Avoid mixing biologicals with antimicrobials

Dr. Jay W. Pscheidt and Lisa Jones, Dept. of Botany and Plant Pathology, Oregon State University

Actinovate AG (Streptomyces lydicus WYEC 108) and many other biological products are used in the management of organic grapes. Tank mixing more than one product is both economical and time-saving but tank mix compatibilities with biological control products such as Actinovate have not been thoroughly evaluated. In 2016, we examined the tank mix compatibility of Actinovate AG with commonly used organic products.

Actinovate AG was prepared at a concentration of 0.1g/ml. A 300 ml solution of Actinovate was prepared in a 500 ml beaker then mixed with each material and allowed to stand for 30 minutes. The mixture was then plated onto agar and incubated for 7 days at room temperature. The number of colony-forming units (CFU) of S. lydicus exposed in each mix was assessed daily and compared to an Actinovate plus water only control. The percentage of S. lydicus CFU in each tank mix compared to the CFU in the Actinovate control was calculated.

An average of 3.2×105 S. lydicus CFU developed after 7 days incubation on the various media when Actinovate was just mixed with water. Several products inhibited the growth of S. lydicus when prepared in as a mixture in the laboratory. No growth of S. lydicus was observed on plates when Actinovate was mixed with Horticultural Vinegar, a high rate of Regalia, Rex Lime Sulfur, Serenade Optimum, or Solubor DF. Less than 10% of the S. lydicus CFU grew when Actinovate was mixed with Biomin Calcium, Botector, Neptune’s Harvest 2-4-1 fish fertilizer, or Thuricide. Significantly fewer S. lydicus CFU grew when Double Nickel, the low rate of Regalia, Serenade Max, the high rate of Stimplex or Toggle were mix with Actinovate. There was no significant difference in the number of S. lydicus CFU that grew when Zen-O-Spore was mixed with Actinovate. The number of S. lydicus CFU was greater than double (219%) or quadruple (482%) that of the Actinovate control when mixed with Nitrozyme or the low rate of Stimplex, respectively.

Many of the biological products in this study grew quicker than S. lydicus under laboratory conditions. These fungi or bacteria generally outcompeted S. lydicus for space and resources on the agar plates. The fungus found in Zen-O-Spore was slower to grow and did not outcompete S. lydicus during the 7-day incubation.

This data does not imply a lack of or enhanced disease control in the field. For example, blueberry field trials over a 2-year period where Actinovate was mixed with Simplex did not result in disease control that was different than when either product was used alone. The data does indicate incompatibility between various products used in organic production.

For a complete data set please visit: http://sites.science.oregonstate.edu/bpp/Plant_Clinic/Fungicidebooklet/2016/Blueberry3.pdf

Pest Alert: Grape Cane Borer

Dr. Patty Skinkis, Professor and Viticulture Extension Specialist, OSU
Dr. Vaughn Walton, Professor and Horticultural Entomologist, OSU

There have been an increasing number of reports of grape cane borer presence and damage in vineyards throughout the Willamette Valley this winter. Typically these reports during the bud break period in April when adults are active and evidence of shoot dieback occurs. However, we have received numerous reports this January and early February as growers begin pruning. This observation may be due to various factors including more suitable weather conditions (winter and summer), higher levels of populations surviving, more suitable host plant materials, increased awareness and improved monitoring. The borers can have a long life cycle within the vine, living as larvae (grubs) within the shoot or cane for nearly one year. Adults lay eggs during early spring and hatch and develop into larvae that feed on the shoot tissues during the growing season. They remain in the wood as pupae during winter and may be found when pruning commences. Both pupae and adults have been reported in southern and mid-Willamette Valley vineyards this winter. This article covers the most salient points for your awareness this winter; please consult additional resources below for further details.

What to look for in the vineyard:
Galleries burrowed by larvae can be observed in cane tissue usually in older or dead wood, canes, spurs, or cordons. These holes are round, drill-like holes of ~0.4 mm diameter, and they are often accompanied with sawdust that was produced by the adult when burrowing into the shoot during late summer or early fall the year prior. Cutting into the wood near these holes during pruning will likely reveal a pupa that is 1-8 mm in length (<0.3 in).

