As we close the third fiscal year of the Canadian Agricultural Partnership, Grape & Wine Science Cluster each of the activities has provided a brief update on their research done so far. We thank Agriculture & Agri-Food Canada and British Columbia Wine and Grape Council, Grape Growers of Ontario, Ontario Grape and Wine Research Inc., Consiel des Vins Du Quebec, Nova Scotia Department of Agriculture and Grape Growers Association of Nova Scotia along with our Industry Partners for funding this research. We look forward to learning more over the next 2 years of the program. For more information, please contact us.
Activity 2 - Grape and Wine Viruses in British Columbia
The effect of Grapevine leafroll associated virus 3 (GLRaV-3) on vine health and fruit quality was assessed again in 2020 in one Cabernet Franc block and a Sauvignon Blanc block. This represents the 6th and 2nd year of data collection from these blocks. Results from the 2020 Cabernet Franc block are consistent with previous years and overall, reduction of soluble solids was observed from infected GLRaV-3 infected vines compared against healthy vines. No consistent differences were observed in the other plant health parameters evaluated. Contrary, no impacts were observed for the second year on GLRaV-3 infection at the Sauvignon Blanc block. Due to COVID-19 restrictions, wines could not be made in the 2020-2021 growing season. During the 2020-2021 growing season samples from several white cv blocks were collected and tested for GLRaV-3 in order to find a suitable block to conduct further work on the effects that GLRaV-3 has on white cvs. A Chardonnay and a Semillon block was found optimal to conduct this work, blocks were mapped and trials will start in the 2021-2022 growing season. Data analyses on the impacts of Grapevine red blotch virus (GRBV) on plant health and fruit and wine quality on a red Cabernet Franc cv. were finalized and publication completed (Bowen et al. 2020). Overall, GRBV showed a significant impact on plant health and fruit and wine quality, including a significant reduction of bud hardiness.
A pilot project evaluating rouging success for elimination of GRBV continued during the 2020-2021 growing season in 5 vineyard blocks. Preliminary results indicated low to minimum number of new infected vines in the blocks where GRBV vines were rouged in late winter of 2020. Monitoring will continue in 2021.
A seasonal dynamics study evaluating best timing and best type of sample to be collected for proper detection of GRBV was completed and manuscript has been submitted for publication. In summary, basal leaves during the entire growing season and middle leaves after veraison were the best samples to avoid GRBV false negatives. During dormancy, GRBV was detected from buds, dormant cane scrapings and roots but scrapings from dormant canes gave the best titer and results for GRBV detection in BC.
Evaluation of homopteran insects for their capability to transmit GRBV showed that two species of buffalo treehopper, Stictocephala basalis and S. bisonia, were vectors. A manuscript on the artificial diet system has just been accepted for publication in the Canadian Journal of Plant Pathology. Four species of treehoppers, all likely vectors of GRBV, have been identified from the Okanagan, with S. brevistylus being a new record for BC.
Mapping of GLRaV in new plantings continued in 2020. New infections were very low, most likely due to the small populations of vector scale and mealybug in the adjacent infected source blocks. To-date, soft scale and mealybug numbers have been assessed in 28 commercial vineyard blocks. During spring and summer 2020 we were unable to collect additional sites due to COVID restrictions. For the multi-year replicated spray trial at SuRDC with the neonicotinoid Clutch and the pyrethroid Pounce begun in 2019, scale numbers and parasitism rates were assessed 3 times over the growing season. Parasitism was generally higher in the Clutch treatment; 6 species were identified by molecular methods. Scale egg masses were also frequently host to silver fly larvae that consume the eggs.
Field spray trials could not be conducted in 2020 due to the COVID restrictions. Using cuttings with wintered soft scale rooted in cold storage on a warming bed we have been able to produce potted grapes with leaves infested with large numbers of nymphs that can be used in greenhouse spray trials. Unfortunately we could not proceed with greenhouse spray trials due to the COVID pandemic.
- Jose Urbez Torres, Tom Lowery, AAFC Summerland
Activity 3 - Grapevine Virus Diseases and Virus Vector Control
• The incidence of GLRaV-3 and GRBV was determined in 45 vineyards planted 2018-2021 using a medium-density sampling procedure. Sampled vineyards were in Niagara (40), Prince Edward County (1) and Lake Erie North Shore (4).
• The temporal and spatial distribution of grapevine leafroll-associated virus (GLRaV-3) and grapevine red blotch virus (GRBV) was determined in a red vinifera, a white vinifera and a white hybrid vineyard (3rd year).
• The effect of solo and coinfections of GLRaV-3 and GRBV on fruit yield and quality and cold hardiness were evaluated at the above blocks.
• The effect of applications of abscisic acid (ABA) for mitigation of impacts of GRBV on vinifera were evaluated in 4 blocks.
• GLRaV-3 vector populations were monitored from the dormant season in spring through harvest.
• Potential insect vectors of GRBV were sampled at 6 Niagara vineyards, and two potential GRBV vector species were tested for transmission of GRBV
Activity 4 - Evaluation of Viruses
Part I: Impact of key economic grapevine viruses on vine performance and fruit quality
Although a number of work plans were impacted by pandemic restrictions, we were able to make progress on objectives in the 2020 field season. Plans to establish baseline infection levels in an additional 10 varietal blocks in 2020 were not possible due to not having timely access to third party sites and labs for petiole processing. This also impacted plans to evaluate individual vines in commercial vineyards to assess virus impact on vine performance. Given the number of challenges (i.e. poor vine health, severe weather events) faced in the previous years of this study, a decision had been made to re-focus efforts towards potted plants to evaluate viruses of interest and establish a virus (positive and negative) field site at KRDC. No progress was made in setting up a potted plant trial and establishment of a field virus-block this past field season because of restrictions. As an alternative a trial was setup in the research vineyard located at the Kentville Research and Development Centre (KRDC) in late May 2020 to compare both, previously confirmed, Grapevine Leafroll associated Virus-3 (GLRaV-3) and Grapevine Red Blotch Virus (GRBV) infected plants. Plants infected with GLRaV-3 were compared to non-infected controls in ‘Vidal’ and ‘New York Muscat’ while the same was done for GRBV in ‘Marquette’. All vines-of-interest were inspected weekly to bi-weekly, photographed, and any observed symptoms recorded. The phenology and physiology (chlorophyll levels, carbon fixation rates, yield, fruit quality and dormant pruning weights) were assessed in both non-infected and infected vines across a number of time points. Grape samples from virus infected and non-infected vines were also collected to evaluate the effects of virus infection on grape chemical composition. Must from the grapes has been extracted and is being analyzed for sugar, acid and volatile composition using HPLC and GC-MS. Samples have also been frozen at -80C for subsequent phenolics assessment. At the end of September 2020, three 4-leaf samples (with petioles intact) were collected from each individual vine for subsequent work at KRDC and the Cool Climate Oenology and Viticulture Institute. Virus testing was conducted for Grapevine Leafroll associated Virus-1, GLRaV-3, GRBV, Grapevine Fan Leaf Virus, and Grapevine Pinot Gris Virus. The second set of petioles were immediately stored at -80C and processed over time to evaluate the impact of freezing samples directly before processing tissue into buffer. Weekly inspections for known vectors (mealybug and scale insects) were also conducted from the end of May through to mid-October 2020, in the KRDC research vineyard. A limited number of samples were also provided by local grape growers and identifications confirmed. Grape mealybug was not observed in the KRDC vineyard or submitted samples from growers and there were no reports of problems with this pest in 2020. Specimens and/or images of pest species of interest (not vectors) were routinely received by growers and/or from limited site visits and identified. Communications were ongoing with grape growers, extension specialists, researchers, and other industry stakeholders throughout the growing season through pest updates / newsletters, verbal and written report of activities for Activity 4 in 2020-2021 to the AAFC ASC-12 Canadian Grapevine Certification Network and presentation made to the GGANS Best Practices virtual workshop. Efforts to optimize molecular protocols for GPGV with collaborators at SuRDC and CCOVI continue. There remains a growing interest in incorporating wildflower plots as refuges for beneficial species, especially in organic production systems. The risk of increased incidence of grapevine viruses appears to be linked strongly to infected nursery material, since vector pressure remains very low in NS. Access to virus-free plant material remains a major priority.
