors, vineyards’ attributes, management strategies, and climate-related conditions as explanatory variables. An interesting contribution of this study is the identification of TVP functions for land, fertilizers, fungicides, other agrochemicals, labor, and the age of vines. Our results show that the training system has the most impact on TVP, where tendone-trained vineyards demonstrated 50% higher TVP than those vertically trained. Reserve quality production also has a positive effect on TVP, increasing it by 22% compared to vineyards producing varietal quality grapes. In contrast, the use of pressurized irrigation systems and mechanization in harvesting do not present a significant effect on TVP. The findings of this paper represent an advance in the understanding of the economic performance factors associated with wine grape growing and could serve to guide on-farm decisions and sectoral policies in pursuing the competitive development of wine grape growers

Spatial Variability of Production and Quality in Table Grapes ‘Flame Seedless’ Growing on a Flat Terrain and Slope Site

(1) Background: Precision agriculture has been used mostly to study spatial variability in vineyards for winemaking. Nevertheless, there is little available information on the impacts of its use on table grape vineyards under different slope conditions. (2) Methods: The aim was to study the spatial variability of production and berry quality in ‘Flame Seedless’ vines established on a flat (3% slope) and sloping (23% slope) terrain in the Chilean hyper-arid northern region. (3) Results: The results showed that in both vineyards, the measured variables presented a high spatial variability according to their coefficient of variation, being higher in slope than in the flat vineyard. The geostatistical analysis showed that 82% of the measured variables presented a strong spatial dependence in the slope vineyard, whereas 45% and 55% of the variables measured in the flat vineyard presented strong and moderate spatial dependence, respectively. Elevation was related to berry quality parameters in both vineyards, while trunk vine circumference was related to berry quality for the slope vineyard and to yield for the flat vineyard. (4) Conclusions: There is an important spatial variability in table grape vineyards mostly those cultivated on slope sites. Therefore, precision agriculture tools can be useful for zoning table grape vineyards, and thus improving both economic returns of viticulturists and sustainability

Sunscreen Based on Dicarboxylic Acid Salts Applications to Blueberries (<i>Vaccinium corymbosum</i> L.) Plants: Effects on Water Stress Tolerance and Productivity

Background: Recently, antitranspirant or radiation-reflective products have been studied in several crops to mitigate the negative effects of global warming in Mediterranean climates. Nevertheless, to our knowledge, there is a scarce availability of information studying their effects on blueberries and much less from applications of sunscreens elaborated based on a mixture of dicarboxylic acids. Methods: Controls and three treatments were performed in ‘Duke’ and ‘Star’ blueberries as follows: (i) control without water stress (T1 = 100% ETc); (ii) foliar application of sunscreen in plants without water stress (T2 = 100% ETc + sunscreen); (iii) water stress in plants without foliar application of sunscreen (T3 = 50% ETc); (iv) foliar application of the sunscreen in plants with water stress (T4 = 50% ETc + sunscreen). Stem water potential (Ψs), stomatal conductance (gs), yield, berry weight and berry total soluble solids were determined. (3) Results: As expected, the decrease in irrigation frequency in water stress treatments (T3 and T4) allowed for a decrease in the water applied at 25% compared to non-stressed plants (T1 and T2). This resulted in an increase in the Ψs on the days closest to harvest in both varieties, decreasing gs in blueberries plants subjected to water stress conditions. Sunscreen applications to Duke plants subjected to water stress (T4) induced higher total berry soluble solids than the treatments performed in non-stressed plants (T1 and T2). Sunscreen applications to Star plants subjected to water stress (T4) promoted similar gs levels and did not affect total soluble solids concerning irrigated plants (T1 and T2). (4) Conclusions: The results suggest that the response to water stress to sunscreen application based on dicarboxylic acid salts depended on the cultivar. Therefore, despite the novelty of this research, it is necessary to perform long-term studies to establish accurate conclusions

Leaf Morpho-Colorimetric Characterization of Different Grapevine Varieties through Changes on Plant Water Status

(1) Background: Currently, some ampelographic methods are developing in order to identify grapevine varieties. For this purpose, morpho-colorimetric parameters in leaves have been analyzed by digital imagen analysis, but some environmental conditions may affect their determinations. (2) Methods: A research study was conducted to characterize leaf morpho-colorimetric parameters in five grapevine varieties growing under different plant water status and to discriminate them under these conditions. Leaves were collected in vines, and twelve leaf morpho-colorimetric and fractal dimension variables were assessed. (3) Results: Merlot presented the highest values of perimeter and area to perimeter ratio in leaves and higher leaf area than Chardonnay in both plant water conditions. Most of the leaf morpho-colorimetric variables allowed discriminating the grapevine varieties under the contrasted hydric conditions. Under non-water stress, Carmenère was not related to any measured parameters. Merlot was positively related to most of the leaf morphometric parameters, whereas Chardonnay presented the opposite behavior. RGB color system variables allowed discriminating the grapevine varieties under water stress conditions, and Sauvignon Blanc was not related to any measured parameter. Chardonnay and Pinot Noir were positively related to green color and negatively related to most of the leaf morphometric parameters, whereas Merlot showed the opposite behavior. (4) Conclusions: Leaf morpho-colorimetric and fractal dimension parameters were affected by plant water stress and more variables should be incorporated into the new ampelographic methods in order to characterize leaf morpho-colorimetric parameters of the different grapevine varieties more clearly

Performance of a decision rule for integrated control of powdery mildew in grapevine in the central region of Chile

