Virginia Tech Hop Yard Research Report: Executive Summary

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1 Virginia Tech Hop Yard Research Report: Executive Summary Dr. Holly Scoggins 1, Daniel Jackson 1, Margaret Aiken 1, Barslund Judd 1, and Laura Siegle 2 1 Department of Horticulture, Virginia Tech, Blacksburg, VA 2 Virginia Cooperative Extension, Amelia County, VA Funding provided by: Virginia Agricultural Council Virginia Department of Agriculture and Consumer Services/USDA DRAFT REPORT - Not for distribution, citation, or publication without permission of the authors. Presented herein is a summary of our project; a detailed report including data tables/statistical analyses is currently in review for scientific journal publication and will be provided to the once that process is complete.

2 Research Summary In the past 6 years, Virginia s craft beer industry has more than quadrupled. As the number of breweries grows, interest in producing locally-grown ingredients (hops and malted barley) has also increased. Although Virginia was historically a hop producing region, little production has occurred in the state over the past 100 years. The vast majority of hops produced in the United States come from the Pacific Northwest (PNW), and little information exist about hop production in other regions. Due to climate, shorter day length, and pest and disease pressure, hops are a very challenging crop for the Mid-Atlantic. Growers need science-based information to support their decision making. Figure 1. Hops (Humulus lupulus) growing in the Virginia Tech hop yard during the summer of 2017, as a part of the cultivar evaluation study. With that objective, a research hop yard was constructed in Blacksburg, VA in 2015 to evaluate cultivars (all bred for PNW growing conditions) and cultural practices for suitability for this region. The 0.70 acre hop yard was constructed at the Urban Horticulture Center, managed by the Department of Horticulture, Virginia Tech (USDA Hardiness Zone 6b, 2100 elevation, N & W). The soil type at the site is Duffield, which is a well-drained, fine loamy mixture. Propagules were well-rooted field plants (21 cell tray), planted on 3 6 spacing between plants, 10 spacing between cultivars, and 12 spacing between rows. Nineteen cultivars were planted in late fall of 2015 and spring of 2016; 14 of which were replicated trials (three blocks with five plants per block) and 5 mini-trials of 5 plants each. Cultivars were evaluated based on plant height, length of side arms produced, total plant weight at harvest, weight of cones (the hop flower) produced, percent dry matter in cones at harvest, and cone alpha and beta acid content. To date, these cultivars have been evaluated for performance over 2

3 two growing seasons (2016 and 2017). Presented here is a summary of our results; a full report including data tables/statistical analyses is currently in review for scientific journal publication. Cultural practices: Coir strings were tied to top trellis wires ("single string" trellising) and secured at the base of the crowns with metal W clips. At training, 2-4 bines from each hill were trained clockwise around the string (Table 1). For both the first and the second growing season, all cultivars were trained simultaneously, due to 1) large number of cultivars, and 2) lack of data on expected harvest date in our region. Though some industry recommendations exist discouraging the training of bines the first season, this did not seem logical for small-scale production. We felt that plants growing on the ground would receive less light, air movement, and be difficult to manage in regards to irrigation, spraying, and mowing in-between rows. We intended training to occur earlier in the second season, but was delayed due to heavy rainfall and work schedules. Once a hop yard is established, recommendations are to train cultivars based on expected harvest date. Event Training May 25 May 27 Harvest August 8 September 2 July 19 August 16 Table 1. Dates of training and harvest for the 2016 and 2017 seasons. Basal shoots were chemically burned back once trained bines reached halfway up the trellis ( 10 feet), using Scythe herbicide (naturally occurring fatty acids). Scythe is a contact defoliant which was applied to the bottom three feet of each plant to reduce basal shoot numbers, allowing for airflow at the bine base which may serve as a disease and pest reservoir if overgrown. The product was applied as needed to control basal shoots development until plants reached the cone production stage. Granular fertilizer was supplied twice each season as ammonium sulfate [(NH 4 ) 2 SO4] in addition to the use of water soluble fertilizer. The water-soluble fertilizer was Jack s Professional Ca + Mg, which was applied through the drip irrigation system. In total, 100 lbs. per acre of N was applied. Nitrogen application was split evenly between granular and liquid sources. Rainfall and temperature: Previous reports have indicated hops require inches of water per year, with 75-80% of that water demand occurring between mid-june and early August when plant development transitions through vegetative growth into flowering and cone production). Blacksburg, VA receives an average of 42 inches of precipitation a year (NWS, 2017); however, in 2016 and 2017 only about inches of that precipitation occurred within the critical development period of June-August (Figure 2). Blacksburg also experience extended periods of warm/hot temperatures with very little precipitation during this critical period in 3