Part II: Distribution and impact of emergent and invasive insect pest species in the context of viticultural expansion in Nova Scotia.
Despite a late start in establishing insect traps and initiating phylloxera sampling, efforts to determine the seasonal dynamics in soil emerging phylloxera counts and how this related to the presence of leaf galls, ambient air and soil temperatures, and vine phenology were done at the KRDC research vineyard. Non-invasive trapping, using plastic buckets, was used to capture phylloxera nymphs as they emerged from the soil and counts over time showed a large initial peak in numbers mid-summer and a smaller one somewhat later in the season during berry ripening. Based on findings previously reported in other wine-grape growing regions, the second peak would have been expected to occur after harvest. Since this is the first study of phylloxera in Nova Scotia, little is known about local population dynamics. Given that vines enter into senescence after harvest, where nutrients are transported to the roots of the plants instead of the leaves, it remains plausible that the ‘true’ second peak would have occurred later and was missed since sampling ended in September, prior to fruit harvest. General observations of leaf gall presence throughout the entire vineyard showed that phylloxera populations moved throughout the vineyard over the growing season and dispersal was likely facilitated by the direction of prevailing wind patterns. Leaf gall counts on vines was not found to be significantly correlated with the timing of highest soil emergence counts and the delay may be explained by the gap in time between when active stages emerge from the ground and the time it takes for galls to form on the leaves. Although gall presence remains the obvious measure for vineyard managers to use for decision-making as to whether to manage, it is likely an underestimate of the actual population that exists within the vineyard. Not surprisingly, temperature was found to have a significant effect on population dynamics. Soil temperatures between 21 and 25°C, at a depth of 30 cm, were correlated with the highest soil emergence levels and consistent with previously reported temperatures for optimal nymph survival (21-28°C). Monitoring of soil temperatures at various depths and relating to the timing of nymphs emerging from the soil may offer a more detailed profile of phylloxera dynamics sub-surface. Vine phenology was also found to have a strong correlation with phylloxera soil emergence. Periods of intense growth was associated with the highest insect counts suggesting that phylloxera emergence may be influenced by vine phenological stages where nutrients are in higher demand. Vine requirements for increased nutrients in new or developing tissue such as during rapid shoot growth or berry development could explain the correlation with nymphs emerging from the soil and moving up the vines to feed on new tissue that would act as a nutrient sink. Efforts going forward need to focus on replication of trials within commercial vineyards and extend the study duration to include the shoulder seasons and evaluation of potential management practices, especially in organic systems, that could include incorporating wildflower strips to encourage the diversity and abundance of natural enemies, to act as biological control agents. Due to restrictions, commercial vineyard monitoring efforts regarding other invasive and emerging insects focused on awareness and education. Newsletters ‘AAFC Pest Update’ were produced and disseminated to growers through the Grape Growers Association of Nova Scotia. The newsletter provided information of key pests, timing and suggested management. It is suspected that Grape Berry Moth, Paralobesia viteana, a potential new record for Nova Scotia, was found in a single vineyard in 2020, based on damage and images of the caterpillar stage. However, the integrity of the sample was compromised by the time of receipt and identification not possible. Monitoring efforts in 2021 will focus on the site suspected to have this pest and, if found, confirmation of species identification will be done through the AAFC National Identification Services.
- Debra Moreau, AAFC Summerland
Activity 5 - Cold Hardiness in Eastern Canada
Growing grapes in cold climates has several challenges to overcome. Cold injury to grapevines is an important problem, especially at the northern limits of culture where extensive damage to bud and cane tissues can result in severe economic losses. The main objective of this project is to improve knowledge of grapevine cold hardiness for hardy and semi-hardy hybrid and Vitis vinifera cultivars as well as to provide methods to reduce cold injury under climatic conditions of eastern Canada in order to support the development of the wine industry. To help understand cold resistance in grapevines, methods and models for evaluating bud resistance have been developed and utilized for several years. Following previous works, CRAM has set up a network of eleven vineyards across Quebec to monitor bud cold tolerance by means of Differential Thermal Analysis (DTA) during the winter and spring. The Low Temperature Exotherm (LTE) for each studied varietal can be derived in from DTA in order to demonstrate bud cold tolerance. The grape varieties that are followed from November to May are rustic hybrids, Frontenac, Marquette, St-Pepin, Frontenac blanc and Petite Perle. Then, from April on, V. vinifera (Chardonnay, Vidal and Pinot noir) are added. The first year of LTE monitoring in Quebec demonstrated that there was great variability in LTE values between vineyards and grape varieties. In addition, rustic hybrids do not seem to follow a standard curve of acclimation / maximum hardiness / deacclimation that is usually observed for V. vinifera. The LTEs are more variable during the winter and closely follow local outside temperature variations. Most notably, maximum hardiness was only attained at the end of February.
Winter protection methods have been developed to use concomitantly with tender and semi-hardy wine grapes that are less resistant to the cold in the northern regions. The use of geotextiles to protect semi-rustic and non-rustic vines is increasingly used in Quebec though without specific knowledge for optimal installation and outcome. The project evaluates three types of geotextiles (Hibertex 2.2 mm, Hibertex 3mm and Texel Arbo Pro) and four moments of installation/withdrawal (early installation/early withdrawal, early/late, late/early and late/late). Three grape varieties were followed: Vidal, Chardonnay and Pinot noir. The trials are carried out in seven vineyards across Quebec. A first site was installed in the fall of 2018 and the data was collected during the 2019 season. We can note that protecting the vines with geotextile maintains significantly higher temperatures under the geotextile, especially in presence of very cold weather. The later removal of the geotextile favoured the development of the vines in the spring, but very little effect was noted on the various parameters at harvest, except for a higher number of clusters for an early installation/early removal of the geotextiles comparatively to a late installation/late removal.
