Year 4 Grape & Wine Science Cluster Research Update

Posted Sep 7th, 2022 in Cluster Updates & Events, Research

Year 4 Grape & Wine Science Cluster Research Update

As we close the fourth 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, the British Columbia Wine Grape Council, Grape Growers of Ontario, Ontario Grape and Wine Research Inc., Conseil des Vins du Québec, Nova Scotia Department of Agriculture, and the Grape Growers Association of Nova Scotia, along with our various industry partners, for funding this research. We look forward to learning more over the final year of the program. For more information, please contact us

Activity 2 - Grape and Wine Viruses in British Columbia

Research contained in Activity #2 of the CGCN project Fostering sustainable Growth of the Canadian Grape and Wine Sector addresses the need to develop management strategies to mitigate economic damage to the wine grape industry from major grapevine viruses. Main areas of research include studies of the effects of Grapevine leafroll associated virus (GLRaV) and Grapevine red blotch virus (GRBV) on plant health and fruit quality; strategies to mitigate virus infections (e.g., testing and rogueing); and methods to manage virus vectors in British Columbia. In spite of the negative impacts of ongoing COVID restrictions, staffing changes, and the extreme summer heat during the summer of 2021, significant progress was achieved on all areas of study.

Data on the health and productivity of red cultivars collected for the 7th year in 2021 continued to show a reduction in soluble solids (Brix) from GLRaV-3 infected vines compared against healthy vines of ~ 1.2 Brix. In addition, results from the 2021 harvest showed a 10% yield reduction in GLRaV-3 infected vines. Evaluation of the effects of GLRaV on Sauvignon Blanc, Chardonnay and Semillon indicated no statistically significant differences in plant health or fruit quality for these white cultivars as measured by yield, total soluble solids (Brix), pH, titratable acidity, photosynthesis rate, pruning weights, and bud hardiness. Evaluation of the impacts of GRBV on the health and performance of Cabernet Sauvignon under BC conditions showed a significantly lower yield and a reduction up to 4 Brix compared to healthy vines. Field surveys for Grapevine Pinot Gris Virus (GPGV) found it to be very prevalent throughout BC vineyards, but almost entirely in the asymptomatic form or strain, with only two vineyards being confirmed to have the damaging symptomatic strain. Sequencing of 24 GPGV isolates from BC, including 10 full genomes has been completed and phylogenetic analyses are ongoing to determine correlations between BC isolates and worldwide isolates available in the GenBank database.

Research started in 2021 looking at crop thinning as a potential tool to minimize the impact of GLRaV-3 and GRBV on red grape cultivars was completed. Crop thinning is a standard cultural practice used by growers aiming to increase fruit quality by dropping certain amount of fruit. More resources are put by the vine in less fruit increasing the quality of fruit left in the vine. Results from 2021 trials showed crop thinning can potentially assist to reduce the negative effects that GLRaV-3 has on Merlot and Cabernet Sauvignon but show no effects on GRBV.

Building on earlier work that identified species of treehopper capable of transmitting GRBV to artificial diet (Kahl et al. 2021. Canadian J. Plant Path. June 2021) four species of treehoppers have been identified from the Okanagan-Similkameen, with Stictocephala brevistylus being a new record for BC. Sweep net samples collected over the summer of 2021 from vineyard blocks with documented spread of GRBV failed, however, to collect treehoppers from any sites on any dates. Sampling will be carried out again during 2022 with a shift to include a focus on planthopper adults and nymphs as possible vectors of GRBV. Assessment and mapping of GLRaV and counts of mealybug and scale vectors in adjoining virus source blocks was carried out again during fall 2021 in 15 study blocks. Mapping and nearest neighbor calculations showed that 97% of new infections occurred within 50m of the infected virus source block; correlations of block infection rates showed that grape mealybug appear to be more important vectors than soft scale (European fruit lecanium scale and cottony grape scale).

Contributing to the management of cottony grape scale, we have reported for the first time from BC species identifications and high rates of parasitism and predation from 13 different parasitoid species reared from scale nymphs and 6 species from adult scales. Final assessments of scale counts and parasitism from the field study initiated in 2019 to evaluate the long-term impact of the neonicotinoid ClutchTM and the pyrethroid PounceTM showed a lingering effect. Nearly twice as many wintering scale were found in plots that had been treated with Clutch compared with the plots sprayed with the pyrethroid Pounce; numbers of scale nymphs per leaf averaged 1.25 in the Clutch plots compared to about half that number in the Pounce plots. Parasitism rates were not significantly different for wintered scale collected in late spring. More individual parasitoids of three species were recovered on average, however, from parasitized scales from the Pounce plots (2.59) versus the Clutch plots (1.07) were only a single species was recovered. The results of this long-term study support the need for alternative methods to manage vectors of GLRaV, including insecticides that are more compatible with integrated pest management. To this end, field and greenhouse spray trials were carried out in 2021 and there are plans to expand this effort in 2022. Approximately 600 potted vines have been readied for greenhouse trials and large numbers of wintered cottony grape scale are available at various stages of development to provide the required crawler stages needed to infest each plant.

- José Urbez Torres and Tom Lowery, AAFC Summerland

Activity 3 - Grapevine Virus Diseases and Virus Vector Control

  • Petiole samples were collected in 2021 from individual vines at 2 of the vineyards where individual vines were sampled in 2018-2020 (Chardonnay, Vidal and Cabernet franc).  Samples were submitted to CCOVI lab for testing for GLRV-3 and GRBV.
  • Fruit was collected from individual vines with GLRaV-3, GRBV and GLRaV-3+GRBV as well as virus free vines at 2 sites (Chardonnay and Pinot noir).  Yield, cluster number, weight per cluster and average berry weight were determined.  Soluble solids, pH and titratable acidity were determined on juice for each vine.  Triplicate micro-ferments were conducted with fruit from individual vines.  Fermentation kinetics were monitored until MLA was complete.  Wine quality parameters (Brix, free and total SO2, malic acid, yeast assimilable nitrogen, acetic acid and anthocyanins and phenolics in Pinot noir and hyroxycinnamic acids in Chardonnay) are currently being determined.
  • Vines infected with GLRaV-3, GRBV and GLRaV-3+GRBV as well as virus-free vines were sampled monthly at 3 vineyards (Chardonnay, Pinot noir and Vidal) starting in November to determine effects of solo and combined infections on bud cold hardiness.  Vine vigour was evaluated by pruning weights.
  • Mealybug and scale were monitored at 4 sites with double-sided tape and trunk counts throughout the growing season.
  • A mycorrhizal preparation (BioCult) was applied to Chardonnay vines with and without GLRaV-3.  Fruit from individual vines was harvested and yield, number of clusters.
  • Determine the impact of asymptomatic and symptomatic infections of GPGV on fruit yield and quality and GPGV genetic diversity.
  • Determine putative vectors of GRBV.
  • Insecticides registered in grapes were evaluated for activity vs buffalo treehopper.
- Justin Renkema and Wendy McFadden-Smith, AAFC Vineland and CCOVI at Brock University