The dominant strategy followed by vine-growers in Chile to control powdery mildew (Erysiphe necator) involves schedule phytosanitary applications resulting between 9 to 18 fungicide sprays depending on the grape cultivar and the geographical area, mainly with sulphur applications. This large application of chemicals generates many environmental and human health risks To solve this, the present study aimed at evaluating the effectiveness of a Phytosanitary Decision Rule (PDR) proposed by French pathologists to rationalize fungicide applications against powdery mildew in grapevine. The PDR was evaluating in two irrigated vine fields, one of cultivar Cabernet sauvignon (CS, 1.56 ha) and another of Chardonnay (CH, 1.66 ha), in the Mediterranean climatic conditions of Talca Region, Chile. The experiment was carried out between 2009 and 2013. For the two experimental fields, two strategies to control powdery mildew were distributed in a randomized block design with four replicates: i) “Optimized traditional management” (OPT), which consisted in periodic applications (mainly sulphur), but with no more than nine treatments per season, ii) Application of a PDR based on field observations but with no more than four treatments per season. Untreated vines were left in each block to assess disease pressure at each studied season. Finally, a survey was conducted to know the practices of crop protection of traditional vine-growers (TVG) in the area, who carry out a “zero risk” strategy without limiting the number of phytosanitary applications. At veraison stage, clusters were observed to assess disease severity. The results show that powdery mildew control based on a PDR was as effective as schedule applications used by the OPT at experimental station for both vine fields. In the OPT and PDR treatments disease severity was lower than 5 %, which was considered as a threshold value for avoid in gloss of wine quality. For both cultivars disease severity was lower than that observed in untreated vines (close to 10% and 40 % for CS and CH, respectively). In the OPT treatment 7 to 9 applications per season independent of cultivar were made, whereas in the PDR treatment only 2-4 application were carried out. The differences are even greater when comparing the PDR with the TVG strategy in which, independent of the season and the cultivar, performed an average of 14 fungicide applications. Finally in the OPT and PDR treatments the cost per season was similar and fluctuated between US $322 and 415 per hectare independent of the cultivar. This value is 60$ 322 et 415 par hectare, valeur qui est 60% inférieure au coût de la stratégie “risque zéro” de viticulteurs

Performance of a decision rule for integrated control of powdery mildew in grapevine in the central region of Chile

The dominant strategy followed by vine-growers in Chile to control powdery mildew (Erysiphe necator) involves schedule phytosanitary applications resulting between 9 to 18 fungicide sprays depending on the grape cultivar and the geographical area, mainly with sulphur applications. This large application of chemicals generates many environmental and human health risks To solve this, the present study aimed at evaluating the effectiveness of a Phytosanitary Decision Rule (PDR) proposed by French pathologists to rationalize fungicide applications against powdery mildew in grapevine. The PDR was evaluating in two irrigated vine fields, one of cultivar Cabernet sauvignon (CS, 1.56 ha) and another of Chardonnay (CH, 1.66 ha), in the Mediterranean climatic conditions of Talca Region, Chile. The experiment was carried out between 2009 and 2013. For the two experimental fields, two strategies to control powdery mildew were distributed in a randomized block design with four replicates: i) “Optimized traditional management” (OPT), which consisted in periodic applications (mainly sulphur), but with no more than nine treatments per season, ii) Application of a PDR based on field observations but with no more than four treatments per season. Untreated vines were left in each block to assess disease pressure at each studied season. Finally, a survey was conducted to know the practices of crop protection of traditional vine-growers (TVG) in the area, who carry out a “zero risk” strategy without limiting the number of phytosanitary applications. At veraison stage, clusters were observed to assess disease severity. The results show that powdery mildew control based on a PDR was as effective as schedule applications used by the OPT at experimental station for both vine fields. In the OPT and PDR treatments disease severity was lower than 5 %, which was considered as a threshold value for avoid in gloss of wine quality. For both cultivars disease severity was lower than that observed in untreated vines (close to 10% and 40 % for CS and CH, respectively). In the OPT treatment 7 to 9 applications per season independent of cultivar were made, whereas in the PDR treatment only 2-4 application were carried out. The differences are even greater when comparing the PDR with the TVG strategy in which, independent of the season and the cultivar, performed an average of 14 fungicide applications. Finally in the OPT and PDR treatments the cost per season was similar and fluctuated between US $322 and 415 per hectare independent of the cultivar. This value is 60$ 322 et 415 par hectare, valeur qui est 60% inférieure au coût de la stratégie “risque zéro” de viticulteurs

Evaluation of a decision support strategy for the control of powdery mildew (Erysiphe necator [Schw.] Burr.) in grapevine in the central region of Chile

BACKGROUND: The primary strategy to control powdery mildew in Chileanvineyards involves periodic fungicide spraying, which may lead to many environmentaland human health risks. This study aimed to implement and evaluate the effectivenessand economic feasibility of a novel Decision Support Strategy (DSS) to limit thenumber of treatments against this pathogen. An experiment was conducted between the2010 and 2013 seasons in two irrigated vine fields, one containing a cultivar ofCabernet Sauvignon (CS) and another of Chardonnay (CH).RESULTS: The results showed that the DSS effectively controlled powdery mildew inCS and CH vine fields as evidenced by a disease severity lower than 3%, which waslower than that observed in untreated vines (approximately 10% and 40 % for CS andCH, respectively). The DS strategy required the application of only 2-3 fungicidetreatments per season in key vine phenological stages, and the cost fluctuated betweenUS $ 322 and 415 per hectare, which was 40 to 60 % cheaper than the traditionalstrategy employed by vine growers.CONCLUSION: The Decision Support Strategy evaluated in this trial allows a goodcontrol of powdery mildew for various types of epidemics with an early and lateinitiation