Several management practices can modulate the resistance to cold or vine acclimation, such as leaf removal, fertilization, pruning, training systems and rootstocks. Rootstocks can directly affect the biochemistry of grafts and tolerance to freezing or can affect cold tolerance indirectly by acting on the vigour of the vine and shade from the canopy. The effects of grafting for rustic grape varieties on various parameters have been monitored for several years. Thirty combinations including six grape varieties (Frontenac, Frontenac blanc, Frontenac gris, Marquette, Adalmiina, Baltica) and five root systems (pied franc, 3309, Riparia Gloire, 101-14, SO4) were studied. Grafting has little effect on bud survival rate during the winter, only a few non-constant differences are noted. Furthermore, after 5 years, vine development is also unaffected by grafting. Finally, grafting has variable effects on the parameters at harvest and some trends stand out. The most marked effect of grafting is in the wines produced. There is a general improvement in the appreciation of wines when the grapes come from grafted plants compared to grapes from own-rooted plants. Better understanding of physiology can lead to the development of new technology and adaptations to better protect grapevines against extreme winter temperatures. Important information will also be generated that could be used for more efficient management of frost protection systems, such as wind machines against spring frost.
La culture du raisin dans les climats froids doit relever plusieurs défis. Les dommages causés à la vigne par le froid constituent un problème important, en particulier aux limites septentrionales de la culture, où des dommages importants aux tissus du bourgeon et des tiges peuvent entraîner de graves pertes économiques. L’objectif principal de ce projet est d’améliorer les connaissances sur la résistance au froid des cépages hybrides (rustiques et semi-rustiques) et Vitis vinifera, ainsi que de proposer des méthodes permettant de réduire les dommages dus au froid dans les conditions de l’est du Canada, afin de soutenir le développement de l’industrie vinicole. Pour aider à comprendre la résistance au froid, des méthodes et des modèles d'évaluation de la résistance des bourgeons ont été développés. Le CRAM a mis en place un réseau de onze vignobles à travers le Québec afin de suivre la résistance des bourgeons au froid (LTE) durant la période hivernale et au printemps. Les cépages qui sont suivis de novembre à mai sont des hybrides rustiques, soit Frontenac, Marquette, St-Pepin, Frontenac blanc et Petite Perle, puis à partir du mois d’avril des non-rustiques sont évalués, soit Chardonnay, Vidal et Pinot noir. La première année de suivi des LTE au Québec a démontré qu’il y avait une grande variabilité des valeurs LTE entre les vignobles et les cépages. De plus, il a été observé que les hybrides rustiques ne semblent pas suivre une courbe standard du processus d’acclimatation/LTE optimale/désacclimatation que l’on peut observer pour les V. vinifera, les LTE sont beaucoup plus variables durant l’hiver et suivent les variations de la température extérieure.
Des méthodes de protection hivernale ont été mises au point pour utiliser des cépages moins résistants au froid (tendres, semi-rustiques) dans les régions nordiques. L’utilisation des toiles géotextiles pour protéger les vignes semi-rustiques et non-rustiques sont de plus en plus utilisées au Québec sans que l’on ait des connaissances spécifiques pour leur installation. Le projet évalue trois types de toiles (Hibertex 2.2 mm, Hibertex 3mm et Texel Arbo Pro) et quatre moments d’installation/retrait (installation tôt/ retrait tôt, tôt/tard, tard/tôt et tard/tard). Trois cépages sont utilisés : Vidal, Chardonnay et Pinot noir. Les essais sont réalisés dans sept vignobles à travers le Québec. Un premier site a été installé à l’automne 2018 et les données ont été collectées durant la saison 2019. On peut noter que la protection des vignes avec les toiles géotextiles permet d’augmenter la température sous les toiles de façon significative et ce surtout en présence de grands froids. Le retrait des toiles plus tardivement a favorisé le développement de la vigne au printemps, mais très peu d’effet a été noté sur les divers paramètres à la récolte, sauf un nombre de grappes plus élevé pour une installation et un retrait hâtif des toiles comparativement à une installation et un retrait tardif des toiles.
Plusieurs pratiques de gestion peuvent moduler la résistance au froid ou l'acclimatation de la vigne, telles que l'effeuillage, la fertilisation de la vigne, la taille, les systèmes de formation et les porte-greffes. Les porte-greffes peuvent influer directement la biochimie des greffons et la tolérance à la congélation ou peuvent affecter la tolérance au froid indirectement en agissant sur la vigueur de la vigne et l'ombrage du couvert. Les effets du greffage pour les cépages rustiques sur divers paramètres sont suivis depuis plusieurs années. Trente combinaisons incluant six cépages (Frontenac, Frontenac blanc, Frontenac gris, Marquette, Adalmiina, Baltica) et cinq systèmes racinaires (pied franc, 3309, Riparia Gloire, 101-14, SO4) sont étudiés. Le greffage a peu d’effet sur le taux de survie des bourgeons suite à l’hiver, seulement quelques différences non constantes sont notées. Le greffage n’affecte pas le développement de la vigne qui est établie depuis 5 ans. Enfin, le greffage a des effets variables sur les paramètres à la récolte et quelques tendances se démarquent. L’effet le plus marqué du greffage est au niveau des vins produits, on note une amélioration générale de l’appréciation des vins lorsque le raisin provient de plants greffés comparativement à du raisin de plants franc de pied. Une meilleure compréhension de la physiologie peut conduire au développement de nouvelles technologies et à des adaptations visant à mieux protéger les vignes contre les températures extrêmes en hiver. Des informations importantes seront générées dans le cadre du projet et elles pourraient être utilisées pour une gestion plus efficace des systèmes de protection contre le gel, tels que les éoliennes contre le gel printanier.
- Gaetan Bourgeois and Caroline Provost, AAFC Kentville and Centre de Recherche agroalimentaire de Mirabel
Activity 6 - Grape & Wine Grapevine Hardiness
In Activity 6 “Factors Affecting Grapevine Winter Hardiness” there are 6 objectives all with the common purpose of increasing our understanding of grapevine winter hardiness. This includes investigating the vulnerability of grapevine buds, canes, cordons, trunk and roots to sub-zero temperatures and to elucidating factors in vineyard management and site conditions that both positively and/or negatively affect grapevine hardiness. Despite SuRDC closure and major restrictions on research activities due to Covid19 the overall goals of this activity were largely met as planned for this year.
Results and preliminary analysis from the 2020 - 2021 are presented in this report: of note, is the writing of six additional predictive bud hardiness models for the Okanagan Valley, BC. Bud hardiness models have now been written for Chardonnay, Merlot, Shiraz, Riesling, Cabernet sauvignon, Pinot noir, Pinot gris and Sauvignon blanc. Also, using the framework of the Okanagan hardiness models a similarly accurate bud hardiness model was written for Chardonnay grown near Vineland Ontario, and collaboration with Jim Willwerth at Brock University has begun in earnest.
This activity is largely on track to complete most annual milestones for 2020 – 2021 (note: due to the pandemic and the closure of SuRDC beginning on March 17, 2020 the collection of end of winter season 2019-2020 data for some experiments was missed, and all summer 2020 field experiments were postponed until 2021.) Due to restrictions on research activities not all of the 2020-21 budget was spent. Research and knowledge transfer to industry members regarding grapevine winter hardiness continues.
