High Quality Beverage Raw Materials for the Craft Brewing Industry

Final report for LNC13-349

Project Type: Research and Education
Funds awarded in 2013: $196,953.00
Projected End Date: 09/30/2017
Grant Recipient: University of Wisconsin
Region: North Central
State: Wisconsin
Project Coordinator:
Carl Duley
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Project Information


Project continues to progress very well.  Hop and malting barley farm cooperators continue to be essential for the success of the project.  2016 was extremely wet in Wisconsin, with many regions in Wisconsin setting record annual rainfall.  Excessive rain provided both clarity and challenges to our work on hops and malting barley. 

Hops probably suffered more from the excess rainfall with a reminder once again that timely fungicide applications are essential.  Any stands that are more than 3 years old fought with Downy for the entire growing season.  Malting barley grown by farmers in Western Wisconsin once again made malting specs for craft brewers which was very exciting given the intense growing season.

Project Objectives:

Hop Emphasis:

  • Continue Hop Downy Mildew identification and control.
  • Study the life cycle of Hop Downy Mildew under Wisconsin conditions at four sites throughout the state.
  • Study pathogen persistence and reproduction under Wisconsin conditions.
  • Clean plant propagation success in the field.
  • Begin Hop soil fertility study.


Malting Barley Emphasis:

  • Continue to study spring malting barley varieties under Wisconsin growing conditions.
  • Participate in Dr. Kevin Smith's winter malting barley trials.
  • Establish Dr. Brian Steffenson's winter plot, "Vavilov Barleys' for Winter Hardiness Assessments.
  • Study fungicide timing and application in spring malting barley.
  • Gather data on nitrogen application rates on spring malting barley under Wisconsin growing conditions.


Click linked name(s) to expand/collapse or show everyone's info
  • Jerry Clark
  • Dr. Amanda Gevens
  • Tim Rehbein



Hop Disease Research:

  1. Simple growing-degree day models can successfully predict hop downy mildew basal spike emergence in the spring
  2. Winter soil temperatures influence the severity and timing of hop downy mildew disease severity and timing in the spring
  3. Oospores of P. humuli are produced in Wisconsin hop yards and persist in the soil
  4. P. humuli populations resistant to the fungicide mefenoxam are present in Wisconsin hop yards

Hop Soil Fertility Research was not a major emphasis for this project, but we did get a start on exploring the nutrient requirements for hop production in Wisconsin.  We assume that hop soil fertility requirements are different for Wisconsin production than it is for production in the Pacific Northwest. 

Malting Barley Research focused on varietal research for both spring and winter malting barley 2 row varieties, fertilizer rate trials, fungicide trials.  The purpose was to study if 2 Row Malting Barley could be grow in Western Wisconsin that would meet quality standards and be economical for farmers.

Materials and methods:

Hop Disease Research:

Hypothesis 1: Late winter/spring air and soil temperature data was collected using a Spectrum 1000 Series weather station and Spectrum soil temperature probes at four collaborating hop yards.  Hop yards were visited weekly/biweekly from late March to late April and scouted for hop shoots showing characteristic downy mildew symptoms.  These shoots are classified as ‘basal spikes’.  The date at which the first basal spikes were observed was recorded.  This data collection occurred from 2015-2017.  Weather data was processed using “R” (https://www.R-project.org) statistical software.  Accumulated degree-days were calculated using several base temperatures for each location/year/emergence date combination.  Degree-day calculations for each base temperature were averaged over all years and used for model selection based on certain statistical parameters such as range, variance, and coefficient of variation.  The day-of-year (DOY) at which these newly calculated degree-day thresholds occurred was also calculated and compared to actual emergence dates. 

Hypothesis 2: Experiments were performed to artificially “manipulate” the soil temperature at two collaborator hop yards over the winters of 2016/17 and 2017/18.  Treatments consisted of snow removal to remove insulation and lead to colder soil temps, a mulch layer to add insulation and warm soil, and an unaltered control.  Treatment plots were five feet long within a hop row with five foot buffers between each plot.  Treatments were replicated five times with a randomized complete block design.  Experiments were conducted with ‘Nugget’ variety hops of similar ages at both hop yards.  Spectrum button loggers measuring temperature were buried at 4 and 10 cm in one of each treatment plots at both locations to ensure the appropriate temperature changes occurred.  Mulch was applied as intact straw bales.  Snow removal was performed by grower collaborators as accumulation occurred.  In the spring, counts of healthy hop shoots and basal spikes in each plot were made at time of emergence, then 3, 7, 10, and 14 days post-emergence.  Data was analyzed for differences in the number of infected basal spikes between treatments and the timing of this spike emergence.  

