Gregory M. Peck

Characterization of the polyphenol composition of 20 cultivars of cider, processing, and dessert apples (Malus × domestica Borkh.) grown in Virginia.

Polyphenols and maturity parameters were determined in 20 apple cultivars with potential for hard cider production grown in Virginia, U.S.A. Concentrations of five classes of polyphenols were significantly different across cultivar for both peel and flesh. Total polyphenol concentration ranged from 0.9 μg/g wwb in flesh of Newtown Pippin to 453 μg/g wwb in peel of Red Delicious. Harrison, Granny Smith, Rome, Winesap, and Black Twig cultivars contained the highest concentration of total flavan-3-ols in flesh, indicating potential to impart desired astringency and bitterness to cider under processing conditions where extraction of polyphenols from peel is minimal. These results can inform selection of fruit juice, extracts, and byproducts for investigations of bioactivity and bioavailability of polyphenols, and provide baseline data for horticultural and processing research supporting the growing hard cider industry in Virginia. Based on these data, cultivars Harrison, Granny Smith, Rome, Winesap, and Black Twig show high potential for cider production in Virginia.

The interactive effect of fungicide residues and yeast assimilable nitrogen on fermentation kinetics and hydrogen sulfide production during cider fermentation

Abstract BACKGROUND Fungicide residues on fruit may adversely affect yeast during cider fermentation, leading to sluggish or stuck fermentation or the production of hydrogen sulfide (H2S), which is an undesirable aroma compound. This phenomenon has been studied in grape fermentation but not in apple fermentation. Low nitrogen availability, which is characteristic of apples, may further exacerbate the effects of fungicides on yeast during fermentation. The present study explored the effects of three fungicides: elemental sulfur (S0) (known to result in increased H2S in wine); fenbuconazole (used in orchards but not vineyards); and fludioxonil (used in post‐harvest storage of apples). RESULTS Only S0 led to increased H2S production. Fenbuconazole (≥0.2 mg L−1) resulted in a decreased fermentation rate and increased residual sugar. An interactive effect of yeast assimilable nitrogen (YAN) concentration and fenbuconazole was observed such that increasing the YAN concentration alleviated the negative effects of fenbuconazole on fermentation kinetics. CONCLUSION Cidermakers should be aware that residual fenbuconazole (as low as 0.2 mg L−1) in apple juice may lead to stuck fermentation, especially when the YAN concentration is below 250 mg L−1. These results indicate that fermentation problems attributed to low YAN may be caused or exacerbated by additional factors such as fungicide residues, which have a greater impact on fermentation performance under low YAN conditions.