Activity 4 - Evaluation of Viruses

Part I: Impact of key economic grapevine viruses on vine performance and fruit quality 

In 2021-2022, efforts focused on the virus trial established in the research vineyard located at the Kentville Research and Development Centre (KRDC) in late May 2020, that evaluated vine performance in Grapevine Leafroll associated Virus-3 (GLRaV-3) and Grapevine Red Blotch Virus (GRBV) infected plants. Fifty-two vines (26 infected and 26 nearby control vines), spread across three cultivars (New York Muscat, Marquette and Vidal Blanc) were followed. New York Muscat and Vidal Blanc infected vines had grapevine leaf roll virus 3 (GLRV-3) while the Marquette infected vines had grapevine red blotch virus (GRBV). Samples from individual vines (4 leaves with petioles intact/vine) were collected in late August and processed, using RT-PCR, to confirm virus status in each of the 52 vines. Vine performance consisted of monitoring phenology, vine architecture (%blind nodes, % weak shoots, shoots from the head, bull cane diameter), yield, brix and TA, chlorophyll and gas exchange, and dormant pruning weights. All vines-of-interest were inspected weekly to bi-weekly, photographed, and any observed symptoms recorded. Grape samples from all 52 vines (both infected and non-infected) were also collected to evaluate the effects of virus infection on grape chemical composition. As in 2020, must from the grapes was extracted and then analyzed for sugar, acid and volatile composition using HPLC and GC-MS. Samples were also frozen at -80C for subsequent phenolics assessment. Preliminary results showed a significant larger berry size in Vidal blanc (2020; p = 0.02). Other interesting trends suggested lower brix in both years and across all varieties (approx. 1 °); both Marquette and Vidal blanc showed higher TA (2021) (p = 0.06) and lower chlorophyll in Vidal blanc in 2020 samples (p = 0.06) and Marquette in 2021 (p = 0.01).  Commercial virus screening surveys in commercial blocks were completed in 2020. In collaboration with AAFC-SuRDC, CCOVI, and CFIA researchers, AAFC-KRDC efforts focused on contributing to NGS screening of existing NS samples and dormant canes collected in February 2022. Provincial collaborators (Perennia) continued screening in newly established blocks in 2021 and data was shared with D. Moreau and the NS industry. Of the viruses detected, GLRaV-3 is the most prevalent, followed by GPGV, GRBV, GLRaV-1, then GFLV. Additionally, in June of 2021 a dedicated virus vineyard containing two separate grape virus trials was successfully installed. This initiative had been previously delayed as a result of the pandemic. In the first trial 3 hybrid cultivars (Seyval Blanc, Marechal Foch and New York Muscat), both with and without GLRaV-3, and the second trial with Marquette vines, both with and without GRBD, were established. Vine performance data began in the fall, looking at chlorophyll levels, and over the winter, looking and dormant pruning weights.

Weekly inspections for known vectors were conducted from the end of May through to mid-October 2021, in the KRDC research vineyard and four commercial vineyard blocks. Additional commercial sites were inspected when on location. Although observed in previous years, Grape mealybug (Pseudococcus maritimus) was not observed in the KRDC research vineyard  and remain very low and localized (only detected at 2 commercial sites @ 475-500 GDD (mid-July)). Increased incidence of Fruit lecanium scale (Parthenolecanium corni) was observed in commercial sites but did not correlate with leafroll virus status. To date, numbers do not warrant sprays to manage. The potential vector, Buffalo Treehopper (Stictocephala alta) was commonly observed in sweeps within laneways. Cane girdling was observed in blocks with confirmed GRBV but insects were not observed feeding. The risk of increased incidence of grapevine viruses remains linked to infected nursery material, since vector pressure remains very low in Nova Scotia. Access to virus-free plant material should remain a major priority. Communications are ongoing with grape growers, extension specialists, researchers, and other industry stakeholders throughout the growing season through pest updates, verbal and written report of activities to the AAFC ASC-12 Canadian Grapevine Certification Network and presentation made to the GGANS Best Practices virtual workshop, GGANS AGM, and the Nova Scotia Community College ‘Cool Climate Wine and Viticulture Program’ that included students and teaching staff.

Part II: Distribution and impact of emergent and invasive insect pest species in the context of viticultural expansion in Nova Scotia.

(1)   Determine incidence, distribution, and movement of Phylloxera
(2)   Monitor commercial grape for potential endemic and invasive insect threats in Nova Scotia.

Objective 1: In early May 2021, field trials for phylloxera were initiated. An intensive trapping study (40 non-invasive ‘bucket’ traps) was established in the KRDC research vineyard to assess timing of emergence and movement throughout the vineyard and between various cultivars that include both hybrids and vinifera. Bi-weekly trap collections to establish soil emergence counts and observed leaf galling, were related to a number of measured factors that include vine phenology, ambient and soil temperatures, tissue analysis, NDVI measurements, and fruit yield and quality. Incidence and overall level of infestations appear to be on the increase, although we have not had time to process all data yet. Preliminary observations showed sustained catches for soil emerging stages to be in mid-June 2021 and correlating with soil temperatures >20°C and rapid shoot and inflorescence development. Throughout the season, total trap captures were highly variable by variety (29 - 97,970), suggesting possible differences in pest preference between varieties. Traps located next to L’Acadie blanc vines saw a total of 29 soil emerging phylloxera throughout the season versus 97,970 in Marquette. Continued research is needed to monitor the long-term implications of high pest numbers on vine performance and if local populations present a risk to neighboring varieties that may be less susceptible. Movement was observed between varieties within the KRDC trial and thought to be wind influenced given the direction of spread. Similar to 2020, both ambient soil and air temperatures were statistically correlated with the soil emergence counts. Soil temperatures between 21 and 25°C at a depth of 30 cm were correlated with the highest emergence levels. These temperatures were consistent with previously reported temperatures for nymph survival (21-28°C). Air temperatures were also significantly correlated with emerging counts but, not unexpectedly, were more variable than soil temperatures. Vine phenology observations were also correlated with soil emergence counts using regression analysis. Phenology stages around rapid shoot and inflorescence development and berry development were associated with the highest emergence numbers. Weekly phylloxera trapping (44 non-invasive ‘bucket’ traps in total across all sites) was also conducted in four ‘leaf thinning trial blocks’ within commercial vineyards to assess potential impact on counts for both root- and leaf-feeding forms. Given the warm weather, sampling was extended until the end of October 2021, at which time the traps were removed from the field. Processing of trap contents were completed in February 2022 and data analysis ongoing. Incidence and overall level of infestations each year appear to be on the increase. The greatest threat remains for producers of non-conventional production systems, where there are no effective control products available for use on this pest. Research is needed to evaluate alternative control options.

