Table Grape Vineyards Research Articles

Does a native and introduced cover crop species differ in their ability to suppress weeds? A study in a table grape vineyard

This study compared the weed suppression ability of a native cover crop species phacelia (Phacelia tanacetifolia), an introduced cover crop species rye (Secale cereale L.), and a no cover crop (herbicide‑managed) system in a vineyard. Cover crops were sown in the interrow spaces of the grapevine rows. Percent weed cover after the cover crop termination was lower in the interrow of the phacelia than the no cover crop plots. During the cover crop growing season, phacelia suppressed weeds more than rye. However, the weed seedbank of the cover crop plots was greater than that of the no cover crop plots.

Experimental quantification of mating disruption for false codling moth, Thaumatotibia leucotreta (Lepidoptera: Tortricidae), in stone fruit and table grape cultivation

Mating disruption is the broadcasting of female pheromones within an agricultural system to interfere with, or decrease, the reproductive potential of the pest insect. Seen as a sustainable, nonchemical management method, it is used in citrus orchards against false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). Research to support its efficacy against FCM is limited, especially in stone fruit and table grapes. Previous efforts to quantify mating disruption against FCM have yielded inconsistent results, highlighting the necessity for additional investigation. In the present study, an experimental design that provides reliable results was evaluated. Following their release in a stone fruit orchard and a table grape vineyard, sterile males were recaptured with a trapping grid every 24 h, for five days. Trapping efficiency, trap interference and recaptures of wild and sterile moths were compared. Factors that improved the reliability of results included the use of mark-release-recapture experiments, using a nine-trap layout and a paired control, which ensured that only one variable was changed. Experimental blocks were then either treated with 400 or zero pheromone dispensers/ha. The current study reports the first experimental evidence that mating disruption is an effective control method against FCM in stone fruit and table grapes. Mating disruption was calculated at 86% in stone fruit and 93% in table grapes, with less than the field dose, indicating that mating disruption shows promise as a control technique against FCM, in both stone fruit and table grapes. The present study, therefore, sets a solid foundation for further research into the mechanistic understanding of how the pest is disrupted, as well as into calculating the dosage causing the highest level disruption with the smallest amount of pheromone.

Estimation of Intercepted Solar Radiation and Stem Water Potential in a Table Grape Vineyard Covered by Plastic Film Using Sentinel-2 Data: A Comparison of OLS-, MLR-, and ML-Based Methods.

In the framework of precision viticulture, satellite data have been demonstrated to significantly support many tasks. Specifically, they enable the rapid, large-scale estimation of some viticultural parameters like vine stem water potential (Ψstem) and intercepted solar radiation (ISR) that traditionally require time-consuming ground surveys. The practice of covering table grape vineyards with plastic films introduces an additional challenge for estimation, potentially affecting vine spectral responses and, consequently, the accuracy of estimations from satellites. This study aimed to address these challenges with a special focus on the exploitation of Sentinel-2 Level 2A and meteorological data to monitor a plastic-covered vineyard in Southern Italy. Estimates of Ψstem and ISR were obtained using different algorithms, namely, Ordinary Least Square (OLS), Multivariate Linear Regression (MLR), and machine learning (ML) techniques, which rely on Random Forest Regression, Support Vector Regression, and Partial Least Squares. The results proved that, despite the potential spectral interference from the plastic coverings, ISR and Ψstem can be locally estimated with a satisfying accuracy. In particular, (i) the OLS regression-based approach showed a good performance in providing accurate ISR estimates using the near-infrared spectral bands (RMSE < 8%), and (ii) the MLR and ML algorithms could estimate both the ISR and vine water status with a higher accuracy (RMSE < 7 for ISR and RMSE < 0.14 MPa for Ψstem). These results encourage the adoption of medium-high resolution multispectral satellite imagery for deriving satisfying estimates of key crop parameters even in anomalous situations like the ones where plastic films cover the monitored vineyard, thus marking a significant advancement in precision viticulture.