Management:
Insecticide application is often difficult to apply during the dormancy period due to the difficulty for the application to reach the pest and the inability to get into the vineyard with equipment. There are biological controls, such as the Steinernema carpocapsae, an entomopathogenic nematode, that may be used, but care needs to be taken to ensure that the product is handled properly and applied to the entry points of the pest to be effective. In some cases, the best method will be to cut out any canes that have the burrow holes evident. Remove pruning wood, as the wood contains the pupae that will emerge in spring. Removing the pest from the vineyard will ensure that a population does not exist to allow new infestations into tissues.

For more information about the cane borer, please see the following resources:

Vole Damage in Vineyards

Dr. Patty Skinkis, Associate Professor and Viticulture Extension Specialist, OSU 

I received a number of reports of vole damage in vineyards throughout the Willamette Valley this season. Evidence of their presence became visible in August with feeding damage to trunks (Figure 1) and within the canopy, including damage to shoots and rachises of grape clusters (Figure 2). Voles eat vegetation and typically feed on roots or the base of trunks. Voles do not typically cause issues until a population peak and/or environmental conditions allow for habitation. They may reach epidemic-level populations every ten to 12 years, but these population surges are not predictable and last for one year (Gunn et al. 2011). The Willamette Valley’s last reported vineyard infestation occurred in 2005, and some vineyards lost vines due to the damage.

Preventing and eradicating voles.  Our best suggestions to growers who have been observing vole presence in vineyards has been to encourage eradication. Trapping or baiting voles may not be practical on large acreage or advised with certain farming certifications. For example, zinc phosphide is not allowed in organic production. However, soil tillage or mowing may provide some level of prevention and control. Research in field crops show that tilling the soil is the most effective method of reducing vole populations (Jacob 2003), by disturbing their burrows and causing movement to other vegetated areas. Voles avoid bare ground, so tillage can prevent habitation altogether. In the Jacob (2003) study, they found voles disappeared altogether after disking to a depth of 19 inches. Mowing vegetation was found less effective than tillage, as the mulch from mowing allowed sufficient cover for the voles and did not encourage movement away from the cropped areas. Avoiding mulch layers or vegetation growth under-vine will prevent voles from inhabiting the areas near grapevine trunks and feeding on roots and trunks when food sources are limited.

Scouting for damage. Voles tend to feed on vine roots and at the base of trunks. Look for feeding damage at and just below the soil surface. Since the feeding typically occurs through the phloem and vascular cambium, the cell layers that lie between the phloem to the exterior and xylem to the interior, the vascular system is compromised. As a result, affected vines may turn color abruptly (yellow or red, Figure 3), as they have limited ability to move photosynthates (sugars) and mineral nutrients through the vines to the roots once the phloem and cambium are damaged. Roots are actively acquiring carbohydrates and mineral nutrients from the canopy during late season in preparation for the next year. Having this connection severed is a major issue.

Can anything be done to repair damaged vines? Vines with girdled trunks and root damage may not survive if the damage is done to the circumference of the vine. This is due to the lack of vascular cambium to grow new phloem tissue and “heal” the wound. The best thing to do at this time is flag vines with damage now and check back later in winter during pruning and early spring. If damage was only apparent in the canopy (rachises, berries, and shoots), vines may be able to be pruned to healthy tissue in winter. However, also be sure to flag these vines for follow-up.

Because voles do not hibernate, high populations this winter may pose a threat to vines if they continue feeding in areas where they were observed this season. It will be important to remove vegetation by way of tilling soil or removing mulch layers or vegetation under-vine to avoid any further damage.

Literature Cited

Gunn D, Hirnyck R, Shewmaker G, Takatori S, and Ellis L. 2011. Meadow voles and pocket gophers: Management in lawns, gardens, and cropland. University of Idaho, PNW 627.

Jacob J. 2003. Short-term effects of farming practices on populations of common voles. Ag Ecosyst Environ 95:321-325.

 

Figure 1. Vole damage to the base of a trunk on a mature grapevine. Photo courtesy of Ryan Wilkinson.

 

Figure 2. Feeding damage is apparent on the top of the grape cluster’s rachis (peduncle) and the lower portions of the shoot from which it originates. Photo courtesy of Ryan Wilkinson.

 

Figure 3. Vines with vole damage to the trunk show almost complete reddening of the canopy in Pinot noir vines. Photo courtesy of Ryan Wilkinson.