Hypothesis 3: Healthy and infected leaf and stem hop plant tissue was screened for the presence of P. humuli oospores.  Plant tissue was cleared by boiling in ethanol followed by a 10% bleach soak for several hours.  Cleared tissue was visualized under a light microscope for characteristic double-walled oospores.  Soil samples were collected from four hop yards at spring, summer, and fall time points in 2016.  At each collection, ten samples of soil taken from the top 2-3 inches of soil at the base of hop plants were gathered from arbitrary locations within the hop yard.  10 g from each of the ten samples per time/location were aggregated and homogenized with a mortar and pestle.  The resulting 100 g aggregate sample was suspended in water and sonicated for 5 minutes at 70% duty cycle.  The resulting slurry was strained sequentially through sieves 250, 75, 50, and 25 um in size.  The material remaining on the 25 um sieve was collected and layered onto 20 ml of a 70% sucrose solution and centrifuged to separate oospores from soil.  The supernatant, which would contain any present oospores, was sieved again through a 25 um sieve and rinsed.  The remaining material was collected in a 15 ml tube.  Six 30 ul subsamples from this solution were observed under the microscope and oospores were counted in each.  Based on these counts, the total number of oospores in each soil sample was back-calculated. 

Hypothesis 4: Colony isolates of P. humuli were collected from 8 hop yards in 6 counties in 2014-2017.  These isolates were tested for insensitivity to a commonly used and highly effective fungicide chemistry utilized for hop downy mildew control: mefenoxam.  This screen was performed as a leaf disk assay based on previously performed work in the Pacific Northwest.  In short, leaf disks were cut from hop leaves from greenhouse-grown plants.  Leaf disks were placed onto Petri plates with water agar or water agar amended with a discriminatory dose of mefenoxam (25 ug/ml).  Seven leaf disks were placed on each plate, with the top leaf surface in contact with the agar.  Fourteen total leaf disks were each inoculated in three discrete locations with a standardized suspension of P. humuli sporangia collected from the field.  After incubating for 5-7 days, each inoculation site on both control and treatments plates was observed for the presence of P. humuli sporulation.  An isolate was determined to be resistant if the amount of sporulation on fungicide treatment plates was at least 50% the amount of sporulation on control plates.  Further assays conducted on a range of fungicide concentrations were performed to calculate ED50 values for each isolate.  These values are useful for tracking sensitivity changes within a population over time.  A total of 80 isolates grew sufficiently for full analysis. 

Hop Soil Fertility Research:  the first year, 2016 that we studied hop soil fertility, we only looked at the biomass produced in the whole plant and in the hop cones alone.  We did this for 3 hop varieties in two locations (farm cooperators).  In 2017 we expanded this research by adding 3 different nitrogen rates. See the following for the protocol used: Hop N fertility protocol_051817

Malting Barley Research trials were in cooperative with UW-Madison Extension and the University of Minnesota.  All plots were planted using a randomized block design.  see fungicide example 17213 Buffalo Co. Barley Trial  