4 both the 2016 (May 5-June 23) and 2017 (May 27 July 26) growing seasons. Despite regular monitoring and irrigation, symptoms of water stress were observed on the hops. 35 Cumulative Precepitation (inches) Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep Figure 2. Cumulative precipitation (inches) during growing seasons of 2016 and 2017, Blacksburg, VA. The winter of 2017 was relatively mild in Blacksburg, VA, and warmer than normal temperatures were experienced during the spring of February, which historically averages a maximum daily temperature of 44 F, had an average daily maximum of 55 F in 2017, including several days where the temperatures reach >70 F (NWS, 2017). Despite the warmer spring, the cumulative growing degree days (55-95 F) were less in 2017 season than in Despite the difference in growing degree days, the hops reached maturity 2-3 weeks earlier in 2017 than in 2016 (Table 1). The relationship between spring temperature and shoot emergence on harvest timing will continue to be monitored over the coming seasons. Weed control: Despite straw mulching and the installation of weed suppression fabric lining each row during plant establishment (Fig. 3), weeds have been an ongoing issue and required attention year-round. During the winter and early spring weeds were controlled using spot applications of glyphosate. However, during the growing season, all in-row weeds were removed by hand. 4

5 Figure 3. In-row straw mulch and weed suppression fabric on either side of row. Pests and pathogens: Regular scouting and other integrated pest management practices were utilized. However, one of the challenges of replicated variety trials, for any species, is the spectrum of susceptible to resistant varieties and the proximity thereof. For example, downy mildew (Pseudoperonospora humuli) impacted only one cultivar in 2016 (after harvest), but was ubiquitous in late spring of daily rains prevented spraying for a two-week period. Through careful monitoring and regular fungicide applications, the severity of damage from downy mildew was limited, but we suspect yield was impacted for several cultivars. What appeared to be powdery mildew was observed on the foliage of one cultivar (Cashmere) in late 2016 season (plants in container nursery setting, plus a few plants in trials nearby). The Virginia Tech Plant Disease Clinic returned the diagnosis of Oidium, the organism that has been described as the asexual phase of many powdery mildews. Cashmere has been reported to be highly susceptible, but whether pathogen came in with the propagules or was already present in the environment (feral plants or other cultivated plots) is unknown. This is consistent with reports of powdery mildew by growers and researchers from other states throughout the Northeast, Upper Midwest, and Mid-Atlantic. All Cashmere plants were dug and destroyed and the entire field treated. Fusarium canker (Fusarium sambucinum) was observed summer of 2017, killing fully mature bines that already contained cones. European corn borer was an issue during the 2016 season, and resulted in the death of several mature bines late in the season. Japanese beetles (Popillia joponica) were the most detrimental pest in 2017, infesting the field when most cultivars were at the burr and cone stage. Potato leaf hopper (Empoasca fabae) caused damage to foliage (hopperburn) both years. Substantial injury was seen on individual plants. Brown marmorated stink bug (Halyomorpha halys) was also observed in the field each season. 5

6 Insecticides/miticides were applied only when potentially economically-significant damage was observed. Extra care was taken as to products used and timing of application in order to reduce any impact on pollinators in the area (including the research apiary close by). Due to the potential yield impact from fungal diseases, preventative fungicide applications were used when conditions were favorable for infection. Modes of actions were rotated to discourage resistance. All pesticides were applied at label recommended rates and frequency using an Agrotec. Inc. sprayer (model ASE1090) with 100 gal tank capacity, and equipped with a Jacto model JP-42 pump and Green Garde JD9-C spray gun. Table 2 list the pesticides, rates, and purpose or target organism for all products used during this study. Timing of pesticide application and the costs associated with our spray program will be developed and made available on the Virginia Cooperative Extension (VCE) hops resource page. Product Name Active Ingredient Rate Purpose/ Target Aliette WDG Aluminum tris (O-ethyl phosphonate) 2.5 lb. / A Downy & Powdery Mildew Avid Abamectin 4 oz. / 100 gal Two-spotted mites Dipel DF Bacillus thuringiensia 1 lb. / A European corn borer Fosphite Mono- and Dipotassium salts of Phosphorous acid 2 qt. / 100 gal Downy & Powdery Mildew Kocide Copper 1 lb. /A Downy & Powdery Mildew Milstop Potassium bicarbonate 1.5 lb. / 100 gal Powdery Mildew Neemix Azadirachtin 10 oz. / 100 gal Leafhopper, European corn borer, Japanese beetle PyGanic Pyretherins 7 oz. /100 gal Japanese beetle Revus Mandipropamid 8 oz. / A Downy Mildew Roundup Glyphosate 2 oz. / gal Post emergent weed control Ridomil Mefenoxam 0.50 pt. /A Downy Mildew Scythe Pelargonic acid 7% solution Vegetative burn back Trilogy Clarified extract of neem oil 1 % solution Leafhopper, Japanese beetle Zampro Amedoctradin + Dimethomorph 8 oz. / A Downy Mildew Table 2. List of products and rates for 2016 and 2017, and their control target or purpose. Not all products were used for both seasons. Inclusion of products in this list does not indicate endorsement. 6