 

Rust Mites Can Cause Damage Shortly After Budbreak

Rust Mites Can Cause Damage Shortly After Budbreak

Dr. Patty Skinkis, Viticulture Extension Specialist & Associate Professor

Grape rust mites have been a nuisance pest in vineyards of western Oregon for years. They can be found living on grape tissues from early spring through summer. Grape rust mite has been known to cause shoot deformity early in the growing season with most notable damage in years when vines have delayed growth under cool conditions.

Being aware of the first signs and symptoms of rust mite infestation in early spring is important to determine if there is a problem. However, visual symptoms are not enough for action. It is critical to determine presence of grape rust mites before considering application of miticide sprays. The presence of high numbers of rust mites have been found to cause severe stunting of emerging buds and  young shoots. For examples of these symptoms, see the grape rust mite section of the PNW Insect Management Handbook. There can be numerous other causes of stunted shoots, but with the hype of rust mite concerns, many growers blamed rust mites as the cause of all stunted shoots. As a result, there have been potentially unnecessary applications of miticides (sulfur, lime sulfur, stylet oil, or other miticide products) early in the season.

Grape rust mites are impossible to see with the naked eye, so tissue collection and viewing under magnification is required. A user-friendly method was recently developed by a team at the OWRI to monitor grape rust mites on vine tissues. This method has since been employed by growers in Oregon to determine presence of rust mites. The protocol is available for use and links provided below:

Using this method, we were able to determine a strong correlation of rust mite presence on stunted shoots early in the season. Damaged shoots often had hundreds of mites; there were over 100 mites found on shoots <10 cm in length using the rinse in bag protocol and up to 500 mites when evaluated upon subsequent extractions (Schreiner et al. 2014). Since there can be great variability in mite numbers and rapid growth of tissues early season, it is difficult to determine clear action thresholds. However, action is warranted if there is significant shoot stunting, deformity and confirmed high populations of rust mites. In-season sulfur sprays that are applied as a means to prevent powdery mildew has been found to keep rust mite populations in check (Schreiner et al. 2014). Current recommendations exist for early season rust mite control, and those can be found in the 2015 Pest Management Guide for Wine Grapes in Oregon.

For more information about monitoring for rust mites and management, see the following publications and resources:

Schreiner, R.P., P.A. Skinkis, and A.J. Dreves. 2014. A rapid method to assess grape rust mites on leaves and observations from case studies in Western Oregon vineyards. HortTechnology. 24: 38-47.

Skinkis, P.A., J.W. Pscheidt, E. Peachey, A.J. Dreves, V.M. Walton, I. Zasada, R. Martin, D. Sanchez, and C. Kaiser. 2015. 2015 Pest Management Guide for Wine Grapes in Oregon. OSU Extension Publishing.  https://catalog.extension.oregonstate.edu/sites/catalog.extension.oregonstate.edu/files/project/pdf/em8413_0.pdf

Skinkis, P. 2014. Grape Rust Mites, eXtension/eViticulture.org. http://www.extension.org/pages/33107/grape-rust-mite#.U_yZCHcXOVo

Skinkis, P., J. DeFrancesco, and V. Walton. 2015. Grape Rust Mite, PNW Insect Management Handbook. http://insect.pnwhandbooks.org/small-fruit/grape/grape-grape-rust-mite

September 21-27 is Farm Safety Week

Did you know that September 21-27 is National Farm Safety Week? It’s a good time to put on your learning cap and brush up on safety practices that will keep you and your employees safe. In honor of National Farm Safety Week, the Department of Environmental & Occupational Health Sciences -Pacific Northwest Agricultural Safety & Health, is providing information from the Northwest and other NIOSH Regional Ag Centers. For more information, search online for #NFSW14. 

 

Farmsafety

 

 

Seven Questions with…

Oregon State University Extension and Experiment Station Communications

  Vinay Pagay

1. What is your position at SOREC/OWRI?
I started my job at OSU-SOREC and the OWRI in January 2014 after receiving my doctorate at Cornell University in Ithaca, NY. My position is a combination of viticulture research (60%) and extension (40%), so an interesting mix of basic and applied research, as well as addressing issues faced by the grape and wine industry in Southern Oregon. In my position, I cover the Southern Oregon AVA (American Viticultural Area), which includes the Rogue (Bear Creek and Applegate Valleys), Illinois, and Umpqua Valleys.