- Carl Bogdanoff, AAFC Summerland
Activity 7 - Grapevine evaluation and cold hardiness program
Vote 1: AAFC Kentville
Specific objectives of the proposed research include: (3) Coordinate annual grapevine bud hardiness survey activities between the Kentville Research and Development Centre (KRDC) (Kentville, Nova Scotia), Summerland Research and Development Centre (SuRDC) (Summerland, British Columbia) and the Cool Climate Oenology and Viticulture Institute (CCOVI) (St. Catharines, Ontario); (4) Investigate causative factors of winter injury not captured by tracking grapevine bud LTEs (i.e. chronic as opposed to acute winter injury); (5) Evaluation of Chardonnay clones for cold hardiness and performance under Nova Scotia conditions to support the Canadian Grapevine Certification Network. For objective 3, the pandemic response meant the 2019-2020 bud hardiness season was cut short by roughly 5 or 6 weeks and there was a delay in starting the survey in 2020-2021 by approximately 4 or 5 weeks. Since its initiation in early December, the survey has been conducted and bud hardiness reports produced on a biweekly basis. Reports are distributed via the Grape Growers’ Association of Nova Scotia (GGANS) distribution list and posted on the Clean Grape Certification Network’s (CGCN) website as well as the Perennia (provincial agriculture development agency) website. For objective 4, bud viability assessments, initiated during the 2019-2020 dormant season, are again being performed this season every 4 weeks. Work continues on the nature of the low temperature exotherms (LTEs) over the course of the season and the water status of the buds. Work also continues collecting samples for chemistry analyses over the course of the dormant season. The protocol for a carbohydrate and starch analysis of the vines has now been worked out; in the coming months the plan is to start processing stored samples from the past 3 years in earnest. It is hoped that a great contrast in the nature of the seasons (2018 was the year of the June frost, 2019 was one of the cooler seasons on record while 2020 was one of the warmest) over the past three years will make for interesting results. Objective 5 was delayed in 2020 as a result of the pandemic. Orders for 5 separate ‘Chardonnay’ clones were cancelled approximately 10 days before the vines were scheduled to arrive. Only three ‘Chardonnay’ clones were found to be available from virus-free sources in 2021; unwilling to delay action on this objective further, the decision was made to reduce the scope of this objective and proceed with only 3 clones as we plan to plant in June of 2021.
Vote 10: CCOVI, Brock University
Objectives within this activity include: 1) Gain in‐depth understanding of scion‐rootstock combinations to optimize vine performance with respect to production, cold tolerance and fruit/wine quality using certified nursery material; and 2) Elucidate relationships between different grapevine genotypes, cold tolerance, dormancy and associated cold hardiness‐related metabolites in their biochemical and physiological responses as well as improving hardiness through Abscisic Acid (ABA) analogs. The effects of clone x rootstocks on vine performance, cold hardiness and fruit composition have now been evaluated for 3 seasons (2018-21) for Cabernet franc. We have found some specific impacts of clone x rootstock with Cabernet franc but the differences are not as evident as previous work with Sauvignon blanc and Riesling. Furthermore, dehydrin proteins were measured for 2 seasons and while these individual proteins varied over dormancy there were no clear indications that dehydrins were associated with greater hardiness. Climate conditions over dormancy did impact clone x rootstock hardiness as well as dehydrins. Dehydrin levels did increase following cold events and after hardiness levels increased. We are continuing to analyze fruit composition differences but clone x rootstocks do impact vine size, yields, crop loads and some primary fruit chemistry.
For objective 2, we continue to find that ABA analogs can improve and maintain dormancy in multiple cultivars including cold tender V. vinifera as well as hybrid cultivars over a 3 year period. We are now elucidating the effects of the ABA analog treatments at the molecular level, through some additional supporting funding from OGWRI, by targeting key genes to follow and analyze during the key periods of cold acclimation, deacclimation and reacclimation phases. The targeted genes will be based on our current understanding of cold tolerance in grapevines and key cold-hardiness related metabolites. Preliminary data suggests that there may be unique responses and pathways to grape but this work needs to be continued in 2021.
The Covid-19 pandemic delayed some fruit composition analyses since we had restricted laboratory access during some “lockdown” periods but also had some physical distancing restrictions that limited number of people within the labs. However, we are happy to report that no critical data was lost due to the pandemic as field work continued as usual and all samples/measurements were taken and field experiments could be initiated such as in the case of the ABA analog experiments.
- Harrison Wright and Jim Willwerth, AAFC Kentville and CCOVI at Brock University
Activity 8 - Canopy Management to reduce disease pressure
Vote 1: AAFC CRDH
Practices of fruit zone management were evaluated for their effect on downy mildew in plots planted with Vidal blanc and on powdery mildew and Botrytis bunch rot in plots planted with Seyval blanc. At both sites and for both grape varieties, the following five practices of leafing around the cluster zone were: on 1) one side of the row at nouaison; 2) two sides of the row at nouaison ; 3) one side of the row at veraison; 4) two sides of the row at veraison; 5) no leafing (control). Canopy density was assessed by measuring cluster exposure layer (number of shading layers between clusters and the nearest canopy boundary). Microclimate (temperature, relative humidity, leaf wetness, solar radiation) was monitored within the fruit zone and fungicide penetration was measured with hydrosensitive paper. Downy mildew and powdery mildew, were assessed weekly on leaves and at harvest on clusters, while Botrytis bunch rot was assessed only at harvest on clusters. Disease pressure (pathogen’s airborne inoculum) was monitored using rotating-arms samplers The number of spores of P. viticola, E. necator and B. cinerea per sampling period was determined using a previously developed qPCR assay. Yield was assessed as the number of clusters, cluster weight and brix. The influence of leafing treatments on the different variables were analysed using ANOVA. In addition, according to the literature and the 2019 results, it is unlikely that leafing around the cluster zone by itself may not be cost-effective in terms of disease management. On the other hand, if several canopy management practices are used together, the addition of the effect of each practice could make it possible to reduce the use of fungicides and allow the use of products that are less effective but less harmful to the environment. To investigate this hypothesis, at both sites variables related to shoot vigor, vine architecture, cluster and yield components, microclimate, and disease incidence were collected on 50 randomly selected vines. Principal component analysis (PCA) will be used to extract maximum variance from the data with only a few components and to identify relationships among variables.
For downy mildew, disease onset was delayed in plots where leafing was done at nouaison, and downy mildew severity on bunches at harvest was significantly lower than the plots where no leafing was done only inplots where leafing was done at nouaison on both sides of rows. For powdery mildew, significantly lower disease was observed in plots where leafing was done on both sides of rows at nouaison and at veraison. At harvest, powdery mildew severity was significantly lower in plots where leafing was done at nouaison. For botrytis bunch rot, , percent cluster area diseased were lower in plots where leafing was done at nouaison on two sides of rows and when done at veraison on one or two sides of row. Overall, the season 2020 was characterized by several periods without rain, hence number and duration of wet periods (infection by P. viticola and B. cinerea) were low, especially in May, June and July. Consequently there were only small differences between canopy wetness among the leafing treatments. However, it was different in August and in September where significantly shorter wetness period were observed in plots where leafing was done at nouaison on both sides and at veraison on one or two sides.
The most significant difference between the leafing treatment was the penetration of fungicides into the grape canopy. They was a significant difference in spray deposition (cm2) in plots where no leafing was done and where leafing was done at nouaison and at veraison. For both leafing timing spray deposition (cm2) was significantly higher when leafing was done on both sides of rows compare to only on one side. However, the difference was high soon after leafing and diminished over time. Overall, results obtained up to now suggest that under northern condition, canopy management can play a major role in disease management.
