Patricia A. Skinkis

Influence of cluster zone leaf removal on Pinot noir grape chemical and volatile composition

The influence of cluster-zone leaf removal on Pinot noir vine growth and fruit chemical and volatile composition was investigated in 3 years. Different severities of leaf removal (0%, 50%, 100%) were imposed during the pea-size stage of development from the cluster zone. Results show that cluster-zone leaf removal had little influence on vine growth, crop load, or grape maturity in terms of total soluble solids (TSS), pH or titratable acidity (TA) at harvest. However, 100% leaf removal resulted in higher concentrations of quercetin glycoside in grapes compared to 0% leaf removal. The 100% leaf removal also increased concentrations of petunidin- and malvidin-3-monoglucoside anthocyanins in two out of 3 years (2010 and 2012) by an average of 62% and 53%, respectively. In addition, 100% leaf removal resulted in higher concentrations of β-damascenone, and some bound-form terpenoids. The increases in β-damascenone were positively correlated to the increased sunlight exposure.

Relationship between rust mites Calepitrimerus vitis (Nalepa), bud mites Colomerus vitis (Pagenstecher) (Acari: Eriophyidae) and short shootsyndrome in Oregon vineyards

Abstract Short Shoot Syndrome (SSS) causes severe crop losses in Oregon vineyards due to bunch necrosis during the early part of the season. Other symptoms include malformed leaves, unusually short and angled shoots, scar tissue and bronzed leaves close to harvest time. This work shows that SSS found in Oregon vineyards is closely associated with grape leaf rust mite, Calepitrimerus vitis (Nalepa) infestations. Very few bud mites, Colomerus vitis (Pagenstecher), were found in the vineyards during the current year and no relationship could be found between SSS symptoms and this species. During winter, rust mites are dormant and no evidence of direct bud damage from rust mites was found inside undeveloped buds. Tissue damage from mites was first observed between bud break and the two-leaf stage in mite infested vineyards. Rust mite colonies were found under outer bud scales and bark of canes close to the buds. Crop losses as high as 23.7% were directly linked to rust mite infestations and SSS from several vineyards sampled in Oregon.

N, P, and K Supply to Pinot noir Grapevines: Impact on Vine Nutrient Status, Growth, Physiology, and Yield

Pinot noir grapevines (self-rooted Pommard clone) were grown in a pot-in-pot sand culture vineyard to examine the impact of low N, P, and K supply on vine growth and physiology. Four-year-old vines were given either full nutrition (Control) or reduced levels of each N, P, and K supplied at 50%, 20%, or 10% of the Control rate with all other nutrients held constant over three years (2006–2008). Vine growth, nutrient status, photosynthetic parameters, yield, and berry quality were monitored. The N, P, and K status of vines was reduced by each of the intended treatments, although N and P concentrations in leaf blades and petioles were reduced earlier and to a greater extent than K. Low N treatments reduced dormant season cane weights in all years, shoot lengths and leaf area in 2008, and fruit yield in 2008. Yield reduction under low N supply in 2008 was primarily a result of reduced berry size. Low N also reduced single leaf photosynthesis and quantum efficiency of photosystem II in 2008, while low P and K did not. Juice YAN (yeast assimilable nitrogen) levels were greatly reduced by low N supply in 2007 and 2008, although YAN was lower in 2007 across all treatments. Low P and low K supply did not alter growth or yield. Low P supply reduced juice P concentrations, but low K supply did not alter juice K. Reduced yield, growth, and juice YAN levels in low N treatments provide a framework to refine leaf blade and petiole N standards for Pinot noir grown in the region, but limiting levels of P and K were not as clearly defined.

Pinot noir wine volatile and anthocyanin composition under different levels of vine fruit zone leaf removal.

The impacts of fruit zone leaf removal on volatile and anthocyanin compositions of Pinot noir wine were investigated over two growing seasons. Wine volatiles were analyzed by multiple techniques, including headspace solid phase microextraction-GC-MS (HS-SPME-GC-MS), headspace-GC-FID (HS-GC-FID) and stir bar sorptive extraction-GC-MS (SBSE-GC-MS). Fruit zone leaf removal affected the concentration of many grape-derived volatile compounds such as terpene alcohols and C13-norisoprenoids in wine, although the degree of impact depended on the vintage year and severity of leaf removal. Fruit zone leaf removal resulted in greater concentrations of linalool, α-terpineol and β-damascenone but had no impact on other terpene alcohols or β-ionone. Fruit zone leaf removal had no consistent impact on C6 alcohols, volatile phenols, lactones, fermentation-derived alcohols, acids, or most esters. Fruit zone leaf removal increased anthocyanins in final wine.