Objective 2: Monitoring for other invasive and emerging species was delayed and did not start until July due to some unforeseen issues in 2021. Commercial vineyard monitoring efforts for other invasive and emerging insect pests included grower education and increasing awareness of potential pests and their associated risks. Written updates were produced and disseminated to growers through the Grape Growers Association of Nova Scotia.  A detailed newsletter provided identification and general biology information to growers on the invasive Japanese beetle (Popillia japonica) and Grape berry moth (Paralobesia viteana Clemens). Monitoring in 2021 for presence of Japanese beetle in vineyards has confirmed the continued spread in distribution from the recorded site of first detection and establishment within the province. Discussions around best management practices are ongoing with grape growers. Despite a suspected first Grape berry moth find in 2020, where we were not able to confirm species due to the compromised integrity of the sample at the time of receipt,  no specimens were observed in 2021. Various leafrollers were collected and reared, with the majority identified as Redbanded leafroller (Argyrotaenia velutinana), a common Tortricid in Nova Scotia. One surprise this year were spotted wing drosophila (Drosophila suzukii) numbers and observed damage in vinifera grapes. Typically this has not been considered a pest of interest in grape and damage may have been a result of multiple factors that included warm, humid temperatures that supported higher populations and fruit (especially thinner skinned varieties…mostly vinifera) left to hang longer with the favourable Fall conditions. Higher than usual levels of sour rot were observed and may have been affected by the wounds caused by egg-laying that can contribute to development of the disease. Given changing climate trends, spotted wing drosophila should be monitored from veraison and on. Damage was sufficient to cause some growers to want to schedule maintenance sprays but this would present challenges around harvest. Work is needed to determine best timing of management tactics. There remains a growing interest in incorporating wildflower plots as refuges for beneficial species, especially in organic production systems.  As in previous years, specimens and/or images of pest species of interest (not vectors) were routinely received by growers and identified. Commercial vineyard monitoring efforts included grower education and efforts to increase awareness of potential pests and their associated risks. Communications regarding progress in both activities are ongoing with grape growers, extension specialists, researchers, and other industry stakeholders throughout the growing season through pest updates, verbal and written report of activities to the AAFC ASC-12 Canadian Grapevine Certification Network and presentation made to the GGANS Best Practices virtual workshop.

- 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. Three years of LTE monitoring in Quebec demonstrated that there was great variability in LTE values between vineyards and grape cultivars. In addition, rustic hybrid cultivars 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 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 five vineyards across Quebec. A first site was evaluated in the fall of 2018 and the data was collected during the 2019 season. We can note that the geotextiles influence the environment under them, keeping the temperature around the vines significantly higher than outside, especially in very cold weather and when a snow cover is present. The temperatures under the geotextiles, the timing of phenological stages and the yield components were not influenced by the type of geotextiles. The timing of installation and removal had a small impact on the yield and yield component depending on the year, site and cultivar. In some condition, an early installation/early removal treatment had a higher cluster number/vine than the late installation/late removal treatment. Higher yield/vine was also observed in some conditions on the late installation/late removal compared to the late installation/early removal treatment.

 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. This study has demonstrated that rootstocks may affect cold-hardy hybrids in different ways and some of them showed higher potential than others for use under eastern North American conditions. Our results obtained for Frontenac, Frontenac blanc and Marquette did not show a significant effect of rootstock on bud survival, vine physiology during the spring nor for the remainder of the season but the grapevine vigor was affected by rootstock, where lower vigor was observed with Riparia Gloire. For vine varieties known to have magnesium deficiencies, such as Frontenac, the use of rootstock 3309 reduces this deficiency. Rootstocks may also affect some yield components and fruit composition parameters, but the effect of growing season (vintage) is predominant. The significant impacts of grafting on fruits are on wine appreciation where higher aromas were noted on wines produced with grapes on grafted vines compared to own-rooted vines. The wines made from own-rooted vines were the least popular. Thus, the results of this project allow us to propose the use of certain rootstocks, such as 3309 and 101-14, which are well adapted to soil and climatic conditions. Some growers have already asked nurserymen to prepare hybrid plants with these rootstocks. In the coming years, the use of rootstocks with hybrids could increase. Growers will be able to use the results of this project to select the desired rootstock.

- Caroline Provost, Centre de Recherche agroalimentaire de Mirabel (CRAM)

Activity 6 - Grape & Wine Grapevine Hardiness

Carl Bogdanoff, the Principal Investigator for Activity 6 retired June 30, 2021.  As a result, research work on some objectives continued on a limited bases over this reporting period.  The following is a summary of research conducted for 2021 – 2022.

Objective 1  Evaluation & modification of vineyard management practices.

In this objective there are four multi‐year field experiments.

Expt 1 (planted in 2017) – Investigation of eight rootstocks on the bud and phloem hardiness of Merlot.  Yield, basic fruit composition and bud hardiness data was collected this past winter season.  Collected data will be tabulated, analyzed and summarized later this spring.
Expt 2 (initiated in 2019) – Effects of early season reduced irrigation on the bud hardiness of Merlot.  The second year of this large off-station field experiment was postponed in 2020 and then terminated.    The first year results from 2019 clearly showed that the negative effects of the reduced spring irrigation treatments on yield and ripening outweighed the small positive treatment effect of increased hardiness    (↓ cane wt. → ↑ bud hardiness). 
Expt 3 – (initiated in 2021).  Effects of irrigation/fertigation treatments on vine senescence and hardiness.  This experiment, with irrigation/fertigation treatments ranging from 50% to 150% of normal, is on track with a second year scheduled for the 2022 – 2023 season.  Phenological dates, photosynthesis measurements, leaf senescence, berry composition, yield, pruning weights and bud hardiness measurements have been and will continue to be collected thru April 2023.  This past season’s data will be tabulated, analyzed and summarized later this spring. 
Expt 4 – (initiated in 2021).  Effects of post-harvest defoliation on bud hardiness.  The aim of this experiment is to simulate an early hard frost event, and explore its effect on bud hardiness.  Using 100% irrigated/fertigated guard vines from Expt 3 bud hardiness measurements were made on naturally senescing (control) and de-leafed vines. A second year is planned for 2022 - 2023. This past season’s data will be tabulated, analyzed and summarized later this spring.

Objective 2   Regular posting of varietal bud hardiness measurements and development of predictive bud hardiness models.