A native plant species cover crop positively impacted vineyard water dynamics, soil health, and vine vigor

Cover cropping is associated with multiple ecosystem and agronomic benefits. However, in irrigated orchards and vineyards of the dry, Western United States, cover crop adoption rates are low, often owing to concerns over their uptake of critical soil water. Regional concerns, such as this, must be addressed to identify sustainable agricultural practices that meet unique needs of diverse growing regions. A two-year study was conducted to determine the impacts of cover crops on soil water dynamics, soil health, and crop growth during the establishment of an Autumn King table grape vineyard in a semi-arid, Mediterranean climate, specifically the Central Valley of California. Phacelia (Phacelia tanacetifolia), a plant species native to the region, and an introduced species, rye (Secale cereale L. ‘Merced’), were planted as cool season cover crops in the interrow spaces of the grapevines and compared to a standard management practice of no cover crop interrow spaces. The cover crop treatments differentially impacted soil microbial biomass and soil aggregate stability, with the phacelia treatment enhancing both metrics from the first season. The phacelia treatment plots resulted in higher soil moisture beneath the vines in both years, while the rye treatment showed similar benefits only after two consecutive years of cover cropping. Vine vigor was also higher in the phacelia treatment, which was likely consequential of enhanced soil moisture in the rows. Compared to the rye, the phacelia had lower plant tissue carbon to nitrogen ratio and higher above ground plant biomass, which may underpin the soil health benefits associated with the phacelia, although variances in soil total carbon and nitrogen and ammonium and nitrate were not determined for any treatment. Altogether, we present information on cover crop plant traits that show quicker return on investment with regards to soil health improvements and water savings. Further, we demonstrate that cool season cover crops offered benefits for vineyard water productivity. In summary, for Mediterranean vineyards, cover crops can promote vineyard soil quality and be a component of sustainable water management.

Susceptibility of Grapevine Sucker and Green Shoot Wounds to Trunk Disease Pathogens

Grapevine trunk disease fungi infect vines through openings, primarily pruning wounds. The main objective of this study was to understand the role of sucker wounds and wounds made by the removal of green shoots from the stems of potted grapevines as potential points of infection for grapevine trunk disease pathogens. Six wine and four table grape vineyards of different ages were sampled in different production areas in the Western Cape grape region of South Africa. Isolations were made from 161 sucker wounds, and fungal pathogens were identified using morphology and DNA sequence analysis of the internal transcribed spacers (ITS1 and ITS2) and the 5.8S ribosomal RNA gene, the translation elongation factor 1alpha or the partial β-tubulin gene. The results show that 62% of the sucker wounds were infected by trunk disease pathogens, including Diaporthe ampelina, Diplodia seriata, Phaeomoniella chlamydospora, Phaeoacremonium minimum, Eutypella microtheca, Cryptovalsa ampelina and Neofusicoccum australe. Diaporthe ampelina was the most common, followed by D. seriata and P. chlamydospora, in both the wine and table grape sucker wounds. Under glasshouse conditions, wounds made by the removal of young green shoots on one-year-old potted grapevine plants were inoculated with spore suspensions of D. ampelina, E. lata, N. parvum, P. minimum and P. chlamydospora. After four months, all the inoculated pathogens could be re-isolated. This study shows that grapevine sucker and green shoot wounds are susceptible to different grapevine trunk disease pathogens and may therefore play a role in the epidemiology of trunk diseases.

Grapevine yellows in Jordan: Associated phytoplasmas, putative insect vectors and reservoir plants

AbstractField surveys were conducted in wine and table grape vineyards from June to October 2020 in 13 locations belonging to five governorates in North and South Jordan. Typical grapevine yellows symptoms, including leaf reddening/yellowing and rolling were observed on 10% to 55% of vines. Nested PCR‐based amplification of the 16S rRNA gene detected phytoplasmas in 22% and 15.7% of the analysed symptomatic wine and table grape cultivar plants, respectively. Amplicon nucleotide sequence analyses identified the detected phytoplasmas as “Candidatus Phytoplasma solani” (taxonomic subgroup 16SrXII‐A), “Ca. P. omanense” (16SrXXIX‐A and ‐B), “Ca. P. aurantifolia” (16SrII‐C) and “Ca. P. asteris” (16SrI‐R) in 72.4%, 17.2%, 6.9% and 3.4% of infected plants, respectively. Such phytoplasmas were found differentially distributed in wine and table grape cultivar vineyards surveyed. Further investigation identified “Ca. P. solani” in the putative insect vectors Orosius cellulosus (first report in Jordan), Euscelidius mundus, Laodelphax striatellus, and Circulifer sp., and in bindweed; “Ca. P. aurantifolia” in the insect O. cellulosus and in bindweed; “Ca. P. omanense” in the insect Psammotettix striatus; and “Ca. P. asteris” in the insects Arboridia adanae, Cicadulina bipunctata, Circulifer sp., L. striatellus, Hyalesthes obsoletus, and P. striatus. Based on this preliminary data, ecological cycles of such phytoplasmas are discussed. Results suggest that the diversity and ecology of grapevine yellows phytoplasmas in Jordan are more complex than previously known, leading to a potential risk of disease outbreaks.