Crop Load Density Affects ‘York’ Apple Juice and Hard Cider Quality

To assess the impact crop load has on hard cider chemistry, ‘York’ apple (Malus3domestica Borkh.) trees were hand thinned to three different crop loads: low [two apples per cm branch cross-sectional area (BCSA)], medium (four apples per BCSA), and high (six apples per BCSA). Higher crop loads produced smaller, less acidic fruit that were slightly more mature. In juice made from fruit from these treatments, the total polyphenol content did not differ at harvest, but, after fermentation, the medium crop load had 27% and the high crop load had 37% greater total polyphenol content than the low crop load. Yeast assimilable nitrogen (YAN) concentration in juice made from fruit from the low crop load treatment had 18% and 22% greater than the medium and high crop load, respectively. YAN concentrations in juice from the medium and high crop load treatments were similar. Our results provide apple growers and hard cider producers with a better understanding of how apple crop load impacts YAN concentrations in juice and total polyphenol concentrations in juice and cider. Hard cider is an alcoholic beverage produced from fermented apple juice or apple juice concentrate. Domestic cider consumption has increased more than 850% in the last 5 years and there are now over 550 cider producers in the United States (TTB, 2007–14; Brown, 2016). The vast majority of cider produced in the United States is made from apple cultivars that were originally planted for fresh or processing markets (Peck and Miles, 2015). Culinary apples do not have all of the fruit quality characteristics desired by cider producers, but many of the desired cider apple cultivars have not been documented as being widely planted in the United States (Miles et al., 2015; Peck, 2012; U.S. Apple Association, 2015). In the United States, where the production of traditional hard cider apple cultivars has lagged behind the increase in cider sales, methods to increase cider quality from existing apple cultivars are needed. Fruit quality attributes that are important for culinary apple production include low incidence of damage and decay, fruit shape and size (typically measured by fruit mass), peel color, flesh firmness, soluble solid concentration (SSC), titratable acidity (TA) and pH, and flavor (La Belle, 1981). Along with the starch pattern index (SPI) and internal ethylene concentration (IEC), fruit quality factors are often measured to gauge harvest maturity (Watkins, 2003). For cider production, fruit quality attributes also include polyphenol and YAN concentrations in the fruit, and juice yield, while cosmetic attributes such as color, shape, and size are much less important (Lea, 1996). Apple orchard management practices that focus on fruit quality characteristics that are desirable for cider production are needed. Specifically, most apples commercially grown in the United States have low YAN and polyphenol concentrations (Thompson-Witrick et al., 2014). While both exogenous nitrogen and polyphenols (i.e., ‘‘enological tannins’’) may be added to increase their concentration in cider, the sensory impact of addition of these products to cider warrants further investigation. For example, the addition of commercially available exogenous tannins to red wine has been shown to increase the measured total polyphenol concentration, but they did not always lead to improvement in sensory character (Harbertson et al., 2012). As such, increasing endogenous polyphenol concentration in fruit remains the generally preferred approach to achieve desired sensory characteristics for wine and cider. In European wine grape (Vitis vinifera L.) production, measurable improvements in fruit quality have been achieved through adjusting the relationship between fruit yield and vegetative growth, often referred to as crop load. Grape cluster crop load has been shown to impact secondary metabolism in grape berries, which can in turn impact wine chemistry, aroma, and flavor. For example, SSC was greater in ‘Chambourcin’ grapes that were from vines with reduced fruit clusters (Dami et al., 2006). Similarly, lower crop loads for ‘Sauvignon blanc’ grapevines resulted in wine that had more favorable sensory scores (Naor et al., 2002). A study of ‘Shiraz’ grapevines under five training systems in the Barossa Valley of Australia demonstrated that grape berry anthocyanin and polyphenol concentrations decreased with increasing crop load (Wolf et al., 2003). However, a point is reached when continuing to decrease crop load results in decreased yield and increased production cost, but no further increase in wine quality (Berkey et al., 2011; Bravdo et al., 1985; Preszler et al., 2010). Although horticultural practices for apples and grapes are quite different, wine grape growers exert a tremendous amount of effort optimizing fruit quality to make their crop more desirable to their buyers. For these reasons, crop load targets are often specified in vineyard