  • 28 - 38 winter malting barley varieties were planted in October, 2015, 2016, and 2017 and about 70% did very well.  Proteins seemed a little high for craft brewing malting quality, but more test years are needed to understand their true characteristics.  The unusually late freeze allowed these plants to grow larger than desired, and as of this report 85% of the varieties seemed to have survived the winter.  Farmers are very excited about the possibility for winter barley as they seem to yield higher, have less disease issues, fit better into the rotation, and provide better cover on steeper soils than spring barley.  One Buffalo County farmer did contract with a malter to grow 45 acres of a winter malting barley.
  • Spring varieties were planted in two locations, Buffalo County and Chippewa County.  Nine varieties were included in 2015, 2016, and 2017 replicated variety plots.  All were malted by the USDA Cereal Grains Unit in Madison, WI.  Six of the varieties showed good malting qualities, two varieties seem to have consistently high protein levels undesirable in brewing, and one heritage variety had many agronomic characteristics that made it suffer to a point that it was not suitable to harvest.
  • A fungicide plot was also included in two locations in 2016 and 2017.  Plots included no fungicide, fungicide for leaf diseases only, fungicide at heading only and two fungicide applications.  All were replicated with two different varieties of barley (Pinnacle and Genesis) and each was replicated four times.  Data is still being analyzed, but preliminary data looked like there may be some advantage to the Genesis variety and maybe just fungicide at heading.  
  • A nitrogen fertilizer trial was conducted in 2015, 2016, and 2017 with Pinnacle and Genesis barley with rates from 0 to 120 pounds of nitrogen.  
  •  Four graduate students from the University of Minnesota attended the seminar and explained their major areas of research.
Research results and discussion:

Hop Disease Research:

Hypothesis 1: Growing degree-day thresholds for basal spike prediction have been developed in other hop growing regions, but the prediction threshold of 111.3 degree-days (air temperature) has been reported inaccurate for Wisconsin by growers.  Our goal was to assess the accuracy of this value under local conditions and potentially develop a more accurate predictive threshold.  When on-site weather data was used to calculate the DOY at which this 111.3 threshold occurred in each year, this date was often very close to the actual date of observed emergence when the degree-days were calculated with a specific adjustment described with the original model in the Pacific Northwest.  We believe that the reported inaccuracy by growers of this original number was due to the lack of this adjustment when calculating growing degree days.  Preliminary calculations of a “new” degree-day threshold based on three years of on-site data produce DOY predictions that near the observed date of emergence and are fairly consistent from year to year. 

Hypothesis 2: Preliminary results after one year of data collection indicate that significant differences in the number of infected basal spikes emerging in different treatment plots do not occur.  In other words, removing snow or applying mulch did not appear to have an impact on disease emergence in the spring or this timing of this emergence.  Significant differences in the total number of hop shoots emerging were present between the snow removal treatments and the mulch/control treatments.  Where snow was removed there were often significantly fewer hop shoots that emerged. 

Hypothesis 3:  Oospores were identified in both stem and leaf tissue, but were much more numerous in leaf tissue.  Oospores were only found in hop tissue that was infected with P. humuli and was undergoing necrosis.  No oospores were found in healthy plant material or leaf parts that were still green and healthy in appearance.  Thus, oospores are being produced here in Wisconsin.  Very few oospores were found in all soil samples screened.  The few that were found were not verified to be P. humuli due to the extremely low numbers detected.  Findings ranged from 0-1.8 oospores per gram of soil.  In other regions oospores were detected at levels of approximately 14 oospores per gram of soil. 

Hypothesis 4: While mefenoxam has been demonstrated as highly effective in controlling hop downy mildew disease epidemics, this particular chemistry is especially susceptible to the development of pathogen resistance because it inhibits a single-site in the pathogen RNA synthesis pathway.  Thus, a single mutation within the pathogen can restore functionality and render the pathogen immune to the fungicide.  Since hop downy mildew is a polycyclic disease where large amounts of spores are produced frequently, large shifts in population sensitivity can occur within a single growing season in some cases.  Additionally, resistance to this fungicide has been well documented in other hop growing regions where many growers have sourced plant material, potentially importing resistant strains in the process.  Growers are very interested in the sensitivity status of current P. humuli populations as they make disease management decisions.  Insensitivity to mefenoxam was detected in 38 out of 80 total isolates tested.  This represents 47.5% of all isolates tested.  ED50 calculations are still in progress. 

Hop Soil Fertility Research initial data indicates that we may be over recommending nitrogen fertilizer to hops in Wisconsin.  Data for 2017 is still being analyzed and a proposal has been submitted for two additional years of data collection to build our confidence in the data. 2016 data Hop-Fertility-2017-seminar-v4

Malting Barley Research Results:  We are waiting for final results from USDA and the University of Minnesota so three years of data can be combined for accurate research results.  These findings will be added to this report in February or March following completion of tests.