Varietal bud hardiness measurements from 72 Okanagan Valley vineyard sites have been and continue to be made every two weeks from late October to early April.  This data is posted to the BCWGC, the BCGA and to local growers, and is used to verify and improve the predictive bud hardiness models that have been developed for eight widely grown cultivars.  The results from these models, a comparison of measured bud hardiness values and model-predicted bud hardiness values, are also posted in a newsletter every two weeks.  The overall combined average R-squared values of predicted against measured hardiness for the past 10 years for each cultivar continues to be better than 97%.  Work to develop an online dashboard to allow growers daily access to predicted hardiness continues with Dr. Wolkovich of UBC.  Bud hardiness data for Chardonnay grown near Vineland Ontario continued but has yet to be assessed and worked into the current Ontario bud hardiness model.

Objective 3  The investigation of grapevine phloem hardiness.  

Much of the proposed goals for this objective have been completed.  A newsletter has been written and a final report is due next year. 

Objective 4   The investigation of grapevine root hardiness. 

Much of the proposed goals for this objective have also been completed.  A final report is due next year.

Objective 5  The examination of grapevine diseases and novel vineyard management practices on winter hardiness. 

Bud hardiness continues to be measured three times from late fall to early spring for all on-going field experiments in Activities 2, 6, 11, 21, & 22. 

Objective 6   Surveying local vineyards to develop new varietal winter hardy clones. 

There are two lines of inquiry in this objective: 1) is to survey local vineyards in the spring for surviving vines after a severe winter (In late December 2021 temperatures in the Kelowna area and north dipped below -27C.  Freeze damage to vineyards is expected, and surviving vines should be identified and tagged this spring.)  and 2) identify vines with above and below average hardiness from a long running field trial to see if it is possible to select and propagate for the hardiness trait (Selections and propagation of vines need to be made this spring).

- Carl Bogdanoff, AAFC Summerland

Activity 7 - Grapevine evaluation and cold hardiness program

Vote 1: AAFC Kentville

Objective 3 – The bud hardiness survey continues to be a popular program in Nova Scotia. Reports are distributed biweekly to the local Grape Growers’ Association of Nova Scotia (GGANS) membership during the dormant season (November – April) and are also posted, as generated, on the CGCN and Perennia (a provincial agriculture development agency) websites. Neither the tail end of the 2020/2021 (i.e., April, 2021) nor the 2021/2022 campaign were impacted by the covid pandemic.

Objective 4 – The bud viability survey continued for another year. This survey again captured the outcome of another winter deep freeze event; the previous such event occurred on February 15, 2020. On January 22, 2022 some sites included in the Nova Scotia bud hardiness survey saw temperature drop below -25 °C. This led to near complete bud mortality in vinifera varieties at the coldest sites. The less hardy hybrid cultivar L’Acadie was also impacted, with as much as 50% mortality at the coldest site. The Pinot Noir vines were not greatly impacted by the event, not because of their hardiness, but because the survey contains only a few sites and these happened to be at the warmest sites. The Marquette cultivar was the least impacted while also being located at two of the coldest sites. Its high hardiness levels translated into minimal bud damage. Work continued on investigating other factors aside from LTE values. Bud moisture content along with peak heights continued to be monitored and will be analyzed in the final year. Additionally, over 600 carbohydrate levels from samples collected over the last 3 years of survey work, as well as from focused trials, were processed and measured via HPLC. A vine balance trial was one of these focused trials: in Marquette and L’Acadie a two-factor trial looked at single vs double cordons and thinned versus control vines. Crop loads varied by 2 to 8 tonnes / acre in L’Acadie and 1 to 3 tonnes per acre in Marquette. Nutrient differences were found in the petioles at veraison, but were only subtle in cane tissue; carbohydrate levels were the lowest in the single cordon thinned treatments, possibly on account of higher vigour, but hardiness levels were minimally impacted. In a similar trial looking at the impact of early vs late harvest timing in Riesling and Vidal grapes, carbohydrate and bud hardiness levels were significantly higher in early harvested vines. Early harvested vines also had higher leaf petiole potassium levels and began to turn colour and drop before late harvest vines. Finally, two reports, aside from bud hardiness reports, were released in 2021-2022: one examined climate change in Nova Scotia and the projected impact on frost risk, the other looking at the frequency of post-deep freeze events and the results from a post deep freeze pruning trial. Both reports are available on the CGCN website and are in the process of being developed into manuscripts for publication. 

Objective 5 – Chardonnay clones have again been ordered and are tentatively planned to be planted at a grower collaborator site in 2022.

Vote 10: CCOVI, Brock University

Objective 1:

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.(Vote 10)
The project is catching up and getting on schedule after some delays due to sourcing of plant material for the clone x rootstock experimental vineyards and COVID 19 related issues. We have continued to monitor experimental vines for major grapevine viruses. Some vines were removed due to positive tests for virus infection. One vineyard is being monitoring closely because red blotch infection does appear to be spreading via an unknown vector. We plan on working with CCOVI virologist, Dr. Poojari who is involved in another cluster activity on red blotch vector transmission and perform some studies in this block. We replaced some vines that were missing but more likely will need to be replaced in 2022. We began collecting some vine performance and fruit composition data for cultivar combinations planted in 2018 and starting to bear fruit.

3 undergraduate student thesis (C. Findlater, T. Chang, A. Szarek) students are currently working on clone x rootstock studies. Harvest and hardiness data were collected for Chardonnay, Pinot noir and Merlot at the Shenck vineyard location where vines were found clean from viruses and bearing fruit. Research vines were harvested in Fall of 2021 and yield components (no. of clusters, yield/vine, berry weight, cluster weight) were taken for different clone x rootstock combinations. Cold hardiness assessments of these combinations were taken from November to April. Fruit composition is currently being completed analyzed for these cultivars. Preliminary results indicate that clone and rootstock can impact vine performance and fruit composition.  Therefore, fruit composition and/or cold tolerance may be optimized through either clone or rootstock selection in Ontario. However, data collected from young vines in the 4th leaf from the experimental vineyards tend to have higher variability than existing mature commercial vineyards. Therefore, more years of data are necessary to make proper recommendations to industry at this point in time.