management with the goal of maintaining optimal fruit quality for winemaking (Wolf, 2008). With the increased utilization of apples for cider production, it is necessary to more fully understand how orchard management decisions, such as crop load density, impact cider quality. The development of crop load management practices can be used by orchard managers to improve cider produced from culinary apples. The goal of this project was to assess the impact of three different crop load densities on fruit and cider quality. Materials and Methods Field treatments were conducted in a 14year-old ‘York Imperial (Ramey)’/‘M.9’ orchard at the Alson H. Smith, Jr. Agricultural Research and Extension Center (Winchester, VA) in 2014. ‘York’ apples are primarily used for processing into products such as juice, vinegar, and applesauce. On 16 June ( 50 d after full bloom), five single-tree replications of each of the three crop load treatments were implemented by hand thinning apples to the specified crop load density level on three branches per tree. The low crop load treatment was thinned to two apples per cm BCSA, the medium crop load was thinned to four apples per BCSA, and high crop load was thinned to six apples per BCSA. The rest of the tree was thinned to about the same crop load density by visually assessing the crop load on the three branches and replicating that spacing. Fruit was only sampled from the three branches that were hand thinned to the precise number of fruit per BCSA. The experiment was blocked based on a visual assessment of whole-tree crop load before the implementation of the treatments. Treatmentswere randomly assigned Received for publication 23 May 2016. Accepted for publication 18 July 2016. We thankDavid Carbaugh, AbbyKowalski, Taylor Mackintosh, Hengjian Wang, Sihui Ma, Molly Kelly, Tina Plotka, Ken Hurley, Ann Sandbrook, and Brian Wiersema for technical assistance. Funding for this work was provided by the Virginia Department of Agriculture and Consumer Services, the Virginia Agricultural Experiment Station, and the Hatch Program of the National Institute of Food and Agriculture, U.S. Department of Agriculture. Corresponding author. E-mail: gmp32@cornell.edu. 1098 HORTSCIENCE VOL. 51(9) SEPTEMBER 2016 to trees with similar crop load levels. The orchard was not irrigated or fertilized during the course of this experiment and weed, insect, and disease management was executed according to regional recommendations (Pfeiffer et al., 2014). An initial harvest was conducted on 29 Sept. to assess the relative maturity of the treatments using a pooled 10-fruit subsample from the treated branches on each tree which were analyzed for IEC, SPI, fruit firmness, SSC, and TA as described in ThompsonWitrick et al. (2014). Briefly, apples were weighed and visually assessed for percent red blush (0–100%). Flesh firmness was measured on the same samples, after removing part of the peel at two locations along the equator of each apple, using a Fruit Texture Analyzer penetrometer [G€uss Manufacturing (Pty) Ltd., Strand, South Africa] fitted with an 11.1-mm-diameter Effegi tip. The SPI was determined by staining the stem side of an equatorial cross section of the apples with iodine solution (0.22% w/v iodine, 0.88% w/v potassium iodine) and rating patterns against a chart, where 1 = 100% staining and 8 = 0% staining (Blanpied and Silsby, 1992). IEC was measured on a 1-mL sample removed from the core cavity of the apple using a gas chromatograph (Agilent 7890; Wilmington, DE) equipped with a flame ion detector. The calyx half of each apple was juiced in a Champion Juicer (Lodi, CA) and SSC was measured using a digital PAL-1 refractometer (Atago U.S.A., Inc., Bellevue, WA) and reported as percent Brix. TA was measured by titrating a 5-mL juice aliquot against a 0.1 N NaOH solution to an endpoint of pH 8.1 with an autotitrator (848 TitrinoPlus, Herisau, CH). A separate 50 mL juice subsample was frozen (–80 C) and shipped to the Enology and Fermentation Laboratory in the HABB1 Building at Virginia Tech (Blacksburg, VA) for total polyphenol analysis as described below. On 10 Oct., an additional 10 apples per tree were analyzed for the same parameters as mentioned above. The remaining apples from the treated branches were also harvested and transported to the Enology and Fermentation Laboratory and stored at 4 C for 1 week before processing. All other apples from each sample tree were harvested, counted (as were fruit that dropped prematurely), and reported as crop load on a square centimeter trunk cross-sectional area (TCSA) basis. On 17 Oct., apples from four of the five field replications were cleaned in a rod and reel washer and ground into a pulp using a hammer mill (RH HM100; Herbold Meckesheim USA, Smithfield, RI). There was not enough fruit from the fifth replication to produce a sufficient volume of juice for fermentation. As the apple pulp was produced, it was layered evenly onto a custombuilt rack and cloth press and pressed until juice no longer