2. What do you enjoy most about your work?
The most interesting part about this job is the diversity of viticulture that exists in Southern Oregon. Sub-regional climates, soils, and topography contribute to this diversity, but the plethora of grape varieties – by some accounts up to 70! – from both warm and cool climates make my job not only interesting but also challenging. Can you tell the two Portuguese cultivars Tinta Amarella (Trincadeira, if you prefer) and Tinta Barocca apart by looking at just their leaves? Email me if you’re curious to know how!

3. When you’re not working, what do you do?
My time outside of the office or vineyard is spent working out (I compete in Olympic-distance triathlons, so a lot of swimming/biking/running/weight training), hiking the hills around Southern Oregon, playing golf, and reading (currently a book entitled ‘The Sleepwalkers’ by Christopher Clark, a Cambridge historian; it is about the events leading up to the first world war – quite a gripping story). I am trying to get back into playing competitive tennis and classical piano, but have yet to find time for these. I also enjoy home brewing and baking breads when I’m home over the weekends.

4. How did you choose your career path?
While pursuing my first degree in computer engineering, I had an old friend from high school visit me in Montreal who led me through my first structured tasting of wine (red was the color of the evening). This delightful experience led me to read and learn more about the world’s wine regions, styles, and wine production, culminating in my enrolling at Brock University in Canada to do a degree in enology and viticulture. The mentorship I received while at Brock, and later at Cornell, were instrumental in my decision to pursue this career and current job at OSU/OWRI.

5. What’s the best advice you’ve ever received?
Take up a job you love and you’ll be successful (and maybe even wealthy!) before you know it. I think at least part of it has come true already!

6. Which three people (living or dead) would you invite to dinner?
-Thomas Jefferson (for his wine collection, of course)
– Sergei Prokofiev (Russian composer)
– Bill Clinton

7. What is your vision for the Southern Oregon wine industry?
I see the wine industry in Southern Oregon as destined for greatness and popularity not only within Oregon but also across the country. With significant acreages being planted with winegrapes across the region, higher grape and wine quality from the greater experience of the industry, the profile and visibility of this region is steadily increasing. The diversity of available grape varieties and wine styles provide tremendous opportunities for this region. While Southern Oregon has a number of major tourist attractions, e.g. Crater Lake, the Britt and Oregon Shakespeare Festivals, I envision wine tourism growing in this small but dynamic region of Oregon.

Oregon Department of Agriculture Grape Quarantine Update

Oregon Department of Agriculture Grape Quarantine Update 

glassy-winged-sharpshooter

The Oregon Department of Agriculture (ODA) has updated its grape quarantine rules and added Pierce’s Disease (Xylella fastidiosa) to the already listed Grapevine fanleaf virus, grapevine leafroll associated viruses, grapevine corky bark disease agent, grape phylloxera, vine mealybug, and  European grapevine moth. The quarantine places restrictions on the importation of all parts of the grapevine into Oregon including the harvested fruit.  Please review the accompanying quarantine of Glassy-Wigned Sharpshooter as it is a vector of Pierce’s disease.

Please take the time to review these important changes. To view them in more detail, please visit the ODA website at: http://www.oregon.gov/oda/Pages/default.aspx.

Link to Grape Quarantine: 603-052-0051_072462014CLEAN

Link to Glassy-Wigned Sharpshooter: 603-052-1221_07242014CLEAN

 

Monitoring Vineyards for Grape Rust Mites in Late Summer

Rust mites can be a nuisance pest and require careful monitoring and assessment.  Check out the post below written by Dr. Patty Skinkis, Viticulture Extension Specialist & Associate Professor, which provides information on how to deal with these pests.

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Monitoring Vineyards for Grape Rust Mites in Late Summer

Stunted_shoot_rust_mite

Dr. Patty Skinkis, Viticulture Extension Specialist & Associate Professor

Grape rust mites have been a nuisance pest in vineyards of western Oregon for years. They can be found living on grape tissues from early spring through summer. During late summer and into fall, they retreat to overwintering sites in the bark and bud scales. The grape rust mite has been known to cause shoot deformity early in the growing season and stippling of leaves as they advance into the upper canopy in summer. If populations are very high (hundreds to thousands per fully expanded leaf), the leaf tissue can begin to discolor, starting to turn a dark green, then purplish and finally a bronzed color in late summer to early fall. This discoloration can lead to reduced photosynthetic ability of the vines if a large percentage of the vine’s leaf area is damaged.