 We are concluding the final year of the research conducted using Cabernet franc from a commercial vineyard located in Beamsville, ON Canada. This research was conducted by MSc student, Linxue Zhang who just defended her Thesis (Zhang 2022).  Four clone × rootstock combinations (214/101‐14, 327/101‐14, 327/3309, 327/Riparia Gloire) were used for the study. Differential thermal analysis (DTA) was used to measure cold hardiness in this study. Cold hardiness assessments were performed every 3 weeks throughout the dormant period in order to determine how different Cabernet franc material performed throughout the different stages of dormancy. 5‐bud cane portions were sampled from each experimental unit/clone×rootstock and samples were prepared, and cold hardiness assessed using Differential Thermal Analysis. BudProcessor (Version 1.7.2; Brock University, St. Catharines, ON) was used to process and interpret the LTE data and cold hardiness was calculated as LT50 or median of the LTE data/sample. Normal distribution of data was assessed, followed by Analysis of Variance (ANOVA) using XLSTAT statistical package to identify the significance of LT50 between three different rootstocks, between two clones and between four combinations for each sampling date during winter.

 The effect of clones, rootstocks and their combinations on cold hardiness were assessed for the 2018‐19, 2019‐20 and 2020-21 dormant periods. Clones of Cabernet franc differed with respect to rates of acclimation and deacclimation including maximum hardiness (see Figure 1 below). Clone 327 had greater maximum cold tolerance but was slightly less hardy later in dormancy. Rootstock selection had an impact on cold acclimation, maximum hardiness and cold deacclimation when grafted to Cabernet franc clone 327. 101‐14 vines acclimated the fastest and had the greatest cold hardiness. Cabernet franc clone 327 grafted to C3309 was less cold tolerant than the both 101‐14 and Riparia Gloire throughout much of the dormant period. In some cases, hardiness trends were not consistent at some sampling periods. This demonstrates the complex nature of clone×rootstock interactions as well as cold hardiness × environmental conditions. Primary fruit chemistry is still be analyzed for 2021, but we have found differences in vine performance for the different C. franc clone x rootstock combinations over multiple years. Clone and/or rootstock can impact yield, vine vigour/vine size and crop load. In 2021, Merlot clones did impact some yield components, but fruit composition did not vary much among clone or rootstock combination. Hardiness was impacted by clone and rootstock where some combinations were 1-2C hardier at certain sampling dates, but these data were not statically significant.  Chardonnay and Pinot noir data for 2021 are still being analyzed at the time of this report.

Objective 2:

 We have been studying the effects of some different grapevine genotypes including different cultivars, clones and rootstock combinations and relating cold hardiness differences to changes in metabolites and gene expression. For Cabernet franc, dehydrin proteins were also measured throughout dormancy for all clone x rootstock combinations. No clear relationships were found with increased cold hardiness of clone x rootstock combinations and dehydrins. Temperatures during the dormant period impacted dehydrin changes. Dehydrin levels increased following colder temperatures and were not necessarily correlated to greater cold tolerance but increased following colder temperatures.  We have found that in cold hardy Vitis vinifera grapevines such as Cabernet franc and Riesling that there is poor correlation with a clone’s hardiness and dehydrin levels. However, cold sensitive V. vinifera such as Sauvignon blanc do have good correlations between cold tolerance and dehydrin levels (Hébert-Haché et al. 2021). We have also found through some of our current gene expression x hardiness studies that some cold hardiness genes associated with dehydrins did have higher expression at times during dormancy and were found to improve hardiness in V. vinifera cultivars and with application of Abscisic acid analogs.  This is currently being further investigated with additional gene expression studies and further research to understand associated biochemical changes occurring with cold hardiness responses and to further elucidate cultivar x clone x rootstock interactions.

 MSc candidate, Alexandra Gunn has been involved with cold hardiness and ABA related studies. Our research continues to indicate that post-harvest application of ABA and ABA analogs can also improve cold hardiness in grapevines (Bowen et al 2016, Dami et al 2015, Willwerth and Abrams 2018). However, it was dependent not only on ABA formulation but also concentration and timing of application and the most promising formulations were the ABA analogs. However, it has been noted that in 2020 we did not find the same extent of maintenance of dormancy and delay in cold deacclimation/bud break then we did in past years. This appears to be a strange effect of the seasonal variability of the winter months. Preliminary results in 2021 do indicate that that we ABA and its analogs are improving cold tolerance as in other years of the studies. Data from 2021, further support these results in multiple cultivars including cold hardy hybrids (Marquette), hardy V. vinifera (Riesling, Chardonnay) as well as cold tender V. vinifera (Merlot), particularly with respect to maintenance of hardiness during the deacclimation phase. Therefore, applications of these molecules may lead to improved hardiness throughout dormancy and reduce the vine’s susceptibility to lose hardiness later in dormancy. This may be very beneficial in terms of mitigating the effects of temperature fluctuations that commonly occur during Canadian winters and for greater freeze tolerance for tender V. vinifera cultivars or varieties very susceptible to cold deacclimation such as V. riparia-based varieties such as Marquette.

 Hormone profiling from our latest research indicate that ABA concentrations in buds were higher in the treated vines that had greater cold tolerance during the deacclimation 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 including cold hardiness related genes such as C-repeat binding factor and ICE genes and those associated with dehydrins, aquaporins starch and other carbohydrate metabolism (i.e., raffinose) as examples. We have also observed that different cultivars such as Riesling and Merlot have different changes in gene expression related to cold tolerance and ABA applications. These may potentially be an area of research that demonstrates that genotypes are unique in their ability to not only gain maximum hardiness but also the mechanisms involved during the cold acclimation and deacclimation process including the role of ABA itself. This area of research needs further elucidation through this cluster activity objective and future research.

- Harrison Wright and Jim Willwerth, AAFC Kentville and CCOVI at Brock University

Activity 8 - Canopy Management to reduce disease pressure

In 2021, we conducted the second year of the trials conducted in 2020. Briefly, trials were carried out at two commercial vineyards in plots planted with the grape cultivars Vidal blanc (hybrid varieties) and Seyval blanc (hybrid varieties). 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 cultivars, the following five practices of leafing around the cluster zone were: on 1) one side of the row at nouaison (fruit set; stage 27); 2) two sides of the row at nouaison (fruit set; stage 27) ; 3) one side of the row at veraison (stage 35); 4) two sides of the row at veraison (stage 35); 5) no leafing (control). Microclimate (temperature, relative humidity, leaf wetness, solar radiation, wind speed) 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 % disease severity, cluster weight and brix. The influence of leafing treatments on the different variables were analysed using ANOVA. In 2021, we conducted the first year of the study to evaluate the contribution of leaf removal in the fruiting zone for the control of major grapevine diseases in northern climate. The trial was conducted at two sites planted with Vidal and Seyval blanc grape cultivars. The experimental units consisted of 5 rows of 30 m length and the set-up included three replications per treatment. A total of 6 fungicide application schemes were evaluated based on the number of fungicide applications and yields both in terms of quantity (bunch weight) and quality (% disease and brix). The following fungicide application schemes were evaluated: 1) a calendar-based scheme, with fungicides applied at predefined times; 2) a calendar-based scheme with leaf removal at fruit set on both sides of the rows; 3) a disease risk-based scheme with disease risks estimated according to the phenological stage (vine receptivity) and weather conditions in the vineyard; 4) a disease risk-based scheme with disease risks estimated as in treatment 3 with leaf removal at fruit set on both sides of the rows; 5) a disease risk-based scheme with disease risks estimated according to the phenological stage and weather conditions (microclimate) in the canopy (grape cluster zone) with leaf removal at fruit set on both sides of the rows; 6) a control without fungicide applications. In all the plots with leaf removal, leafing was repeated about 3-4 weeks after the first leaf removal done at fruit set in order to avoid the grapevine compensation.