Free amino nitrogen concentration correlates to total yeast assimilable nitrogen concentration in apple juice

Abstract Yeast assimilable nitrogen (YAN) is essential for yeast growth and metabolism during apple (Malus x domestica Borkh.) cider fermentation. YAN concentration and composition can impact cider fermentation kinetics and the formation of volatile aroma compounds by yeast. The YAN concentration and composition of apples grown in Virginia, USA over the course of two seasons was determined through analysis of both free amino nitrogen (FAN) and ammonium ion concentration. FAN was the largest fraction of YAN, with a mean value of 51 mg N L−1 FAN compared to 9 mg N L−1 ammonium. Observed YAN values ranged from nine to 249 mg N L−1, with a mean value of 59 mg N L−1. Ninety‐four percent of all samples analyzed in this study contained <140 mg N L−1 YAN, a concentration generally considered the minimum level needed in grape‐based wines for yeast to fully utilize all of the fermentable sugars. FAN concentration was correlated with total YAN concentration, but ammonium concentration was not. Likewise, there was no correlation between FAN and ammonium concentration.

Apple Pollen Tube Growth Rates Are Regulated by Parentage and Environment

A greater understanding of apple (Malus ·domestica) pollen tube growth rates can improve crop load management in commercial orchards. Specifically, applications of caustic bloom-thinning chemicals need to occur when enough, but not too many, flowers have been fertilized to achieve crop load densities that balance yields with marketable fruit sizes. In this study, the pollen tube growth rates of five crabapple (Malus sp.) cultivars were measured in the styles of three maternal cultivars at 12, 18, 24, and 30 8C after 24 hours in a growth chamber. Pollen tube growth rates were greatest for ‘Selkirk’ and ‘Thunderchild’ at 12 8C, and greatest for ‘Indian Summer’, ‘Selkirk’, and ‘Thunderchild’ at 24 8C. Pollen tube growth increased with increasing temperatures until 24 8C. There were minimal pollen tube growth rate increases between 24 and 30 8C. Overall, ‘Snowdrift’ had the slowest pollen tube growth rate of the five evaluated crabapple genotypes. At 24 and 30 8C, ‘Indian Summer’ and ‘Thunderchild’ pollen tubes reached the base of the style most frequently, and ‘Snowdrift’ pollen tubes the least frequently. Pollen tube growth rate was also influenced by the maternal cultivar, with Golden Delicious having relatively faster pollen tube growth than Fuji at 24 and 30 8C. Interactions among paternal and maternal genotypes as well as temperature after pollination reveal complex biological and environmental relationships that can be used to develop more precise crop load management strategies for apple orchards. Apple pollination occurs when pollen is transferred, often by an insect vector, from the anthers of one blossom to the stigma of another. After pollen grains are deposited, they are rehydrated by stigmatic secretions, and pollen tube growth begins (Dennis, 2000; Jackson, 2003). Genetically compatible pollen tubes grow through the stigma and style and toward the ovaries. At the end of the style, the pollen tube enters the ovary through the micropyle, where two sperm cells are released into the ovule. Fertilization occurs when one nucleus fuses with the egg cell, and the second nucleus fuses with the embryo sac, initiating seed formation (Dennis, 2000). Investigations into apple pollen biology have been underway for over a century (Adams, 1916) and have recently been reviewed by Ram ırez and Davenport (2013). In commercial apple orchards, cross-pollination between two distinct genotypes results in greater fertilization rates and thus a greater fruit set, even in orchards containing self-fertile cultivars (Dennis, 2003). Various Malus species, colloquially referred to as crabapples, are preferred pollinizers in commercial orchards due to their long bloom periods, disease resistance, and abundant pollen production (Fitzgerald, 2005). In particular, the crabapple Malus baccata ‘Manchurian’ has been widely planted in commercial orchards as a pollinizer. However, it has fallen into disfavor in recent years due to its high susceptibility to canker diseases, which could limit apple exports into Asian markets (Hansen, 2014). Other popular crabapple pollinizers include ‘Snowdrift’, ‘Thunderchild’, ‘Indian Summer’, ‘Mt. Blanc’, ‘Wickson Crab’, and ‘Chestnut Crab’. The pollen tube growth rate of ‘Snowdrift’ has been used to develop a temperature-driven pollen tube growth model that can predict the time between pollination and fertilization (Peck et al., 2016; Yoder et al., 2013). Themodel is now being used by commercial apple growers to precisely calculate when to apply bloom-thinning chemicals (Lehnert, 2014). The majority of bloom-thinning chemicals are caustic and prevent pollination or fertilization by destroying flower parts and inhibiting pollen germination and pollen tube growth. Liquid lime sulfur (calcium polysulfide) is the most studied and commercially used bloom-thinning chemical (McArtney et al., 2006). Although Snowdrift pollen tube growth can differ by as much as 3-fold among maternal cultivars, published reports on the pollen tube growth rates of other crabapple species and cultivars are limited (Embree and Foster, 1999; McArtney et al., 2006; Stott, 1972; Williams, 1965). Successful application of blossom-thinning chemicals is highly dependent on understanding the rate of pollen tube growth among different pollen donor genotypes (Jackson, 2003). Analyzing the pollen Received for publication 13 May 2016. Accepted for publication 29 Aug. 2016. This project was funded by Virginia Agricultural Experiment Station and Virginia Tech’s Department of Horticulture. We thank Abby Kowalski, Ashley Thompson, Taylor Mackintosh, and David Carbaugh for their assistance in the field and lab, Mizuho Nita for guidance with statistics, and Roger Harris and Tony Wolf for review of the manuscript. Corresponding author. E-mail: gmp32@cornell.edu. 548 J. AMER. SOC. HORT. SCI. 141(6):548–554. 