Research conclusions:

Hop Disease Research:

Hypothesis 1: Preliminary data indicates that a useful predictive model will be feasible for Wisconsin hop downy mildew.  

Hypothesis 2: Experiments still in progress.

Hypothesis 3: In the hop downy mildew life cycle, oospores are generally considered to play an insignificant role in driving disease epidemics within the hop yard.  Though oospores are being produced in Wisconsin hop yards, we were not able to detect large numbers within the soil.  This may be due to inefficiencies or limitations in our screening process, or the relatively limited time that hops have been produced in state has not allowed for significant numbers to yet build up in soil to detectable levels. 

Hypothesis 4: While pathogen insensitivity to mefenoxam has been detected in Wisconsin, we do not currently recommend that growers abandon use of this product.  Rather, careful monitoring in the coming years is recommended.  Growers are encouraged to closely observe how mefenoxam works in their hop yard if applied and to follow all resistance-management guidelines outlined on the product label. 

Hop Soil Fertility Research:

It is too early to make final conclusions about the hop soil fertility research.  We need another two years of data before changing our soil recommendations.  First year data does seem to indicate that our current nitrogen recommendations are a bit higher than needed.  It also seems to indicate that split nitrogen applications are necessary in our sandy soils, but may not be necessary in our heavy fine textured soils.  We have applied for an additional grant to continue these trials for two additional years.

Malting Barley Research Emphasis:

These conclusions will be updated following the analysis of all three years of data.  For now, the data seems to indicate the following:

  • A total of about 70 pounds of total nitrogen maximizes our yields for 2 row spring barley.  This is consistent with current UW-Extension soil test recommendations.  We will look at additional varieties and nitrogen application levels.  Higher levels of nitrogen does not increase yields but also tends to increase protein levels that are too high to meet malting quality requirements.
  • We can consistently produce malting quality barley under Western Wisconsin weather conditions.
  • Winter malting barley varieties can be consistently grown in Western Wisconsin, but winter survival is very dependent on variety and weather conditions.  There has been interest from two different companies for winter varieties.  Winter varieties meet farmers rotation and allows for better cover crop production needs.
  • Fungicides are necessary to meet quality standards for malting barley in Western Wisconsin.  We will continue to analyze the data and look at current predictive models to see if we can reduce alliance on the routine application of fungicides.


Hop Emphasis - Presentations and Meetings:


Malting Barley Emphasis:

Participation Summary
13 Farmers participating in research


Educational approach:

Our educational approach was really three different approaches for both hops and malting barley:

  • On- farm research and demonstrations with farmer involvement.  Hop harvesting samples were done either by hand or with equipment owned by farmers.  Malting barley planting and harvesting was done with leased plot sized equipment.  In both cases farm cooperators came to realize the importance of replicated plots and research design.  farmers helped with data gathering and experienced the differences seen across treatments and within the plots themselves. 
  • Farm field days were held each year at various locations on both hops and malting barley.  Most times these were done at demo/research locations but not always as field days were moved around the state.  Guest speakers were used at field days with very short formal presentations, and discussion was always encouraged.
  • Large and small group meetings were held with a state meeting on hops each year that was moved around the state with the goal of having the meeting in a different hop growing area each year.  We did hold a statewide webinar meeting on malting barley with limited success.

Project Activities

Summer Hop Field Days
Annual Hop Seminars
Malting Barley Field Days
Malting Barley Tours

Educational & Outreach Activities

612 Consultations
12 Curricula, factsheets or educational tools
35 On-farm demonstrations
8 Published press articles, newsletters
5 Tours
44 Webinars / talks / presentations
16 Workshop field days

Participation Summary:

210 Farmers participated
35 Ag professionals participated
Education/outreach description:

It is hard to separate research and outreach activities for the hop and malting barley projects.  All of the demonstration plots and replicated research plots were located on property owned by farm cooperators.  More formal outreach was organized around hops because of great statewide and regional interests and a greater proportion of the project was targeted at hop research and education.  Also, the project had a major portion of funding that supported a PhD student and her work.