Vote 10: CRAM
There is a general agreement among scientists and grape specialists that proper canopy and fruit zone management are essential practices to obtain qualitative grapes. Canopy management (CM) involves pruning, shoot thinning, sucker removal, shoot positioning, leaf and lateral removal, hedging and any other practice that manipulates shoots and leaves. Fruit zone management (FZM) involves de-leafing around the cluster. The ultimate objective of both CM and FZM is to improve grape aroma, flavour and pigment profiles, favour earlier maturity and reduce diseases. Practices of fruit zone management were evaluated for their effect on disease management during summer 2019. The practices were leafing around the cluster zone on 1) one side of the row at nouaison; 2) two sides of the row at nouaison ; 3) one side of the row at veraison; 4) two sides of the row at veraison; 5) no leafing (control). Microclimate (Temperature and relative humidity) was monitored within the fruit zone and fungicide penetration was measured with hydrosensitive paper. Downy mildew, powdery mildew, and botrytis bunch rot were assessed weekly and at harvest on clusters. Disease pressure (pathogen populations) was monitored using rotating-arms samples. The number of spores P. viticola, E. necator and B. cinerea per sampling period was determined using a previously developed qPCR assay (Carisse et al., 2014). Yield was assessed as the number of clusters, cluster weight and brix. Regardless of the treatment, the effect of fruit zone management practices was small but significant. For both timing of cluster zone leafing, nouaison and veraison, lower disease severity was observed when leaves were removed on both sides of rows. Overall, lowers disease severity was observed when leaves were removed at veraison as compare with nouaison. However, there was no significant difference in airborne inoculum. The difference in disease severity may be explained by lower humidity and better fungicide penetration in the canopy in sub-plots where leaves around the clusters were removed on both sides of rows at veraison. The removal of leaves from the fruiting area promotes the penetration of fungicides during a localized treatment but also of general coverage.
A portrait of the Quebec grape industry was made to evaluate the current canopy management practices including timing, level of exposure and the grower’s expected benefit. A questionnaire (survey) was developed to evaluate grape grower’s practices related to canopy and fruit zone management, equipment used, time required/ha, timing, impact on their disease management program, and their expected outcomes. Surveys was be conducted as a web version or in person with a follow up site on selected vineyards, based on CM and FZM practices used by the growers. Particular attention was paid to obtain vineyards in several regions (Québec), with different grape varieties and diversified cultural practices. Overall 62 grape growers from 11 growing regions of Quebec answered which allow us to make a very good portrait of the industry. Based on the survey, 55%, 80%, 15%, 74%, 69%, and 31% are doing shoot thinning, shoot positioning, fruit thinning (vendange en vert), hedging, lateral removal, and leafing around the cluster, respectively. These canopy management practices are done manually in 91%, 98%, 97%, 44%, 46%, 84% for shoot thinning, shoot positioning, vendange en vert, hedging, lateral removal, and leafing around the cluster, respectively.
Les scientifiques et les spécialistes de la vigne sont généralement d'accord sur le fait qu'une bonne gestion de la canopée et de la zone fruitière sont des pratiques essentielles pour obtenir des raisins de qualité. La gestion de la canopée (CM) implique l'éclaircissage fructifère, l’épamprage, le positionnement des tiges, le rognage et l’écimage et toute autre pratique qui manipule les pousses et les feuilles. La gestion de la zone fruitière (FZM) implique l’effeuillage autour de la grappe. L'objectif ultime du CM et du FZM est d'améliorer les profils d'arôme, de saveur et de pigment du raisin, de favoriser une maturité plus précoce et de réduire les maladies. Les pratiques de gestion de la zone fruitière ont été évaluées pour leur effet sur la gestion des maladies durant la saison 2019. Les essais comprenaient l’effeuillage autour de la zone de grappe sur 1) un côté du rang à la nouaison; 2) deux côtés du rang à la nouaison; 3) un côté du rang à la véraison; 4) deux côtés du rang à la véraison; 5) aucun feuillage (témoin). Le microclimat (température et humidité relative) a été collecté dans la zone fruitière et la pénétration du fongicide a été mesurée avec du papier hydrosensible. Le mildiou, l'oïdium et la pourriture liée à Botrytis ont été évalués chaque semaine et à la récolte sur les grappes. La pression des maladies (populations d'agents pathogènes) a été suivie en utilisant des capteurs de spores. Le nombre de spores de P. viticola, E. necator et B. cinerea par période d'échantillonnage a été déterminé en utilisant un test qPCR développé précédemment (Carisse et al., 2014). Le rendement a été évalué comme le nombre de grappes, le poids des grappes et le brix. Quel que soit le traitement, l'effet des pratiques de gestion de la zone fruitière était faible mais significatif. Pour les deux moments d’effeuillage, à la nouaison ou à la véraison, la gravité des maladies était moindre lorsque les feuilles ont été enlevées des deux côtés du rang. Dans l'ensemble, une gravité plus faible de la maladie a été observée lorsque les feuilles ont été enlevées à la véraison par rapport à la nouaison. Cependant, il n'y avait pas de différence significative dans l'inoculum en suspension dans l'air. La différence de l’incidence des maladies peut s'expliquer par une humidité plus faible et une meilleure pénétration des fongicides dans la canopée dans les sous-parcelles où les feuilles autour des grappes ont été enlevées des deux côtés du rang à la véraison. L'élimination des feuilles de la zone de fructification favorise la pénétration des fongicides lors d'un traitement localisé mais lors d’un traitement avec une couverture générale.
Un portrait de l’industrie du raisin au Québec a été dressé pour évaluer les pratiques actuelles de gestion de la canopée, y compris le moment, le niveau d’exposition et les avantages escomptés du producteur. Un questionnaire (enquête) a été élaboré pour évaluer les pratiques des viticulteurs en matière de gestion de la canopée et de la zone fruitière, l'équipement utilisé, le temps requis / ha, le calendrier, l'impact sur leur programme de gestion des maladies et leurs résultats escomptés. Les enquêtes ont été menées en version Web ou en personne avec un suivi sur des vignobles sélectionnés, sur la base des pratiques CM et FZM utilisées par les producteurs. Une attention particulière a été portée à l'obtention de vignobles dans plusieurs régions (Québec), avec des cépages différents et des pratiques culturales diversifiées. Au total, 62 viticulteurs de 11 régions productrices du Québec ont répondu, ce qui nous permet de dresser un très bon portrait de l'industrie. Sur la base de l'enquête, 55%, 80%, 15%, 74%, 69% et 31% effectuent respectivement l'épamprage, le positionnement des tiges, l’éclaircissage fructifère (vendange en vert), l’écimage, le rognage et l’effeuillage. Ces pratiques de gestion de la canopée sont effectuées manuellement dans 91%, 98%, 97%, 44%, 46%, 84% pour l'épamprage, le positionnement des tiges, l’éclaircissage fructifère (vendange en vert), l’écimage, le rognage et l’effeuillage, respectivement.
- Odile Carisse and Caroline Provost, AAFC CRDH and Centre de Recherche agroalimentaire de Mirabel
Activity 9 - Optimization of grape production in Eastern Canada
Research summary to come.