2016. tube growth rates of additional pollen donors could contribute to the selection of improved pollinizers for apple orchards. The objectives of this study were to determine how pollen tube growth rates were affected by paternal (pollen source) and maternal cultivars, temperatures after pollination, and the interaction among these factors. We did this by comparing the pollen tube growth rates of five crabapple cultivars on three maternal culinary apple cultivars at four temperatures. Materials and Methods Experiments were conducted at Virginia Tech’s Alson H. Smith Jr. Agricultural Research and Extension Center (AREC) in Winchester, VA. In 2013 and 2014, pollen was collected from mature ‘Evereste’, ‘Indian Summer’, ‘Selkirk’, ‘Snowdrift’, and ‘Thunderchild’ trees located at the AREC. Only healthy blossoms in the late pink flower stage (when petals still covered the sexual organs and before dehiscence of anthers) were used (Chapman and Catlin, 1976). Pollen was collected by removing anthers from the blossoms using a fine-toothed comb, allowing them to air-dry, and then pressing the anthers through a 200-mesh sieve (74 mm between wires). Pollen was stored in microcentrifuge tubes at –12 C until use. Pollen collected in 2013 and 2014 was combined for each crabapple cultivar. Pollen viability was scored in two samples for each crabapple cultivar after 24 h at 21 C on an agarose (10 g L), sucrose (100 g L), and boric acid (10 mg L) medium by calculating the percent germination (Williams and Maier, 1977). Mature ‘Autumn Rose Fuji’/‘M.9’, ‘Golden Delicious’/ ‘M.27’, and ‘Cripps Pink’/‘M.9’ trees grown in 19-L root bags (Lacebark, Stillwater, OK) were the maternal cultivars selected for this study. Whole trees (including the bagged root system) were removed from the orchard in Jan. 2015, placed in 19-L buckets, and kept in cold storage to accumulate sufficient winter chill hours to complete endodormancy. ‘Cripps Pink’ and ‘Fuji’ trees were kept at 4.4 C for 400 h, and ‘Golden Delicious’ trees were kept at 4.4 C for 700 h; after the chilling hours had been met, trees were moved into a greenhouse (mean temperature 24 C) to force bloom. Maternal flowers used in the experiment were selected during the late pink flower stage. During each temperature trial, pollen from the five paternal cultivars was hand-pollinated onto 35 flowers from each maternal cultivar; seven unique pollinated flowers for each paternal cultivar treatment. An additional seven emasculated, nonpollinated flowers were left on the tree to serve as nonpollinated controls. All side blooms and extra flower clusters were removed from the tree to prevent cross-contamination. Flowers were tagged to identify the pollen source, and a sterilized, size 6 artist’s brush was used to apply pollen directly to the stigma. Pollen was applied in a uniform way until pollen grains were visible on the stigma. Immediately after pollination, trees were placed into a temperature-controlled growth chamber (Intellus Control System; Percival Scientific, Perry, IA) for 24 h under a 12-h photoperiod. For each maternal cultivar, the experiment was repeated at four ambient air temperatures: 12, 18, 24, and 30 C for the duration of the experiment. After 24 h in the growth chamber, flowers were removed from the tree in the order they were pollinated and placed into glass vials filled with a 5% aqueous sodium sulfite (Amresco, Solon, OH) solution. Storage vials containing the flowers were placed in boiling water for 20 min to soften the tissue. The pistillate portions were then excised from each flower and rinsed with distilled water. The styles were individually detached from the ovary using forceps and scalpel. The styles were stained with a water-soluble fluorescent solution containing 0.01% aniline blue dye (MP Biomedicals, Solon, OH) in 0.067 M K2HPO4 for pollen tube visualization, then pressed between two microscope slides (Embree and Foster, 1999). Slides were viewed at 10· and 40· with a light microscope (Eclipse Ci; Nikon, Table 1. Percent crabapple pollen germination, Spring 2015 first bloom and petal fall dates, and flower color of crabapple trees used for paternal cultivar pollen collection. Cultivars were all planted in 1999 on M.9 rootstocks. Paternal cultivar Pollen germination (%) 2015 First bloom 2015 Petal fall Flower color Evereste 65 22 Apr. 4 May White Indian Summer 75 17 Apr. 28 Apr. Pink Selkirk 85 15 Apr. 22 Apr. Pink Snowdrift 65 22 Apr. 4 May White Thunderchild 90 17 Apr. 24 Apr. Pink Fig. 1. ‘Thunderchild’ pollen tube growth in a ‘Fuji’ apple 24 h after pollination at a constant temperature of 24 C, visualized with water-soluble fluorescent solution containing 0.01% aniline blue dye in 0.067 M K2HPO4 and magnified 10· using a light microscope and a fluorescent light source. J. AMER. SOC. HORT. SCI. 141(6):548–554. 2016. 549 Tokyo, Japan) and fluorescent light source (Intensilight C-HGFI; Nikon). Histological examination for each individual style was conducted as described in Yoder et al. (2009) and Yoder et al. (2013), and included pollen germination/tube growth on the stigmatic surface (0% t