Monitoring for signs and symptoms of rust mite infestation are important to do throughout the season. However, determining the presence of grape rust mites in your vineyard now (late August and early September) will help determine whether control methods are warranted the following season. We developed a user-friendly method by which to monitor grape rust mites on vine tissues, and this method has since been employed by growers in Oregon to determine presence of rust mites. The protocol for this method is available for use:

  • Grape tissue washing protocol (link to document)
  • Visual work flow of protocol (link to document)

Using this method, we were able to determine a strong correlation of stippling symptoms to rust mite presence on small shoots and leaves. The greater the stippling severity on the leaf, the greater the number of rust mites. The bronzing of leaves was also associated with high rust mite numbers, but the symptom was associated with feeding later in the summer on older leaf tissues. Now is your last chance to monitor your vineyards for these symptoms and verifying mite presence before the hustle of harvest. For examples of these symptoms, see the grape rust mite section of the PNW Insect Management Handbook.

If you find significant rust mite damage and presence, it is best to make note of those vineyard blocks that are most damaged and consider your management options for the future. In some cases, you may want to reevaluate your in-season fungicide program, as sulfur has been found to be effective at reducing or maintaining low rust mite populations. Also, it is best to know the infestation status of your vineyard now so that plans can be made to monitor and take action against rust mites shortly after bud break the following spring. Current recommendations exist for early season rust mite control, and those can be found in the pest management guide released by OSU Extension each spring.

For more information about monitoring for rust mites and management, see the following publications and resources:

Schreiner, R.P., P.A. Skinkis, and A.J. Dreves. 2014. A rapid method to assess grape rust mites on leaves and observations from case studies in Western Oregon vineyards. HortTechnology. 24: 38-47.

Skinkis, P.A., J.W. Pscheidt, E. Peachey, A. Dreves, V.M. Walton, D. Sanchez, I. Zasada, and B. Martin. 2014. 2014 Pest Management Guide for Wine Grapes in Oregon. OSU Extension Publishing. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/45975/em8413.pdf

Skinkis, P. 2014. Grape Rust Mites, eXtension/eViticulture.org. http://www.extension.org/pages/33107/grape-rust-mite#.U_yZCHcXOVo

Skinkis, P., J. DeFrancesco, and V. Walton. 2014. Grape Rust Mite, PNW Insect Management Handbook. http://insect.pnwhandbooks.org/small-fruit/grape/grape-grape-rust-mite

Merlot variability at harvest affects wine composition

Amanda Vondras, Ph.D  Student
Dr. Elizabeth Tomasino, Assistant Professor
Dr. Laurent Deluc, Assistant Professor

The grapevine has a certain capacity to buffer itself in a changing environment without disrupting normal developmental processes. How different cultivars of Vitis vinifera respond to changing environmental conditions and viticultural practices beyond their buffering capacity are interesting research questions. It is complicated to consider these effects during a multi-dimensional developmental process like ripening. One approach to describe grape berry ripening is to treat whole clusters as a unit, aggregating all the berries within a cluster together for measurements, resulting in data that represents the average contribution of genes or metabolites during berry ripening. This approach overlooks dimensions of the ripening process at the berry level.

Research that we have conducted in the Deluc Lab found different ripening rates of berries within the same cluster. There is inherent variability within the cluster, the vine, and between vines. However, this is reduced as berries approach maturity in some cultivars. In examining how vineyard practices and changing environments affect fruit composition, we may be able to consider ripening within the cluster and the potential impact on ripening uniformity toward harvest, which we believe to be an indicator of increased quality. Within the Deluc Lab, we are researching the variability of individual berries during ripening to determine if this provides a more accurate depiction of the ripening process. We are collaborating with Drs. James Osborne and Elizabeth Tomasino to further study the effects that persistent berry variability has on fruit and wine composition and perceived wine quality.

During mid-véraison, there is significant variability of the berries within the cluster. Berries differ in size, softness, sugar content, and color. As grapes develop color near harvest, it may appear that variability is reduced. It is not clear whether or not variability is gone by harvest as this has not been researched extensively. A study conducted by Long (1987) revealed that the quality and complexity of a wine was dependent upon the average berry composition. Cluster heterogeneity at maturity was found to increase green characteristics from less ripe berries or jam-like characteristics from over-mature berries in wines produced. Likewise, this diversity of ripening states of berries within a cluster influenced phenolic maturity and wine composition at commercial harvest (Kontoudakis et al. 2012). In theory, we believe uniform cluster composition to be desirable for winemaking (Keller 2010). However, few studies have defined metrics for a “uniform” cluster. This is no simple task given that there are thousands of metabolites that comprise a grape berry and potentially contribute to fruit and wine quality.