In conclusion for 2021, leaf removal in the cluster zone as a method of controlling the main grapevine diseases alone has not made it possible to significantly reduce the development of diseases as well as yield losses in terms of both quantity and quality. However, when leafing was combined with tools for estimating disease risks, particularly when risks were estimated from weather conditions in the microclimate (cluster zone), this practice made it possible to significantly reduce the number of fungicide treatments while maintaining the yields. The results obtained in 2021 tend to demonstrate the importance of integrated pest management and the effect of methods which alone do not provide acceptable control but which when combined make it possible to achieve an acceptable level of control while reducing the use synthetic fungicides.

- Odile Carisse and Caroline Provost, AAFC CRDH and Centre de Recherche agroalimentaire de Mirabel (CRAM)

Activity 9 -  Optimization of grape production in Eastern Canada 

Our activity focuses on (i) understanding the impact of temperature on berry ripening in the context of global warming and (ii) understanding the relationship between terroir, berry ripening and wine chemical composition.

Our results on the impact of temperature on berry aroma profile are opening the door to a better understanding of the cultural practices used by growers. In-depth analysis of our data showed that early berry exposure to temperature and/or UV radiation can drastically affect the profile of free and bound aroma in berries. Until now, early developmental stages were largely overlooked with regards of their impact on berry aroma. With our work we showed that they are of primary importance to berry quality at harvest; thus, the impact of berry development prior ripening is durable and can barely be recovered during veraison. This finding, in our opinion, is significant because it will affect how growers conduct vineyard operations early in season.

More interestingly, and this meets the results from the second subactivity, our current results on the relationship between GDD accumulation patterns (long and temperate season vs shorter but warmer season) in L’Acadie blanc seems to point in the same direction as our results from the greenhouse experiment, as it seems that a warmer season favored the accumulation of volatile phenols in berries (harvested in Orleand Island) compared to the cooler season experienced in Nova Scotia. This provides significant finding when it comes to understand terroir and optimize the relationship between terroir and grape varieties, a fine tuning actually very much needed in cold climate viticulture.

-Karine Pedneault, Université Sainte-Anne

Activity 10 - Water and Nutrient management strategies for grapevines and health promoting natural products 

The experiment was executed in 2021 season and all objectives were met.


1. Vermicompost tea and seaweed extract provide some non-yield benefits;

2. Biweekly (8 applications) of 1:12.5 vermicompost/water ratio from June to the end of August provide a good coverage on the vine leaves. This sprays provide a light range of N and evidences for protection against powdery mildew is observed; 

3. 6 applications of 2.5 L/ha seaweed extract (Stella Maris) at EL 12, 15, 18, 29, 35, 41 and 2 soil applications at EL 12 and 15 may provide some benefits;

4. Vermicompost is a great source of N and a moderate rate of 14 ton/ha undevine provide sufficient N to the vine during the growing season (>10% release) with low risk of excess N and losses to the environment.

- Mehdi Sharifi and Francisco Diez, AAFC Summerland and Perennia Agriculture and Food Inc. 

Activity 11 - Grape & Wine Nitrogen Management 

In the third year of field trials, sample collection and chemical analysis were completed for two Nitrogen application experiments on Pinot gris and Cabernet Sauvignon grapevines to evaluate N uptake through foliar urea sprays. Results indicate a significant increase in berry yeast assimilable nitrogen with foliar treatments and minimal effects on vine vigour and fruit basic composition for all three years. These positive results indicate foliar urea application can be successfully used to improve grape and wine quality. Wines were made from the field trials and will undergo sensory analysis when it becomes feasible. Sensory trials from 2020 until the present have been put on hold due to COVID and the logistics of conducting trials with the industry considering the restraints we must observe.

Vine N status and leaf spectral imaging was measured in the N application trials and is being used for calibration of relationships among grapevine canopy temperature, reflected spectra and N status conducted for data from years 1 to 4. Due to the local smoke, aerial imaging flights were reduced to image collection in the fall only. We are currently analyzing data to develop, adjust and refine predictive models for vine N status.  

A new instrument for chemical analysis (capillary electrophoresis) was successfully tested for the rapid detection of amino acids, organic acids, anion and cations. Although this was not a part of the objectives, we will now be able to use it for some analysis.

- Kevin Usher, AAFC Summerland

Activity 12 - TanninAlert: improving red wine quality and consumer acceptance

Over the last decade, the increasing popularity of red wines has driven consumer market growth in Ontario and Canada. Red wine, both foreign and domestic, represents 53% ($4.17 billion) of the $7.85 billion of wine sales in Canada in 2020 (Statista, 2021). However, foreign imports still dominate the red wine market, representing 73% ($3.04 billion) of the red wine sold in Canada ($4.17 billion) in 2020 (Statista 2021). Similar trends are reported in Ontario. Given the overall trend of increased red wine consumption in Ontario and Canada, there is a tremendous opportunity for domestic growth in red wine sales and production. Strategic initiatives that are focused on developing product and process innovations to improve quality are the key to meeting consumer demands and subsequent growth of the industry.

The main objective of the overall Tannin project is to improve Ontario red wine quality by ensuring grape phenolic ripeness is incorporated into harvest decisions. Tannins are one of the most defining components of the quality of red wine. Understanding how to best manage winemaking techniques based on tannin values in the fruit are important steps towards improving red wine quality. This project is developing a unique precision oenology tool for winemakers that measures the maturation of red grapes based on tannin development, specifically “TanninAlert”. The tool analyzes tannin concentration in skins and seeds, separately, for red grapes to evaluate phenolic levels in these grapes.  The values are bench marked against tannin measurements from Ontario red grapes collected over the past seven years and available in a database of skin and seed tannin. Red winemaking guidelines based on tannin concentrations will also be available from the TanninAlert database.