- John DeLong and Karine Pedneault, AAFC Kentville and University Sainte-Anne
Activity 10 - Water and Nutrient management strategies for grapevines and health promoting natural products
British Columbia is home to 929 vineyards, covering 4,130 ha, from which 3,488 hectares are located in the Okanagan Valley and the nearby Similkameen Valley. BC wine industry is constantly looking for alternative solutions to enhance their productivity and environmental sustainability. A five year study is funded with the overall goal of find greener and more sustainable viticulture practices that supports the resilience of Canadian vineyards. Application compost+ biochar with or without cove crops in alleyways significantly affected petiole N, cover crops dry biomass, cover crops N and C contribution to soil and pruning weights. Cover crops reduced soil mineral N and consequently reduced petiole N. Compost + biochar treatments stimulated the cover crops establishment and growth particularly early in each growing season. Pruning weights were greater in control and compost+ biochar treatments likely due to cover crop completion, however this competition did not result in any negative impact on the yield or yield quality. In a newly established Riesling block (3rd year) soil water retention system (SWRT), Irrigation: 100 and 50% ET, and ± compost-biochar did not affect the vine and soil measurements. Seaweed extract treatments did not affect any of the measured vine or soil parameters in BC or NS. Cold bud hardiness data were collected but have not been analyzed yet.
- Mehdi Sharifi and Francisco Diez, AAFC Summerland and Perennia Agriculture and Food Inc.
Activity 11 - Grape & Wine Nitrogen Management
The production of high quality grapes and wine requires nitrogen (N). N directly impacts quality by influencing vine vigour, fruit set and maturation, crop load and pressure from diseases and insects. Throughout fermentation yeasts require yeast assimilable nitrogen (YAN) for growth and they transform nitrogenous compounds into flavours and aromas which influence wine quality. We propose to examine how different soil and foliar N applications influence the ratios of YAN components (ammonium and 20 alpha amino acids) in grapes and how they impact fruit and wine quality. Fermentation studies will investigate how individual components of YAN influence wine quality and what the nutritional requirements of yeast are in light of recent findings on the importance of non N nutrients and vitamins and investigate the YAN requirements under high sugar conditions such as those found in icewines. We will develop spatial precision approaches for monitoring N in vineyards through drone-based imaging. We will use nitrogen application to virus infected vines to stimulate photosynthetic capacity and investigate its effectiveness for alleviating symptoms including retarded maturation and chlorophyll loss.
During the 2020-21 season, challenges due to COVID-19 and the limited amount of work that could be completed resulted in a significant change to the work plan for this Activity. Three of the six objectives were deferred to the following year. The remaining three objectives were partially completed. The CRADA was amended to reflect these changes. Overall, two field trials were conducted to evaluate the effect of foliar and ground N application on fruit and wine quality. A small portion of work was done to capture aerial images of the N trials for precision management modeling. Wine was made from the field trials and chemical analysis of the fruit and wine is ongoing. We are optimistic the deferred work will be completed during the remainder of the project.
- Kevin Usher, AAFC Summerland
Activity 12 - TanninAlert: improving red wine quality and consumer acceptance
Research summary to come.
- Debra Inglis, CCOVI at Brock University
Activity 13 - Improving wine quality through mixed and sequential fermentation with indigenous yeasts
Winemaking is a burgeoning industry in Nova Scotia, with many new opportunities to create regionally distinctive products. While commercial yeasts are usually added to grape juice to induce wine fermentation, many native yeasts reside naturally on grape skins and can noticeably influence wine flavour (the “microbial terroir”). There is therefore recent interest in natural, or spontaneous, fermentations that forgo the addition of commercial yeast and rely on native yeasts to produce wines that are more representative of the local region. Although a lack of control over the end product makes natural fermentations somewhat risky, this can be reduced by using both native and commercial yeasts simultaneously (mixed fermentation), or by allowing the native yeasts to ferment initially, followed by commercial yeast to ensure completion of the process (sequential fermentation).
This project aims to 1) document and characterize the native yeasts in Nova Scotia vineyards, 2) determine their influence on wine quality, alone or in combination with commercial yeast, and 3) grow and store promising native yeast strains to produce mixed starter cultures that can provide the benefits of native yeasts without the risks of fully natural fermentations.
Natural fermentations using grape musts from several Nova Scotia vineyards have been carried out, which varied greatly in their content of residual sugars, ethanol, glycerol and certain phenolics. It was confirmed that Non-Saccharomyces yeasts were active early in fermentation, but decreased with ongoing fermentation. The native yeasts were identified by DNA sequencing and characterized with respect to their fermentative properties. Promising Saccharomyces and non-Saccharomyces yeast stains were selected for fermentation trials. The flavour and aroma of the products of the natural fermentations were also assessed by a wine panel in order to link the quality of the final products to the occurrence of specific assemblages of native yeasts.
High-throughput sequencing revealed a decrease in fungal diversity after fermentation. Some dominant fungal species in pre-fermented musts were replaced by Saccharomyces species in successful spontaneous fermentations. Vineyards support diverse and distinctive communities of fermentative yeasts, including Saccharomyces species, which may be commercial or native yeast strains. A home-use test approach was used to conduct sensory evaluation of eighteen fermented samples. The average overall liking scores ranged from 3.25 to 7.25 out of 9. Some samples were described as very sweet with fruity, licorice aromas indicating that little or no fermentation had occurred whereas the visible sediments on the bottom of some sample containers, indicated that the samples were still being fermented. Overall, the terms used most frequently to describe the samples were sour-weak and sweet-weak. Future sensory evaluation studies will seek to engage wine growers as potential panelists.
The results of this research will allow local winemakers to begin utilizing the native yeasts found in their vineyards to create distinctive wines with qualities reflecting the Nova Scotia wine making region.
- Lihua Fan, Gavin Kernaghan, AAFC Kentville and Mount Saint Vincent University
Activity 14 - Improving sparkling and still wine quality: preventing high volatile acidity, honey off-flavour and other faults through Canadian yeast isolates
In wines, a limited amount of “sweet/honey” flavour contributes to the complexity of wine, but at high levels, is considered a fault (Campo et al. 2012). It has been observed by sparkling producers in Canada Ontario that sparkling wines in Ontario produced with Pinot noir grapes (susceptible to sour rot) can have an obvious “sweet/honey” flavour. With sparkling wine production on the rise across Ontario, it is critical that this issue is addressed. Two specific aroma compounds identified in wine that cause this “sweet/honey” off-flavour are Ethylphenyl acetate (EPhA) and Phenylacetic acid PhAA (Campo et al. 2012). Both compounds were reported to contribute to “sweet/honey” off-flavour in wines made from grapes that contain some sour rot (Campo et al. 2012). It is unclear as to when these problem compounds originate, and the direct linkage to sour rot development in grapes. It could be that the grapes have high levels of the precursor, and the sour rot microbial complex acts on the precursor contributing to the “sweet/honey” off-flavour when sour rot develops in the fruit. Alternatively, commercial yeast could be forming these compounds during fermentation when acetic acid levels are high in the starting must (such as when sour rot grapes are present) through esterification reactions with other fermentation metabolites.