The Deluc and Tomasino Labs conducted a research project in 2012 at OSU’s Woodhall Vineyard to estimate the influence of berry variability on Merlot wine composition. At mid-véraison, 100 clusters were used to monitor the progression of berries that were either green or red at that time point. The pedicels of these two berry classes were tagged with paint. Each cluster was harvested six weeks after mid-véraison, and berries were sorted based on the initial tagging as the green or red groups. Non-tagged berries that represented the intermediate ripening stages between green and red berries were used as the control group. Each group of berries was fermented separately using micro-ferments.

Chemical analysis of wine esters showed significant differences between the red and green berry groups as well as differences to the control. The wine made from the green group contained lower concentrations of some esters, and wine made from the red group contained higher concentrations of different esters. Differences in esters correspond to red- and black-berry aromas in Merlot (Pineau et al. 2009). Wine sensory analysis also resulted in significant differences with control wines having more intense floral, jam, and spice aromas, and greater in-mouth fruit density. Wines from the green berry class had more intense herbal and green aromas, and wines of the red berry class had more intense dark fruit, red fruit, and spice aromas. When wines were assessed for quality using a scale of 1 (low) to 3 (high), control and green berry wine were ranked as higher quality than the red berry wine. We concluded that berry variability present in Merlot at harvest affects the sensory characteristics and chemical composition of the wine. Further experiments to quantify non-volatile compounds (anthocyanins, tannins, and other phenolic compounds) will be performed on these wines using the OSU Mass Spectrometry Facility to complement our sensory and volatile chemical data.

To better understand the mechanisms of grape ripening, we are faced with a myriad of questions about the source, regulation, and mediation of asynchronous ripening. Although we assume that homogeneity of berries is best and that a heterogeneous crop (more variably ripe berries) would result in poorer wines, the interpretation of what level of variability is acceptable for optimum wine quality is unknown. There are many avenues to pursue in this research, as cultural practices and environmental factors may exacerbate or reduce the amount of variability during berry development. Furthermore, the amount of berry variability within the cluster at harvest may differ among cultivars.

Literature Cited

Keller, M. 2010. Managing grapevines to optimize fruit development in a challenging environment: A climate change primer for viticulturists. Aust. J. Grape Wine Res. 16:56-69.

Kontoudakis, N., M. Esteruelas, F. Fort, J.M. Canals, V. De Freitas, and F. Zamora. 2011. Influence of the heterogeneity of grape phenolic maturity on wine composition and quality. Food Chem. 124:767-774.

Long, Z.R. 1987. Manipulation of grape flavour in the vineyard: California, North Coast region. In Proceedings of the Sixth Australian Wine Industry Technical Conference, Adelaide, July 1986. T.H. Lee (ed.), pp. 82-88. Australian Industrial Publishers, Adelaide.

Pineau, B., J.C. Barbe, C.V. Leeuwen, and D. Dubourdiea. 2009. Examples of perceptive interactions involved in specific “Red-” and “Black-berry”aromas in red wines. J. Agric. Food. Chem. 57:3702-3708.

Selvaraj, Y., D.K. Pal, R. Singh, and T.K. Roy. 1995. Biochemistry of uneven ripening in Gulabi grape. J. Food Biochem. 18:325-340.

 

Ripening synchronization research conducted to understand berry uniformity at harvest

Dr. Laurent Deluc, Assistant Professor
Dr. Satyanaryana Gouthu, Postdoctoral Research Associate

Grape berry development involves natural biological programs that occur in succession during the growing season. These biological programs are what direct cell division, growth, and fruit ripening. Environmental factors such as light, temperature, water, and nutrient status of the vine affect the development of berries in this process. Within the grapevine, many hormones interact in response to environmental stimuli and coordinate the processes of fruit ripening. However, all berries within a cluster do not go through the ripening process at the same rate. At any given time, some berries will be more developed than others. This phenomenon of uneven ripening is called “asynchrony,” and the variability among berries is most noticeable during mid-véraison.