In this past year, the skin and seed tannin values during ripening and at harvest in 2021 were determined for Pinot noir, Cabernet franc, Cabernet sauvignon, Merlot, Syrah, Gamay for addition into the TanninAlert database. Histogram plots of tannin distribution are available for Pinot noir, Cabernet franc and Cabernet sauvignon with seven years of data from 2015-2021 such that ranges for low, medium and high skin and seed tannin have been determined based on the 33rd and 66th percentile of the distribution.  Additional years of data collection is required for Merlot, Syrah and Gamay to establish their histogram distribution due to the lower number of sites sampled compared to the other three red grape varieties.

Tannin management techniques for winemaking in 2021 for Merlot, Syrah and Gamay were determined based on the variable levels of skin and seed tannin measured for each variety. For Merlot, we had an opportunity to trial a mobile flash Détente system concurrently with the industry in Niagara for two treatments, with Flash Détente compared to without flash Détente. Subsequent tannin evolution was then monitored for wines made with 0% Flash Détente, 30% Flash Détente, 70% Flash Détente and 100% Flash Détente. For Syrah, a liquid tannin addition to maintain tannin in wine was trialed post fermentation and post filtration compared to a control wine with no liquid tannin addition. For Gamay, different levels of whole bunches were included in the fermentation at 25%, 50% or 75% compared with control at zero whole bunches, and tannin evolution monitored. Chemical analysis of the juice was completed at the time of fermentation and analysis of the wines are almost complete. The wines have been sulfited and bottled.  Tannin stability was monitored post fermentation and will be tested at 6 months. Syrah wines are showing an increase in extractable tannin after the liquid tannin addition post fermentation but the post filtration additions have not yet been measured. Merlot wines are also showing a tannin increase with Flash Détente treatment.  Extractable tannin increased with the higher percentage of wine made with Flash Detente treated fruit. The extractable tannins in the Gamay wines were below the detectable level in the wines using the MCP assay.

Due to COVID 19 restrictions, no sensory or consumer tests could be performed in 2021 on the 2019 and 2020 wines of Cabernet franc, Cabernet sauvignon, Pinot noir, Gamay, Syrah and Merlot due to university restrictions with concerns with aerosol transmission of COVID 19.

The TanninAlert database continues to be expanded with skin and seed tannin data for each year for each variety. Two winemakers trialed the skin and seed tannin measurement system for TanninAlert in 2021 for Cabernet franc (Cave Spring Vineyards) and Cabernet Sauvignon (Chateau des Charmes). A launch of TanninAlert is planned for late summer/fall of 2022 for Pinot noir, Cabernet sauvignon and Cabernet franc. 

- 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 and Gavin Kernaghan, AAFC Kentville and Mount Saint Vincent 

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 - Unearthing the impacts of plant-parasitic nematodes on grapevine health and productivity

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.

Field-based activities proposed for 2021 proceeded as originally planned, and laboratory-based analyses (nematode species identifications) that were postponed in 2020 due to Covid, were completed in 2021. Two key papers stemming from Objectives 1 (distribution of PPNs among BC vineyards) and 4 (identification and distribution of PPNs among NS vineyards) were published and submitted for publication, respectively in 2021. At the time of reporting the second paper had been accepted for publication and is in-press.

In the original work plan, data collection was scheduled to end in 2021, and 2022 was to be used primarily for data analyses and publication. The re-profiling of funding from 2020 to 2022 will enable data collection from three of the four collaborative field experiments to continue through 2022. This is a fortuitous result of the Covid-19 restrictions in 2020, as data from the compost utilization experiments are indicating an interesting year-to-year population trajectory of dagger nematodes that warrants further monitoring. As well, microplot experiments to test effects of ring nematodes on expression of trunk diseases that were originally to be established in 2020 were finally established in 2021, and 2022 will be needed to collect vine growth response data.  

- Tom Forge, AAFC Summerland

Activity 16 - Novel approaches to IPM strategies for climbing cutworm in grapevines  

Final Report

Click here to read the full report

- Deborah Henderson, Kwantlen Polytechnic University

Activity 17 - Grape & Wine Leafhopper Management

Research contained in Activity #17 of the CGCN project Fostering sustainable Growth of the Canadian Grape and Wine Sector addresses the need to develop management strategies to mitigate economic damage to the wine grape industry from leafhopper pests. Areas of research include studies of the host relationships of Anagrus wasps that parasitize leafhopper eggs with their summer and alternate winter leafhopper hosts, and sustainable methods to manage leafhoppers that includes the use of feeding deterrents and insecticides that are more compatible with integrated pest management. In spite of the negative impacts of ongoing COVID restrictions, staffing changes, and the extreme summer heat during the summer of 2021, significant progress was achieved on all areas of study.

Anagrus egg parasites of leafhopper eggs are the most important natural enemies of leafhoppers. To determine the leafhopper hosts utilized for the winter, these parasitoids and their leafhopper hosts were extracted from dormant woody plant material collected in the Niagara region of ON and from the Okanagan and lower mainland of BC in the spring of 2021. Anagrus parasitoids and leafhoppers were also collected during the growing season from grapevines and alternate summer host plants in both regions. To assist with the identification of these minute wasps, coupled with species identifications based on morphology, genetic sequences and primer sets have been created that allow for accurate and rapid identification by molecular testing. The utility of this technique is highlighted by the ability to simultaneously determine the Anagrus parasitoid and its host egg from leaf dissections. It is hoped that information on the biology of Anagrus parasitoids of grape leafhoppers will allow for cultivation of certain companion plant species or other strategies to preserve and enhance parasitoid populations.

Building on our previous research that found certain strobilurin fungicides and organosilicone surfactants to be highly deterrent to feeding by the Virginia creeper leafhopper (VCL) nymphs, laboratory choice test bioassays have been conducted with a number of essential plant oils, formulated plant essential oils, and various other vineyard spray materials. The laboratory component of this work is now completed and the most active materials will be evaluated in replicated field  spray trials. Oviposition by female leafhoppers and survival of nymphs is affected by the condition and water status of the grapevines. In 2021 we were able for the first time to collect data on leafhopper populations from a replicated deficit irrigation field study conducted by Bowen et al. We are hoping to collect data again in 2022 when we will then be able to complete the statistical analyses. With the addition of one remaining insecticide of interest, the efficacy of ten insecticides more compatible with integrated pest management will have been assessed in lab bioassays. Two or three of the most promising insecticides will be included along with horticultural spray oils in replicated field spray trials in 2022.

COVID and other disruptions will delay data analysis and production of articles and manuscripts, but the research should be on track or nearly so for completion by the project end date. No amendments are anticipated.

- 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.  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

Analysis of grapevines obtained from nurseries showed that crown gall bacteria are present in different cultivars, nurseries and locations on the vine. Because distribution is uneven, commercial testing of grapevine nursery stock before planting is difficult. Roots may test negative because bacteria are located in the scion where testing is not possible because vines need to be planted.