PhAA is a plant-growth regulator so it could possibly be produced in grapes susceptible to sour rot as a growth response to an alteration of the surface of the grapes. No studies to analyze the grapes before, and after, sour rot to measure the precursor PhAA and the metabolite EpHA have been carried out. We hypothesize that these compounds are high in grapes as they begin to break down internally from sour rot, and then are transferred to the must and ultimately the wine. Studies have not been carried out on Ontario varieties in Canada prone to sour rot used in red table wines and sparkling wines (Pinot noir). Consumer threshold levels have been identified in wines made from the Portuguese red grape variety Trincaderia. However, the “sweet/honey” off- flavour also appears to be increased by the common nitrogen additive Diammonium phosphate (DAP) during fermentation and lees aging. It is essential we test grapes harvested for sparkling wine that are known to be susceptible to sour rot, for the precursor and the metabolite (Torrea et al. 2011, Campo et al. 2012). The thin-skinned Pinot noir is particularly susceptible to sour rot, widely planted across Canada in Ontario and used in sparkling wine production.
One way to improve quality and further provide a sense of regional identity to Canadian wine is through the use of locally isolated yeast. Inglis has been characterizing a natural yeast isolated from the skin of local Icewine grapes in Ontario. Although the yeast was not a sufficiently strong yeast to ferment above 9% v/v ethanol in Icewine, it has proven beneficial for appassimento wine production in that it is a low producer of the oxidative compounds acetic acid, ethyl acetate and acetaldehyde while also offering a favorable, unique flavor profile to the wines and over 16%v/v ethanol. This project has the opportunity to fully characterize the commercial potential of locally isolated yeasts, one of which is already known to produce lower levels of acetic acid, acetaldehyde and ethyl acetate during fermentation. This yeast also appears to consume large quantities of acetic acid during the fermentation, and may further reduce the formation of “sweet/honey” off-flavour. Applications of this yeast may extend beyond appassimento wine production to still red wine production, sparkling base wine production and a specific application to reduce negative impacts from a percentage of sour rot fruit on overall wine quality.
The overall objectives of this project are to identify if two “sweet/honey” off-flavours caused by ethyl phenylacetate (EPhA) and phenylacetic acid (PhAA) are present in Pinot noir grapes as a result of sour rot infection as well as in sparkling and still wines fermented from those grapes. We will test consumer acceptance of the compounds in red and sparkling wines; and test if natural indigenous yeast isolates from Canadian vineyards can remove the compounds along with acetic acid. An indigenous yeast isolated from an Ontario vineyard will be trialed for commercial scale red wine production.
- Belinda Kemp, CCOVI at Brock University
Activity 15 - Plant Parasitic Nematodes
Plant-parasitic nematodes (PPNs) are microscopic soil-dwelling worms that parasitize plant roots. Some species are important but often overlooked pests of wine grapes in many of the major wine-producing regions of the world. While several types of PPNs were known to be present in Okanagan Valley vineyards, their actual distributions and impacts on vine growth under Okanagan growing conditions were poorly known. Therefore, the objectives of this ongoing research project were to: (1) Determine the distribution of key species of PPNs in Okanagan vineyards; (2) Correlate PPN populations within experimental vineyard blocks with measures of vine vigour and the incidence of other diseases; and (3) Develop pure cultures of key PPN species and perform controlled inoculation experiments to experimentally measure effects of the nematodes on vine growth and susceptibility to other diseases. A fourth objective was to perform an initial survey of PPNs found in Nova Scotia vineyards.
Progress through 2020 includes completion of a comprehensive survey that revealed that a species known as the ring nematode, Mesocriconema xenoplax, is present in approximately 80% of Okanagan vineyards. This is significant because previous research has shown that this nematode can impair the growth of young grapevines. Ring nematodes were also found to be the most prominent group of PPNs in Nova Scotia vineyards as well, but it was less frequently found than in the Okanagan Valley. Research towards Objective 2 includes multi-year monitoring of PPN populations in relation to vine water stress measurements in field experiments testing alternative irrigation scheduling methods and compost amendments. Early results indicate that scheduling irrigation according to canopy temperatures may result in the buildup of larger ring nematode populations than when irrigation is applied on a three day per week schedule. Ongoing research will attempt to determine why the ring nematode populations respond differently to the two types of irrigation scheduling, and if this change in population size has feedback effects on vine responses. Regarding Objective 3, multiple multi-year controlled inoculation experiments have been set up to assess the effects of ring nematodes on susceptibility to trunk disease pathogens, and results from these experiments are pending. Other controlled inoculation experiments that were completed have shown that the most common species of root-lesion nematode in temperate climate horticulture, Pratylenchus penetrans, is actually not able to parasitize grapevines. Due to its widespread occurrence, eliminating this species from the list of potential pest species helps to sharpen the focus of future research and management of PPNs in cool-climate vineyards.
- Tom Forge, AAFC Summerland
Activity 16 - Novel approaches to IPM strategies for climbing cutworm in grapevines
- Deborah Henderson, Kwantlen Polytechnic University
Activity 17 - Grape & Wine Leafhopper Management
Leafhoppers are economically important pests of grapevines in Canada. Feeding by nymphs and adults causes the death of individual leaf cells, resulting in reduced photosynthetic activity and delayed ripening of fruit. Control is currently achieved largely with applications of insecticides, but predators and parasitoids play a significant role and there are opportunities to provide alternatives that are organic or more sustainable. An explanation for the greater abundance of Virginia creeper leafhopper (VCL) in BC compared to elsewhere in Canada is the reduced numbers of its Mymarid egg parasitoid Anagrus daanei. A recent dramatic decrease in numbers of VCL in certain areas of the Okanagan suggests that another species of egg parasitoid might have arrived, or survival of A. daanei might have improved with the arrival of another leafhopper species that serves as an alternative winter host. Comprehensive parasitoid and host plant association surveys in BC and ON will help determine if parasitoid species can be introduced to affected regions, or if host plants supportive of alternative leafhopper hosts can be utilized to enhance parasitism. Identifying Anagrus species based on morphological characteristics is difficult due to their small size and similar appearance. For this study, we will utilize genetic molecular techniques in addition to morphological characteristics for the accurate identification of egg parasitoids and their leafhopper hosts.
New insecticides for the control of leafhoppers are desirable to prevent resistance development, as replacements to neonicotinoids that are of concern for their effects on non-target species, and as materials more suitable for organic or sustainable production (e.g. less toxic to Anagrus parasitoids). Horticultural oils are of interest as stand-alone products or to enhance the activity of insecticides. Efficacy data generated in the laboratory and field will contribute to the registration of novel pesticides more suited to the sustainable management of leafhoppers. From previous research we showed that certain fungicides, surfactants, and plant essential oils were highly antifeedant or repellant to grape leafhoppers. Additional study is required to evaluate the deterrent activity of several newly available commercial materials (e.g. BioRepel with 10% garlic oil) derived from plant essential oils and to assess their activity in the field. Ovipositing leafhoppers also assess grapevines for suitability based on nutrition and water status, and studies from California showed lower densities on vines undergoing moderate deficit irrigation for 3-6 weeks beginning at berry set. An average reduction in oviposition of 44% was also achieved, with additional mortality recorded during development of the nymphs. For this study we plan to evaluate the effect of deficit irrigation on leafhopper populations and vine physiology and fruit yield and quality. The various components of this proposed research will contribute to the development of a sustainable management program for leafhoppers on grapes in Canada.