Managing apple crop load and diseases with bloom thinning applications in an organically managed ‘Honeycrisp’/‘MM.111’orchard.

Although demand for organic produce continues to increase in the midAtlantic, few apple (Malus 3domestica Borkh.) growers in the region have adopted organic management practices due to the considerable disease, insect, and weed pressure, as well as the lack of effective crop loadmanagement tools. In this study, lime sulfur (LS) and Regalia (R) were applied in different sequences (i.e., LS/LS, LS/R, R/R, and R/LS), each in a mixture with JMS Stylet-Oil, to chemically thin apple flowers in an organically managed ‘Honeycrisp’/‘MM.111’ orchard. There was also a nontreated control, a ‘‘grower standard’’ control (LS at 11 mm fruitlet diameter), and a hand-thinned control. The treatments were evaluated for their ability to reduce crop load, as well as to control powdery mildew [Podosphaera leucotricha (Ellis & Everh.) E. S. Salmon], cedar apple rust (Gymnosporangium juniperi-virginiana Schwein.), and quince rust (Gymnosporangium clavipesCooke & Peck). All treatments reduced crop load compared with the nontreated control, and after the first application of LS or R, the number of fertilized king blooms was reduced and fertilization was prevented in all side blooms. All bloom thinning treatments had more fruit peel russet than the control and russet was more severe when LS was one of the applications. Bloom thinning applications of LS and R did not reduce powdery mildew leaf infection compared with the nontreated control. Cedar apple rust incidence was reduced by all bloom thinning treatments, though some lesions were detected in all treatments. There were minimal quince rust infections in any of the treatments, including the nontreated control. These results suggest that when LS and/or Regalia are mixed with JMS Stylet-Oil and applied as bloom thinners, they can reduce crop load, and, as a secondary benefit, they can also decrease cedar apple rust incidence from infections that occur during bloom. There is a need to conduct research specifically for organic apple (Malus ·domestica) production in the mid-Atlantic region (including the states of Delaware, Maryland, New Jersey, North Carolina, Pennsylvania, Virginia, and West Virginia), so that local growers can supply the increasing demand for organic products. In 2015, organic product sales exceeded

Unique challenges and opportunities for northeastern US crop production in a changing climate