Fungal species associated with grapevine trunk diseases in Washington wine grapes and California table grapes, with novelties in the genera Cadophora, Cytospora, and Sporocadus.

Grapevine trunk diseases cause serious economic losses to grape growers worldwide. The identification of the causal fungi is critical to implementing appropriate management strategies. Through a culture-based approach, we identified the fungal species composition associated with symptomatic grapevines from wine grapes in southeastern Washington and table grapes in the southern San Joaquin Valley of California, two regions with contrasting winter climates. Species were confirmed through molecular identification, sequencing two to six gene regions per isolate. Multilocus phylogenetic analyses were used to identify novel species. We identified 36 species from 112 isolates, with a combination of species that are new to science, are known causal fungi of grapevine trunk diseases, or are known causal fungi of diseases of other woody plants. The novel species Cadophora columbiana, Cytospora macropycnidia, Cytospora yakimana, and Sporocadus incarnatus are formally described and introduced, six species are newly reported from North America, and grape is reported as a new host for three species. Six species were shared between the two regions: Cytospora viticola, Diatrype stigma, Diplodia seriata, Kalmusia variispora, Phaeoacremonium minimum, and Phaeomoniella chlamydospora. Dominating the fungal community in Washington wine grape vineyards were species in the fungal families Diatrypaceae, Cytosporaceae and Sporocadaceae, whereas in California table grape vineyards, the dominant species were in the families Diatrypaceae, Togniniaceae, Phaeomoniellaceae and Hymenochaetaceae. Pathogenicity tests demonstrated that 10 isolates caused wood discoloration similar to symptomatic wood from which they were originally isolated. Growth rates at temperatures from 5 to 35°C of 10 isolates per region, suggest that adaptation to local climate might explain their distribution.

Do soil and climatic parameters affect yield and quality on table grapes?

Grape is considered as one of the world's most important crop. Climatic and soil parameters can significantly affect the yield and quality of grapes. The aim of this study was to analyse and assess this impact of soil and climatic conditions on table grape yield and quality. The experiments took place on a commercial table grape vineyard in Greece for three successive years (2015, 2016 and 2017). The climatic conditions were found to affect significantly the table grape yield and all the tested quality parameters apart from the berry density and titratable acidity. In addition, the climatic conditions affected the table grape yield and quality but in a different degree per phenological stage. The effect of soil conditions on table grape yield and quality parameters differed significantly per annum due to the climatic conditions variation in terms of temperature and precipitation. The conducted analysis highlighted that the information regarding the combined effect of weather and soil conditions on the spatiotemporal variability of the production of table grapes in terms of their quantity and quality is an essential component of the modern precision viticulture. Based on the contemporary principles of the precision viticulture, appropriate cultivation practices can be planned and implemented, reducing thus the impact of climate change on the vine production efficiency and quality.

Modelling the Impact of Water Stress during Post-Veraison on Berry Quality of Table Grapes

The aims of this work were modelling the effect of water stress intensity during post-veraison on table grape quality and yield, as well as predicting berry quality at harvest using a machine learning algorithm. The dataset was obtained by applying different irrigation regimes in two commercial table grape vineyards during seven growing seasons. From these data, it was possible to train and validate the predictive models over a wide range of values for the independent (water stress intensity and fruit load) and dependent (firmness and berry color) variables. The supervised learning algorithm Gaussian Process Regression allowed us to predict the variables with high accuracy. It was also determined that a reduction in irrigation of up to 40% during post-veraison, compared to vines without water limitations, and the accumulation of the water stress integral of up to 30 MPa per day, linearly increase the irrigation water use efficiency (IWUE) and promote higher berry color and firmness. The severe water scarcity and the increasing uncertainty about the irrigation water availability for the season that farmers are facing highlight the advantage of incorporating these validated techniques into agricultural decision making, as they allow for the planning of cultural practices and criteria to increase the IWUE and crop sustainability.