- Tom Lowery, AAFC Summerland
Activity 18 - Mitigation of infestations of multi-coloured Asian lady beetle (MALB)
This project is complete.
- Wendy McFadden-Smith, CCOVI at Brock University
Activity 19 - Using ground cover to control soil bourne pathogens in grapevines
The role of groundcover in pathogen control is largely unknown, yet it is well known plants can alter the composition of soil fungal communities. Increasing the biodiversity of Canadian Vineyards above ground may have advantages beyond pathogen suppression, including improved nutrient retention, improved soil structure, reduced herbivory. These ecosystem services will become increasingly important as growers experience the effects of future climate regimes. Although grape growers are eager to exploit cover crops as biofumigants there is insufficient evidence to recommend particular crops or combinations. We will test the role of plant identity in cover crops in viticulture on the incidence and abundance of common trunk fungal diseases.
We are testing the effect of various cover cropping systems on soil microbial communities and disease incidence. Specifically, we are interested in whether different brassicas, which are known to confer disease resistance, are equally effective. We are also interested in how they affect beneficial fungi. We are exploring these topics in greenhouse and field settings. We are also interested in how cover crops can facilitate the spread of inoculant microbes – this work is just being started. Finally, we are looking at the effect of cover crop composition and biodiversity on soil microbial communities and disease incidence.
- Miranda Hart, University of British Columbia-Okanagan
Activity 20 - Crown Gall Disease of grapevines: identification, bio-control and sustainable management strategies
Three different grapevine cultivars from the same nursery were analyzed for presence of A. vitis. The bacteria were unevenly distributed within the vines, with samples having bacteria present at the roots, the base of the rootstock, the graft union and/or the scion.
Five potential biological controls to combat grapevine crown gall were identified. All five isolates showed consistent inhibitory properties when used in three different screens against A. vitis in plate assays. However, when the same strains were inoculated into grapevine stems using needles, they did not prevent gall formation. Additional plant experiments with modified conditions will be conducted to address this, and the biocontrols will also be used as soil inoculum.
We found that fungal isolates belonging to Trichoderma sp. were able to reduce crown gall bacteria on plates. The same fungal isolates constitute the active ingredient of the pesticide RootshieldR. The product was successfully infiltrated into grapevine canes and we were able to re-isolate the product from all parts of the cane. This is an important find, as this may lead to an application where grapevines can be immunized against crown gall in nurseries.
Six A. vitis strains were isolated from local vineyards and characterized. All strains were able to cause galls similar to the control strain CG47. Local A. vitis strains from the Okanagan have not been isolated to date, but are an important basis for the project to test the effect of any potential biocontrols that have also been isolated from Okanagan vineyards.
Vineyard soil was sampled in Spring and Fall of 2020 and analyzed for A. vitis presence. Very few bacteria were found, and there were no differences between any of the treatments (composts or no compost). This is surprising as the vineyard shows crown gall symptoms. It is possible that bacteria are less abundant in the soil at certain dates or present in different locations, or that the bacterial population in the soil decreases with increasing vineyard age.
All three composts increased soil potassium and magnesium levels. Leaf greenness was also higher in compost treatments. Berry titratable acidity and average weight was higher in berries where the winery compost was applied.
A new experimental vineyard was established in a location with severe crown gall disease. The old vines were removed and replanted with nursery stock. Compost and soil mount treatments were applied. Data will be collected as for the commercial vineyard as they become available.
- Louise Nelson, University of British Columbia - Okanagan
Activity 21 - Grape & Wine Trunk Diseases
The long term economic viability of the grapevine industry relies on healthy planting material and effective disease management strategies in vineyards. Grapevine trunk diseases (GTD) are considered one of the most important biotic factor limiting both yield and vineyards’ lifespan not only in Canada but worldwide. Previous studies conducted by the Plant Pathology laboratory at the Summerland Research and Development Centre (SuRDC) since 2010 have significantly contributed to a better understanding on regards the current status of GTD in British Columbia (BC), laying the foundation for the development of effective disease control strategies. However, contrary to most grape-growing countries around the world, neither cultural practices nor registered products (chemical or biological) are currently available to mitigate the impact of these diseases in Canada. Therefore, and building on previous work, the main objective of this research project is to develop and implement effective management strategies against GTD in both young and mature vineyards as well as in grapevine nurseries in Canada. This study will investigate cultural practices such as best pruning time to mitigate GTD infection and will also focus on potential environment-friendly biological control options. Additionally, this research aims to demystify the role that abiotic and biotic stress factors, including water stress, over-cropping, j-rooting, and nematodes play on GTD disease development in young vineyards. This research aims to provide information to the Canadian grape-industry about best planting and growing conditions to minimize the impact of GTD. Despite the difficulties and work limitations experienced since mid-March of 2020 due to COViD-19, continuous progress has been made in all the objectives during the 2020-2021 work year.
- Jose Urbez-Torres, AAFC Summerland
Activity 22 - Grape & Wine Terroir and Precision
Most work planned for Activity 22 progressed on track, but some work not conducted due to covid restrictions, and has been postponed until 2021 or 2022. A summary of the work conducted for Activity 22 objectives:
1. GIS update and soil carbon survey. Detailed soil characterization and mapping was conducted for 20 new vineyards in the Okanagan Valley and added to the GIS. Vineyard soil carbon levels are being determined for all growing regions of the Okanagan and Similkameen Valleys. In 2020, detailed soil sampling was conducted in 20 vineyards and in 10 nearby natural sites. Soil was sampled from within and between vineyard rows, and at two depths, and the detailed analysis was conducted at the BC Ministry of Environment lab. Statistical analysis to determine relationships among soil characteristics and with management practices is in progress. Development and description of geographical indications for BC has continued in collaboration with industry groups.
2. Interactive effects of seasonally timed water stress and cluster exposure. A field experiment planned for 2020 was not conducted due to covid restrictions. This experiment will be conducted in 2021 contingent on covid restrictions.
3. Drone based imaging to guide precision management of irrigation and nitrogen. Thermal, RGB and multispectral imagers were co-mounted on a large drone and programmed for coordinated imaging. Thirty-six test flights were successfully conducted at SuRDC. Fourteen imaging flights were conducted in in commercial vineyards in the Okanagan Valley to assess grapevine N status in experiments established in Activity 11 (K Usher, PI). Limited ground truthing was conducted due to covid restrictions. This work will continue in 2021 contingent on covid restrictions.
4. Drone and ground based imaging to diagnose grapevine diseases. Thermal and multispectral imaging was conducted in 10 drone flights in a commercial vineyard to assess trunk disease impacts and remedial treatments. Thirteen imaging flights were conducted to evaluate our spectral diagnostic model for detecting leaf roll virus infections. This imaging work is linked to Activity 21 for trunk disease, and Activity 2 for virus (JR Urbez Torres, PI). Ground-truthing measurements of leaf gas exchange, leaf reflected spectra, and leaf pigments were not conducted due to covid restrictions. Data analysis has included development of point cloud images to sample and characterize emitted and reflected spectra from vertical grapevine canopies.
- Pat Bowen, AAFC Summerland
Thank you to our funding Partners:
Agriculture & Agri-Food Canada through the Canadian Agricultural Partnership