7 For a complete listing of Virginia-registered control options labeled for hop pests and diseases, please refer to the Pest Management Guide: Horticultural and Forest Crops, 2017 : Harvest: Harvest was initiated on when cones of a particular cultivar reached 22-25% dry matter. Bines were severed at both the top wire, and 1 meter from ground level. All bines from each crown were weighed to determine shoot biomass, and the number of bines per plant was counted at the midpoint on the string. Cones were harvested by hand and separated into usable cones, which were characterized by cones with 30% damage from insect or disease and that measured 2 cm and total cone weight (g) per plant was measured. At harvest, 50 g subsamples of cones from each cultivar was submitted to the Virginia Tech, Analytical Service Laboratory where it was analyzed for percent moisture and acid profile following ASBC method Hops-4B and Hops-14 (Table 3). As expected, the acid content for most cultivars was higher in the second year than the first. Alpha Acids (%) Beta Acids (%) Cultivar Expected Range Expected Range Alpharoma Cascade Centennial Comet Crystal Glacier Mt. Hood Mt. Rainier Nugget Sorachi Ace Southern Brewer Southern Cross Tahoma Ultra Table 3. Comparison of alpha and beta acid contents among cultivars to industry standard ranges, over the two-year study period. Note "expected range" is based on PNW values and xan vary depending on source cited. Yield: A large percentage (< 75%) of Yakima Gold, Yeoman, and Vanguard plants did not survive the winter of 2016, and the remaining crowns were removed the following spring. As previously noted, Cashmere was removed late season in Therefore, out of the 20 cultivars planted, fourteen cultivars were evaluated throughout two-year period ( ) and are included in 7

8 this report; thirteen cultivars with replication (included in Fig. 4), and one cultivar (Glacier) without replication. Figure 4. Hop yield among cultivars in replicated trials grown for both the 2016 (indicated in blue) and 2017 (red) seasons. Results are reported in lbs. per acre, extrapolated to 1,000 plants per acre, and estimated weights at 8% moisture (considered "dry hops"). Significant differences in yield have been identified among cultivars (Fig. 4). In regards to the question of whether to train or not the first season, note several cultivars had greater (or similar) yields when comparing the first season than the second. Drought, downy mildew, and training date most likely impacted second season yield. Biomass (shoot growth) and yield were well-correlated across cultivars. Several cultivars, including Cascade, Comet, Crystal, Nugget, and Chinook (part of a separate fertilizer rate study), have demonstrated reasonably good disease resistance and yield potential in our location. The yields to date have been relatively modest when compared to established yards in the PNW; however, they are consistent with other reports from the Eastern portion of the United States. Other cultivars, including Centennial, Mt. Hood, Southern Brewer, and Ultra, have demonstrated various issues at our site, including disease susceptibility, lack of vigor, and low yields. However, these cultivars will continue to be evaluated - hop plants are usually deemed "mature" by the third season. ****************** 8

9 We thank the Virginia Agricultural Council and the Virginia Department of Agricultural and Consumer Services/USDA for providing the initial funding ( ) of this research. We hope to continue our efforts if additional funding is awarded. We also thank the members of the Old Dominion Hops Cooperative for the inspiration, technical advice, and encouragement. The results of this research will be presented in two formats: 1) refereed (scientific) journal publication; and 2) a Virginia Cooperative Extension numbered publication. An additional VCE publication will focus on identification and treatment of pests and pathogens associated with hops. Additional outcomes have included two open house events, numerous grower tours, a website ( and a Facebook page ( The work has been presented at the South Atlantic Hops Conference (Richmond, VA, 2016; Asheville, NC 2017) and will be included in the upcoming conference (Blacksburg VA, 2018). We also presented a portion of this work at the National Small Farms Conference (Virginia Beach, VA, 2016). The research has also been covered in the media: f81c-57f3-b1b2-6461c3cfabb1.html 9