Responses of soil respiration and microbial community structure to fertilizer and irrigation regimes over 2 years in temperate vineyards in North China

Fertilizer and irrigation regimes can profoundly affect soil carbon (C) emissions, which influence soil organic carbon (SOC) storage. However, information regarding the effects of fertilizer and irrigation management on the components of soil respiration (Rs) and the underlying microbial community characteristics in vineyard ecosystems remains limited. Therefore, a 2-year field experiment was conducted in a wine-grape vineyard (WGV) and a table-grape vineyard (TGV). Each vineyard included two fertilizer and irrigation regimes: farmers' practice (FP) and recommended practice (RP). The trenching method was employed to separate Rs into heterotrophic respiration (Rh) and autotrophic respiration (Ra). Additionally, the SOC storage and soil microbial community structure at 0–20 cm soil depth were determined after the 2-year experiment. The results showed that the fertilizer and irrigation regimes caused no effect on Ra. Compared with the FP treatment in WGV and TGV, the RP treatment significantly (P < 0.05) decreased the average daily Rh by 15.13 % and 17.11 %, which contributed to the annual Rs values at the whole-vineyard scale decreased by 8.93 % and 11.78 %, respectively. Besides, compared with the initial value, the SOC storage under RP treatment were effectively increased by 6.39 % and 6.33 % in WGV and TGV, respectively. Low annual total Rh was partially ascribed to the significant (P < 0.05) decline in Proteobacteria and Bacteroidetes relative abundance, thus reducing the decomposition rate of SOC. Compared with WGV, the fertilizer and water input was higher in the TGV, which resulted in the annual total Rs and Rh values at the whole-vineyard scale was increased by 11.53 % and 15.74 %, respectively, while the annual total Ra was decreased by 18.83 % due to the lower grapevine density and more frequent summer pruning. Overall, RP treatment was found to be a suitable strategy for reducing soil C emissions and benefiting SOC storage in vineyards around North China.

Effects of water and nitrogen management on N2O emissions and NH3 volatilization from a vineyard in North China

Agricultural soils are a major source of anthropogenic N2O emissions and NH3 volatilization because of the large input of nitrogen (N) via fertilizers. Chinese vineyards commonly receive excessive water and N applications, but the response of gaseous losses to these management practices are not well documented. In this study, a field experiment was conducted to measure N2O emissions and NH3 volatilization from a typical table grape (Vitis vinifera L.) vineyard in North China. Three water and N regulation management strategies were applied and compared with the local farmer's traditional water and N management (TWN, traditional flooding irrigation and traditional N application rate, flood irrigation was carried out after the fertilizers furrowing-applied) as a control, mobile water and fertilization (MWF, 62% tradition N application rate and 60% traditional irrigation amount, flood irrigation was carried out after the dissolved fertilizers injected into rhizosphere (20 cm deep) with a liquid-jet gun), optimum water and N (OWN, 69% tradition N application rate and 70% traditional irrigation amount, the fertilization and irrigation method were the same as those in the TWN treatment) and optimum water and N combined with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) (OWN+DMPP, 1% DMPP was applied on the basis of the OWN treatment). The MWF, OWN and OWN+DMPP treatments significantly (P < 0.05) reduced the mean N2O fluxes with little effect on the NH3 volatilization rate. However, over the whole grape-growing season, the cumulative N2O total and yield-scaled N2O emissions in the three treatment groups were significantly reduced by 27.44–29.23% and 34.66–43.71%, respectively. In addition, the cumulative NH3 and yield-scaled NH3 volatilization were reduced by 4.13–6.61% and 21.81–26.15%, respectively. Notably, N2O emissions were significantly positively correlated with soil temperature, WFPS and NH4-N nitrogen contents, suggesting that these are the most important factors controlling N2O emissions in table grape plantations. Additionally, NH3 volatilization was closely related with soil temperature. Comprehensive evaluation showed that, based on the traditional water and N application rate, 38% N reduction combined with mobile water and fertilizer (MWF) effectively reduced the risk of N gaseous losses to the environment and saves irrigation water while maintaining grape yield.