To understand this phenomenon of asynchrony, we conducted research in Pinot Noir across four years (2010 to 2013). Berries were classified into four groups based on their level of development at mid-véraison as measured by color and softness. These classes include green-hard, green-soft, pink-soft, and red-soft. These berries were at different ripeness states and represented the transition of berries during véraison. Those green berries that were lagging behind in development had transitioned through pink and then red stages at a later time.

To determine ripening development, we monitored individual berries as they advanced from the various stages to the red-soft stage on intervals of 6, 10, and 13 days for pink-soft, green-soft, and green-hard berry classes, respectively. We found that once the lagging berry classes reach their corresponding red-soft stage, they develop at a faster rate during the two weeks following mid-véraison than their riper counterparts. This enhancement in the ripening rate of lagging berries resulted in reduced variability within a cluster at harvest with respect to sugar and pigments (color). This mechanism is known as “ripening synchronicity,” and it involves changes in gene expression and hormones involved in ripening, suggesting that a coordinated mechanism of control is occurring at the genetic level (Gouthu et al., in progress).

Vineyard management practices such as cluster-zone leaf removal, cluster thinning, and deficit irrigation have been used for decades to improve fruit quality and achieve more uniform ripening. Several genomic studies focused on understanding the changes in gene expression of berries within a cluster due to selective defoliation (Pastore et al. 2013), cluster thinning (Pastore et al. 2011) and water deficit (Deluc et al. 2009). However, no study has investigated the naturally occurring changes in gene expression associated with the reduction of uneven ripening without modifying viticulture practices in the vineyard. We believe that uniform ripening is potentially important for grape growers and winemakers, and understanding the plasticity of grape berry ripening could be beneficial in adapting cultivars to a specific growing region, vineyard management practice, or wine style. From an ecological point of view, the grapevine benefits from having a more coordinated ripening of the berries to entice birds and other animals to feed and disperse seeds. As a result, cool climate cultivars may have adapted to complete this process more quickly to survive. Short growing seasons and advanced phenological stages have been reported in several regions across the world (Fraga et al., 2013). The ability to ripen more quickly is an interesting genetic trait to research as we seek better methods for grape production and face climate change.

Identifying developmental and environmental factors that control synchronized ripening through genomic research will increase our knowledge of ripening processes within grape berries. This information may allow us to combine applied and basic research methods to determine if there are viticulture practices that can be used to improve cluster ripening uniformity and wine quality. For example, since we know hormones play a critical role in the ripening process, we may be able to conduct more detailed research on the use of plant hormone sprays during véraison to achieve more uniform berry composition at harvest. Also, we can study the genomic and physiological response of berry ripening synchronicity with traditional vineyard management practices (canopy management, regulated deficit irrigation, and fertilization). These types of partnered applied and basic studies have not been conducted to date. Future short-term research projects to be conducted at OSU will focus on determining specific contributions of ripening-related hormones in the control of this mechanism. We hope to determine field applications that prevent or eliminate uneven ripening in the vineyards. Basic research will focus on the identification of the genes responsible for this regulatory mechanism within such applied projects. Finally, these findings may be helpful in developing large-scale genetic studies to determine the genetic makeup of cultivars such as Merlot, Cabernet Sauvignon, and Zinfandel that exhibit persisting levels of ripeness heterogeneity at harvest.

Literature Cited

Pastore, C., S., Zenoni, GB., Tornielli, G., Allegro, S., Dal Santo, G. Valentini, C., Intrieri, M., Pezzotti, and I. Filipetti. 2011. Increasing the source/sink ratio in Vitis vinifera (cv Sangiovese) induces extensive transcriptome reprogramming and modifies berry ripening. BMC Genomics 12:631

Pastore, C., S., Zenoni, M., Fasoli, M., Pezzotti, GB., Tornielli, and I., Filipetti. 2013. Selective defoliation affects plant growth, fruit transcriptional ripening program and flavonoid metabolism in grapevine. BMC Plant Biology 13:30

Deluc, L.G., D.R. Quilici, A. Decendit, J. Grimplet, M.D. Wheatley, K.A. Schlauch, J.M. Mérillon , J.C. Cushman, and G.R. Cramer. 2009. Water deficit alters differentially metabolic pathways affecting important flavor and quality traits in grape berries of Cabernet Sauvignon and Chardonnay. BMC Genomics 10: 212.

Fraga, H., A.C. Malheiro, J. Moutinho-Pereira, and J.A. Santos. 2013. An overview of climate change impacts on European viticulture. Food Energy Secur. 1: 94-110.