43 billion in the United States, of which produce accounted for 13% of the total sales (Organic Trade Association, 2016). However, under the current U.S. Department of Agriculture-National Organic Program (USDA-NOP) regulations, growing apples organically in the eastern United States can be challenging due to the lack of effective biological, cultural, or chemical controls for the immense insect, disease, and weed pressure experienced in this region (Cromwell et al., 2011; Peck et al., 2010; Williams et al., 2016). Additionally, crop load management options are limited in organic production because the USDA-NOP prohibits the use of the synthetically derived plant growth regulators that are used for this purpose in conventional systems (U.S. Department of Agriculture, 2016). Managing crop load in apple orchards is essential for improving fruit size and color, preventing broken limbs due to the excess weight of fruit, and ensuring adequate return bloom to minimize biennial bearing (Byers, 2003; Dennis, 2000). Thinning, or reducing the number of apples per tree and within each fruiting cluster, can also decrease disease pressure by allowing for more rapid drying conditions within fruit clusters and allowing for more complete spray coverage of the developing fruitlets. Thinning during bloommay increase these benefits and decrease the likelihood of biennial bearing cycles by eliminating excess fruit before flower bud initiation occurs (Batjer and Hoffman, 1951; Greene, 2002). In the experiment described in this paper, we evaluated bloom thinning materials applied according to output from a ‘Honeycrisp’-specific pollen tube growth model for their ability to reduce crop load and disease incidence. The pollen tube growth model uses hourly temperature data to predict the amount of time between pollination and fertilization (Peck et al., 2016; Yoder et al., 2013). This information is then used to allow a preset percentage of flowers to set fruit, while fertilization in later blooming flowers is prevented by treatment (most commonly liquid LS) with a chemical that kills the pollen tubes before they fertilize additional eggs. Liquid LS tank mixed with oil (either fish or a petroleum-based product) is a recommended chemical combination for apple bloom thinning under organic management in the eastern United States (Peck and Merwin, 2010). However, before OR-CAL, Inc. (Junction City, OR) changed the label on Rex Lime Sulfur Solution in 2015, LS was only legally approved for bloom thinning and for use with oil inWashington State (Lehnert, 2014). Additionally, LS is caustic and often causes fruit russeting, therefore reducing the value of the fruit (Peck et al., 2010). Other negative impacts of LS result from its phytotoxicity, which disrupts photosynthesis, and thus potentially yield, tree growth, and return bloom (Holb et al., 2003; McArtney et al., 2006). Additionally, LS can be a very potent bloom thinner and may over thin the crop in some years. For these reasons, additional bloom thinning product options are needed for use in the eastern United States. In prior tests, the biofungicide, Regalia (Marrone Bio Innovations, Inc., Davis, CA), made from the extracts of Giant Knotweed [Reynoutria sachalinensis (F. Schmidt) Nakai syn. Polygonum sachalinense (F. Schmidt)], was found to function as an apple bloom thinner (Peck et al., 2016; Yoder et al., 2013). Our interest in the product began after observing damaged petals in an apple disease control field experiment where Regalia was applied during bloom. We hypothesized that the Received for publication 3 Oct. 2016. Accepted for publication 11 Jan. 2017. Funding support was provided by a U.S. Department of Agriculture-Specialty Crop Block Grant administered by the Virginia Department of Agriculture and Consumer Services, Virginia Agricultural Experiment Station, and Virginia Tech’s Department of Horticulture. We thank Sierra Athey, Matt Borden, David Carbaugh, Allen Cochran II, Scott Kilmer, Abby Kowalski, Taylor Mackintosh, Jared Repass, William Royston, Jr., Ashley Thompson, and Jim Warren for their assistance with this experiment. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the authors and does not imply its approval to the exclusion of other products or vendors that also may be suitable. Corresponding author. E-mail: gmp32@cornell. edu. HORTSCIENCE VOL. 52(3) MARCH 2017 377 product was caustic and potentially damaging to other floral organs. The disease control efficacy of Regalia is reported to be from a unique mechanism of induced plant resistance that upregulates chalcone synthase and chalcone isomerase in the phenylpropanoid pathway and induces the production and accumulation of phytoalexins (Su et al., 2012). In a previous formulation, namedMilsana (Marrone Bio Innovations, Inc.), R. sachalinensis extracts were shown to decrease powdery mildew infection on cucumbers, tomatoes, begonias, and wheat (Daayf et al., 1995; Dik and van der Staay, 1995; Herger et al., 1988; Herger and Klingauf, 1990; KonstantinidouDoltsinis et al., 2006; Konstantinidou-Doltsinis and Schmitt, 1998). Regalia is currently labeled for use as a fungicide on many horticultural and agronomic crops, but its mode of action as a bloom thinner is unknown. Among the many fungal diseases that require grower intervention in the mid-Atlantic, cedar apple rust (G. juniperi-virginiana) and quince rust (G. clavipes) are formidable barriers to organic apple production because they are not effectively controlled by organically approved fungicides such as sulfur and copper (Yoder et al., 2006). An experimental formulation of R. sachalinensis (MOI-106020) that was tested before the commercial release of Regalia was found to provide cedar apple rust control (Halbrendt et al., 2010). Similarly, prior tests in Virginia indicated that control of rusts by a combination of Regalia and JMS Stylet-Oil (JMS Flower Farms, Inc., Vero Beach, FL) provides effective control of cedar apple rust and after-infection control of quince rust (Peck et al., 2016; Yoder et al., 2015). Thus, we saw an opportunity to target two of the key barriers for organic apple production in the mid-Atlantic, namely reliable crop load and disease management. The objective of this project was to test the disease control achieved while using different sequences of LS and/or Regalia , each in combination with JMS Stylet-Oil, for bloom thinning. We hypothesized that these bloom thinningmaterials would aid disease control in an organically managed apple orchard. Materials and Methods The study was conducted in an 8-year-old ‘Honeycrisp’/‘MM.111’ apple orchard located at Virginia Tech’s Alson H. Smith, Jr. Agricultural Research and Extension Center in Winchester, VA (39 06# N, 78 17#W). Trees were spaced 3 m between trees and 7 m between rows. In 2015, the year of this experiment, only USDA-NOP approved products were applied to the orchard (Table 1). Before 2015, all trees had been managed conventionally. A row of border trees on the west side of the block, as well as four trees on each end of each row with treatment trees were not sprayed for the entire season. The experiment was conducted on the remaining four rows. Treatments were applied at the dilute rate to the point of runoff with a single nozzle handgun at 1723 kPa. Maintenance sprays were applied with an airblast sprayer (Swanson Model DA-400; Durand-Wayland, LaGrange, GA) calibrated to deliver 935 L·ha. Weeds were managed by using Suppress Herbicide EC (Westbridge Agricultural Products, Vista, CA) at 28.3 L of product in 467.2 L of water/ha on 23May and 4 July. Full bloom occurred on 25 Ap