We have identified several bacterial and fungal biocontrols that can inhibit growth of crown gall bacteria in the laboratory. However, experiments in the greenhouse to test the strains did not lead to inhibition of crown gall symptoms or the experiments were unsuccessful. More work to improve the greenhouse methods need to be conducted and more biocontrols isolated and evaluated.

We found that fungal isolates belonging to Trichoderma 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, however, RootshieldR did not prevent the development of galls when tested in a greenhouse experiment.

Compost addition did not change grapevine pruning weight in a greenhouse assay. The effect of compost on crown gall bacteria in the soil is being evaluated. However, the greenhouse assays were not successful in regard to crown gall formation; we were not able to generate galls on grapevine trunks when dormant nursery stock was used. Experiments using canes collected from a local vineyard are underway to test if gall formation can be observed on canes without rootstocks.

Compost addition in an established old vineyard did not change crown gall incidence on trunks of grapevines. The effect of compost on crown gall bacteria in the soil is still being evaluated. Compost increased % nitrogen, % carbon and organic matter in vineyard soil. In addition, compost increased soil micronutrients. Harvest and pruning data could not be evaluated in 2021, as the vineyard was harvested without our knowledge.

Compost addition in a newly established vineyard did not change soil properties, as the composts likely need to be applied for a longer period of time. Grapevines where soil was mounded around the graft union in fall did not develop galls, compared to galls that appeared on two control vines without soil mounds. The experiment will be continued over another growing season.

- Louise Nelson, University of British Columbia - Okanagan

Activity 21 - From nursery to vineyard: Implementation of effective management strategies against grapevine trunk disease in Canada

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.

To date, our team has developed and implemented sensitive and reliable molecular tools for the detection and absolute quantification of GTDs fungi present in ready-to-plant material from nurseries. We have implemented this technology in assessing the health status of grapevine material imported into Canada and shown high levels of infection and different fungi present. This study is the first of its type in Canada and will assist to identify inoculum sources as well as management strategies to mitigate infections at the nursery level.

Work conducted during the 2021-2022 fiscal year has added support to the use of locally found biological control agents (BCAs) in BC to be used to control GTDs. Seven species in the Trichoderma genus have been fully characterized and laboratory, greenhouse and field trials have been completed. Results from these studies showed high efficacy of these species as BCAs. In addition our laboratory has generated required field data, which is being currently used by a private company to complete the registration of the first commercial product (biological, Trichoderma-based) for the control of GTDs in Canada. Furthermore, trials to investigate the use of remedial surgery as a cultural practice in BC to mitigate infection are ongoing and results show 100% vine survival after treatment and return to economically viable production after one year.

Work continue to better understand how abiotic or biotic factors affect disease development on young grapevines. Two greenhouse experiments assessing water stress and nematodes as potential stress factors that can induce disease have been completed. Four field trials investigating how abiotic (water-stress, j-rooting, over-cropping) and biotic (nematodes) stressors affect plant health and disease development are in the 3rd year of study.

Despite the difficulties and work limitations experienced since the start of the pandemic in March 2020 and continued during the 2021-2022 fiscal year, significant progress has been made in all the objectives for the 2021-2022 work year and the project is on track to meet all the deliverables.

- 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 2022. A summary of the work conducted for Activity 22, by objective:

1. GIS update and soil carbon survey. Data analysis for soils sampled from vineyards and natural (native) sites throughout the Okanagan Valley was completed. Analyses included total and microbe-available carbon, cation exchange capacity, and plant nutrients.  The main findings from samples analyzed to date were: zero-tillage viticulture practices, common in BC, are not depleting soil C; and there is a strong relationship between soil C and soil texture regardless of vineyard management practices. These findings reveal the importance of considering soil texture in setting soil C sequestration targets for vineyards. The GIS data layer for soil carbon will be important for setting future sustainability strategies for the industry.  This study will continue in 2022 under the leadership of Dr. Ben-Min Cheng. The original PI for this project, Dr. Pat Bowen, retired in September, 2021. Soil sampling and analysis planned for 2021 that would complete the field work (soil sampling) for soil carbon characterization was not conducted due to administrative delays in early 2021. The sampling work will be conducted in spring 2022, and soil processing and data analysis complete by early 2023, to provide sufficient time for results to be included in the final CAP report.

2. Interactive effects of seasonally timed water stress and cluster exposure.  An experiment planned for 2020 was conducted in 2021 in a commercial vineyard to study the interactive effects of grapevine water stress and fruit cluster exposure.  The experiment was completed as planned and fruit compositional analysis is underway.  Replicate wines were made from each treatment to determine their effects on wine chemistry and sensory characteristics. Sensory evaluation will be conducted in late 2022.  This study will continue in 2022 under the leadership of Dr. Ben-Min Cheng. The original PI for this project, Dr. Pat Bowen, retired in September, 2021.

3. Drone based imaging to guide precision management of irrigation and nitrogen.  Although smoke pollution from forest fires prevented drone flights for most of the 2021 growing season, flights were conducted in September to meet objectives. The flights combined multispectral and thermal imaging (co-mounted imagers). The imaging concentrated on studies of grapevine water stress and N nutrition, the latter in collaboration with K Usher.   Significant data management and analysis of drone-acquired images was accomplished. An analysis procedure was developed using point cloud imagery to determine spectral reflectance and IR emission at different heights of the foliage canopy. This image analysis work is in being conducted by Brad Estergaard and will continue in 2022-2023, under the leadership (PI) of Dr. Ben-Min Cheng. The original PI for this project, Dr. Pat Bowen, retired in September, 2021.

4. Drone and ground-based imaging to diagnose grapevine diseases. Although smoke pollution from forest fires prevented drone flights for most of the 2021 growing season, flights were conducted in September to meet most objectives. The flights combined multispectral and thermal imaging (co-mounted imagers). The imaging was conducted in collaborative studies with JR Urbez Torres.  An analysis procedure was developed using point cloud imagery to determine reflectance and emission at different heights of the foliage canopy.  This image analysis work is in being conducted by Brad Estergaard and will continue in 2022-2023, under Dr. Ben-Min Cheng. The original PI for this project, Dr. Pat Bowen, retired in September, 2021.

- Pat Bowen, AAFC Summerland

Thank you to our funding Partners:


Agriculture & Agri-Food Canada through the Canadian Agricultural Partnership


British Columbia Wine and Grape Council, Grape Growers of Ontario, Ontario Grape and Wine Research Inc., Conseil 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 final year of the program. For more information, please contact us

From Our Team

  • CGCN certification will make a long-term contribution to the continuous pursuit of excellence of the Canadian wine sector by ensuring that the best quality, disease free propagating material is available to the grape industry.
    Hans Buchler, Chair of CGCN
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