Reduction of Evapotranspiration in Microenvironment Conditions of Table Grape Vineyards Protected by Different Types of Plastic Covers

Saving water is a major challenge to increase environmental sustainability, particularly in semi-arid regions where most table grapes are produced. Water use is driven by atmospheric demand, which combines effects of solar radiation (prominent factor), wind, air temperature and humidity. Covering table grapes with transparent plastics is spread in many regions. Covers lower incoming solar radiation and wind speed, changing air temperature and humidity. This study assessed the effects of two plastic covers on reference evapotranspiration (ET0) in comparison to the open field. For two years, two vineyards (cv. Victoria) trained to overhead trellis systems (tendone) were covered with two transparent polyethylene sheets: an agrotextile fabric (C), and a commercial film (S). The sheet spectrophotometric properties were analyzed and the radiometric coefficients calculated. Micrometeorological data were recorded in the covered vineyards and in a nearby uncovered one. ET0 was calculated for June and July using the simplified Penman–Monteith equation. The coefficient of transmissivity to total photosynthetic radiation, a proxy of net radiation, was 73% for cover C and 83% for cover S. On average, ET0 decreased by 35% under cover C and 31% under cover S. Hence, in addition to providing protection from external agents, covers represent a valid tool for saving water in table grape viticulture; nevertheless, their radiometric properties should be considered and optimized to better achieve this goal.

The effect of overhead netting on water utilization and soil water content of a table grape vineyard

The effect of overhead netting on water utilization and soil water content of a table grape vineyard

Determining a Midday Stem Water Potential Threshold for Irrigation of Table Grapes Water potential threshold

Sustainable table grape production depends on efficient water supply. Water potential is a useful indicator of water constraints in grapevines. In this regard, midday stem water potential (ΨS) is considered to be a better indicator of grapevine water status than leaf water potential (ΨL). The objective of the study was to determine a water potential threshold to set soil water refill lines for table grape irrigation. However, in previous studies carried out locally, only ΨL was measured. The relationship between ΨS and ΨL was determined for ten selected table grape cultivars. Since there were no differences between cultivars, a single equation could be used to convert midday ΨL measured in previous studies with table grapes to ΨS. Vegetative growth, berry mass and colour, as well as juice total soluble solids (TSS) data were pooled, and related to midday ΨS. This showed that -0.8 MPa seems to be a ΨS threshold for water constraints in the pre-harvest period that will allow sustainable growth and berry size for anisohydric table grape cultivars. The optimum ΨS for berry colour is between -0.8 MPa and -1.0 MPa. Consequently, a midday ΨS threshold of -0.8 MPa can be used to set refill points for irrigation where soil water content is measured on a regular basis in table grape vineyards.

Water Footprint of Table Grape Production Systems: A Review of South African and Global Studies

Being a water-scarce country, South Africa (SA) faces several water challenges, including drought and other effects of climate change. Therefore, there is a need to improve water-use efficiency (WUE) by accurately quantifying the water use and WUE of table grape vineyards. The objective of this review is to (i) provide an overview of water footprint (WF) studies conducted on table grape production systems in SA and globally; (ii) identify limitations in current WF assessments of table grape production systems; and (iii) establish a range of WF values for table grape production systems as an indicator of WUE and for use in decision-making regarding sustainable freshwater use. The review has demonstrated that only a limited number of detailed WF studies have been undertaken on table grapes in SA and globally. Region-specific lookup tables for quantifying blue, green and grey water use in table grape production systems are available for three table grape production regions of SA and could be used for future WF assessments. Most global studies conducted on grape WF and WUE were desktop studies and did not include actual field records from production units, nor did they distinguish between different grape types (table, raisin and wine grapes). WF values must be interpreted in context, specifically regarding the water used versus yield, quality and income, as well as the region, climatic conditions, soil characteristics, irrigation and cultivation practices. For future WF and WUE assessments, a more detailed breakdown of water use is recommended, both during the production process and postharvest.

Pre-Anthesis Cytokinin Applications Increase Table Grape Berry Firmness by Modulating Cell Wall Polysaccharides.

The use of plant growth regulators (PGRs) is widespread in commercial table grape vineyards. The synthetic cytokinin CPPU is a PGR that is extensively used to obtain higher quality grapes. However, the effect of CPPU on berry firmness is not clear. The current study investigated the effects of pre-anthesis applications (BBCH15 and BBCH55 stages) of CPPU on ‘Thompson Seedless’ berry firmness at harvest through a combination of cytological, morphological, and biochemical analyses. Ovaries in CPPU-treated plants presented morphological changes related to cell division and cell wall modification at the anthesis stage (BBCH65). Moreover, immunofluorescence analysis with monoclonal antibodies 2F4 and LM15 against pectin and xyloglucan demonstrated that CPPU treatment resulted in cell wall modifications at anthesis. These early changes have major repercussions regarding the hemicellulose and pectin cell wall composition of mature fruits, and are associated with increased calcium content and a higher berry firmness at harvest.