Developmental Parameters and Seasonal Phenology of Calepitrimerus vitis (Acari: Eriophyidae) in Wine Grapes of Western Oregon

ABSTRACT Developmental parameters of protogyne Calepitrimerus vitis (Nalepa) (Acari: Eriophyidae) were determined at 12, 15, 17, 22, 25, 28, 31, and 34°C to better understand seasonal activity, population growth, and ultimately more effectively manage pest mites in wine grapes. Net reproductive rate (Ro) was greater than zero at all temperatures with the maximum Ro (9.72) at 25°C. The lowest estimated Ro (0.001) occurred at 34°C. There was a gradual decrease in mean generation time (T) as temperatures increased from 17 to 31°C. The shortest and longest generation time was recorded at 31°C (T = 5.5 d) and 17°C (T = 17.5 d). Rates of natural increase were lowest at 17°C (0.035) and increased with increasing temperatures, respectively. The peak rate of natural increase value (0.141) was at 25°C. Estimations for minimum and maximum developmental thresholds were 10.51 and 39.19°C, respectively, while the optimum developmental temperature was 26.9°C. The thermal constant for egg to adult development was estimated at 87.7DD. The highest fecundity was observed at 25°C. These parameters indicated that mites begin feeding at the onset of shoot growth when tissue is most susceptible in spring. Historical weather data showed that vines are in this susceptible growth stage for longer periods in the cool Willamette Valley compared with warmer Umpqua and Applegate/ Rogue Valley regions. Estimation of degree-days indicated when deutogyne mites move to overwintering refuge sites. Degree-day accumulations indicated up to 14 generations per growing season.

Nitrogen Requirements of Pinot noir Based on Growth Parameters, Must Composition, and Fermentation Behavior

A study to reassess the nitrogen (N) requirements for Pinot noir was carried out using a pot-in-pot vineyard where N inputs were carefully controlled. Pinot noir grafted on 101-14 rootstock was exposed to five levels of N supply beginning in their fourth growing season, and vine productivity, berry chemistry, and must fermentation dynamics were studied over three years. N supply altered the N status of vines in accordance with expectations. Varying N had a greater impact on vegetative growth parameters than upon reproductive responses. For example, at veraison, leaf area of vines exposed to the three lowest rates of N was reduced in all years, but yield was only reduced at the lowest N rate in the first year and at the two lowest N rates in subsequent years. Fruitfulness and fruit set were reduced slightly by low N, while flower number of inflorescences was unaffected. Effects on berry maturity indices at harvest were generally small, but effects on must yeast assimilable nitrogen (YAN) concentrations were large. YAN was reduced from ~200 mg N/L in the Control to as low as 25 mg N/L at the lowest N rate after three years. Treatments with lower YAN required more time to complete alcoholic fermentation, particularly those with YAN below 100 mg N/L. However, all musts fermented to dryness. Reducing vegetative growth of Pinot noir can be achieved prior to reducing yield by reducing N status when vines are cropped at levels typical for premium wine production in the region. YAN levels as low as 100 mg N/L may be a better production target for wineries to achieve minimum fermentation requirements of Pinot noir.

Spur Pruning May Be a Viable Option for Oregon Pinot noir Producers Despite Industry Fears of Lower Productivity

Summary Goals: Winegrape production is more costly in Oregon than in other US growing regions, and industry faces rising production costs and labor concerns. Growers are considering ways to reduce labor and introduce mechanization. Spur pruning requires less labor and is more readily mechanized than cane pruning; however, the majority of Oregon growers use cane pruning. We conducted industry surveys and interviews to understand why cane pruning is preferred and determine potential barriers to adopting spur pruning. We conducted a vineyard case study to quantify fruitfulness and yield of cane- and spur-pruned vines to determine the potential for spur pruning in Pinot noir. Key Findings: The majority of survey respondents (76%) primarily used cane pruning on cool climate cultivars because they believe that spur pruning reduces yields and fruit quality and increases fungal and mite pests. A total of 35% believed that spur pruning reduces yield due to vines having unfruitful basal buds. Interviews of Pinot noir growers who use both spur and cane pruning revealed that spur pruning could achieve desired yields, while reducing production costs and labor dependency. Their observations did not support survey respondent concerns about severely reduced yields, fruit quality, and increased mites or diseases. The Pinot noir vineyard case study revealed that cane and spur pruning led to similar yields, cluster size, and fruit ripeness. Data from spur-pruned Pinot noir vines showed that shoots arising from basal, first, and second buds were fruitful. Impact and Significance: Industry perception and lack of experience with spur pruning is preventing adoption. Expectation of low yields is based on industry hearsay, not direct experience. Concerns that spur pruning lowers quality may be derived from mechanization research from regions that focus on quantity, not quality. However, grower interviews and field data show that Pinot noir is fruitful at basal nodes and can be spur pruned without limiting yield or quality based on Oregon standards. Converting to spur pruning reduced pruning cost, and research/demonstration projects are needed to help small, quality-focused industries make necessary adaptations to their production systems.