Apple Orchard Productivity and Fruit Quality under Organic, Conventional, and Integrated Management

Climate change may both exacerbate the vulnerabilities and open up new opportunities for farming in the Northeastern USA. Among the opportunities are double-cropping and new crop options that may come with warmer temperatures and a longer frost-free period. However, prolonged periods of spring rains in recent years have delayed planting and offset the potentially beneficial longer frost-free period. Water management will be a serious challenge for Northeast farmers in the future, with projections for increased frequency of heavy rainfall events, as well as projections for more frequent summer water deficits than this historically humid region has experienced in the past. Adaptations to increase resilience to such changes include expanded irrigation capacity, modernized water monitoring and irrigation scheduling, farm drainage systems that collect excess rain into ponds for use as a water source during dry periods, and improved soil water holding capacity and drainage. Among the greatest vulnerabilities over the next several decades for the economically important perennial fruit crop industry of the region is an extended period of spring frost risk associated with warmer winter and early spring temperatures. Improved real-time frost warning systems, careful site selection for new plantings, and use of misting, wind machine, or other frost protection measures will be important adaptation strategies. Increased weed and pest pressure associated with longer growing seasons and warmer winters is another increasingly important challenge. Pro-active development of non-chemical control strategies, improved regional monitoring, and rapid-response plans for targeted control of invasive weeds and pests will be necessary.