Climate change in a typical Apulian region for table grape production: spatialisation of bioclimatic indices, classification and Future Scenarios

The present research focused on the characterisation of climate evolution in a typical Apulian region for table grape production under the protected geographical indication, “Uva di Puglia I.G.P.”Two thirty-year time window period (TW) were analysed: 1961-1990 and 1991-2020. Georeferenced maps for both TWs were produced to delimit homogeneous zones and to evaluate the climate variability within the investigated area by means of the two bioclimatic indices, Heliothermal Index (HI) and Winkler Index (WI). Spatial analysis of HI and WI was performed using the regression-kriging (RK) interpolation method and the Digital Elevation Model/DEM (10 x 10 m) as a prediction attribute.An increase in both the minimum and maximum temperatures was observed, and locations above 300 m a.s.l. shifted from HI+1 “temperate warm” to HI+2 “warm” according to the Geoviticulture Multicriteria Climatic Classification System. WI values similarly increased between the periods 1961–1990 and 1991–2020, shifting all the sites grouped in the Elevation Classes defined as being below 300 m a.s.l. from Region IV to Region V of the Winkler Classification.According to HI and WI, presumed maturity was calculated as being reached 9 to 15 (HI) and 12 to 28 days (WI) earlier in 1991–2020 than in 1961–1990, taking into account the heat requirements of cv. Italia table grape (representative of Apulian table grape production), were set at 2200 for both indices on the basis of literature data.Moreover, three table grape vineyards, located in the three main producing provinces of Apulia (Bari, Taranto and Barletta-Andria-Trani (BAT)), were considered for future scenarios analysis on the basis of two different Representative Concentration Pathways (RCPs), 4.5 and 8.5, and classified according to the Geoviticulture Multicriteria Climatic Classification System (MCC). Future scenarios scored WI values that exceeded the threshold of 2700 in the BAT and TA provinces in the 2061–2090 time window period for RCP 8.5. In contrast, RCP 4.5 led to a mitigating effect, which was not noticeable until 2040, with a consequent reclassification of the investigated areas on the basis of HI and Cool Night Index (CI).These findings suggest that in order to prevent or overcome heat stress, it will be necessary to implement strategies, such as vineyard relocation to unexplored elevations or latitudes and/or the exploitation of new table grape varieties able to fulfill the optimal maturity parameters, even when the duration of the phenological phases is shorter.

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.

Reduced fitness cost and increased aggressiveness in fenhexamid-resistant Botrytis cinerea field isolates from Chile

Disease management programmes in Chilean table grape vineyards use the hydroxyanilide fenhexamid as a pivotal fungicide for Botrytis cinerea control. However, fenhexamid-resistant populations of this pathogen have progressively increased in vineyards under fungicide use. Botrytis cinerea isolates were collected in ‘Thompson Seedless’ vineyards under fenhexamid control programmes (&gt;two sprays per season) from three regions of Central Chile, during the 2013-2014, 2014-2015 and 2015-2016 growing seasons. Focusing on the 2015-2016 growing season when the greatest level of resistance was measured, only 8% of recovered isolates were sensitive to fenhexamid with 92% of isolates exceeding the sensitivity threshold for mycelium growth. All fenhexamid resistant isolates analyzed carried a mutation in the Erg27 gene, which encodes for 3-keto reductase (3-KR) enzyme. The largest proportion of isolates presented a single-point mutation, leading to a substitution of phenylalanine by serine or isoleucine in the 412 residue of 3-KR (erg27F412S, 27%; erg27F412I, 48%). Substitution by valine in this position was observed in a lower proportion of isolates (erg27F412V, 2%). In contrast to a previous report indicating high fitness cost in isolates carrying erg27F412S or erg27F412I, mycelium growth and sclerotia development under different restrictive temperatures were not affected compared to wildtype Erg27 F412 in Chilean mutant isolates. At 0°C, erg27F412S and erg27F412I generated larger lesions than erg27F412V and Erg27F412 isolates in wounded and unwounded berry assays. Another five mutations were detected in low-resistance Erg27 F412 isolates; one was a previously unreported mutation: erg27R330P. This study has demonstrated a significant loss of sensitivity to fenhexamid, limited fitness cost and high aggressiveness levels (erg27F412S and erg27 F412I) in field isolates carrying Erg27 mutations, giving dirctions for the design of Botrytis control programmes based on fenhexamid.

Soil and portable sensors for the management of the irrigation and berry ripening in cover cropped table grape vineyards

Soil and portable sensors for the management of the irrigation and berry ripening in cover cropped table grape vineyards