Hop activities:  An annual hop conference was held each year along with at least one hop field day. Presentations were given by local, regional and national hop experts.  All presentations were also made available of the webpage managed by the PI for the project.  https://buffalo.uwex.edu/agriculture/barley-and-hops/

A vast majority of one-on-one consultations were also directed at hop production due to the state and regional interest in hop production. Most hop producers also get started on a very small scale therefore bringing the numbers of contacts to a high level.

Malting Barley activities:  Most malting barley educational activities revolved around research plots and tours.  The plots were located in two counties, 50 miles apart and on very different soil types.  An annual field day was held at each location and followup was done on a one-to-one basis.  More traditional farmers made up the bulk of the participants and many were not interested once the production requirements and marketing challenges were explained.



Learning Outcomes

114 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
38 Agricultural service providers reported changes in knowledge, skills, and/or attitudes as a result of their participation
Key areas taught:
  • Hop disease identification.
  • Hop insect identification.
  • Weed control in hop yards - using approved herbicides.
  • Hop downy mildew and powdery mildew disease control
  • Hop yard construction and general hop production management.
  • Malting barley varieties for Wisconsin growing conditions.
  • Malting barley disease identification and control.
  • Malting barley fertilization and general production management.

Project Outcomes

150 Farmers changed or adopted a practice
Key practices changed:
  • Forty-five hop producers add irrigation to their hop yards to increase production to more competitive levels. Most also added drip irrigation because of its cost and efficiency. Findings are from survey results of Wisconsin hop producers in 2013 versus 2016.

  • In 2013, 60% of Wisconsin hop producers indicated they could not recognize hop downy mildew or hop powdery mildew in their hop yards. 85% of Wisconsin hop producers indicated that they were familiar with and could identify hop downy and powdery mildew in their hop yards in the 2016 follow-up hop production survey.

  • 90% of Wisconsin hop producers indicated they used some type of cultural control in the fight against hop downy mildew in their hop yards. This compares with only 35% reporting using cultural controls for disease control in 2013.

  • Hop producers have designed fungicide treatment programs around timing, weather conditions, cultural practices, mode of action, and pre-harvest interval to reduce chances of the build up of resistance in fungicides and produce better quality hops that will be acceptable to brewers.

  • Seven farmers in Buffalo County formed an organization called Buffalo County Barley Society and have begun growing barley, currently malted at Rahr Malt, Inc. 95% of the barley is planted no-till and all has met strict malting quality requirements for the past three years.

  • Barley producers have developed fungicide programs to reduce Fusarium infection to acceptable levels for the malting barley industry.

  • Barley producers are now planting cover crops following harvest to build organic matter, provide soil erosion protection, and in years where needed, provide supplemental fall pasture for beef cattle.

5 Grants applied for that built upon this project
3 Grants received that built upon this project
Success stories:

Seven farmers in Buffalo County Wisconsin have organized into a group they call the Buffalo County Barley Society.  They have grown up to 350 acres of malting barley that has been malted at Rahr Malt, Inc. in Shakopee, MN and has all been purchased by one Wisconsin brewer.  That have received a small premium for their barley due to the barley being very high quality.  Four of these farmers have also hosted malting barley research trials and field days.  In 2018 they have the opportunity to increase their production considerably due to increasing demand for local malting barley brewers.  Prior to the start of this study the was no malting barley grown in Buffalo County for many years.  These farmers are also looking at malting barley production providing soil health benefits by longer growing season for cover crops and better erosion control potential than other cash crops.

Testimonial from farmer involved in the Hop Research Project as filmed by SARE North Central Region: https://www.youtube.com/watch?v=b3mhsCga9D4

Testimonial from a farmer that has hosted Malting Barley Research Plots as filmed by SARE North Central Region:  https://www.youtube.com/watch?v=ySuScQHSkSs 



Hop soil fertility is an important area of study that needs additional research and education.  We have one year of very preliminary data, and a second year with data that is more detailed, but not near enough data to make sound reliable recommendations.  A SARE Partnership grant has been submitted to continue the hop soil fertility study.

Post harvest quality continues to be a challenge for hop producers.  We have applied for a grant to study post harvest drying and handling of hops under Wisconsin conditions.

Study also needs to continue in barley production for developing a disease (Fusarium) prediction model so fungicides are only applied when needed.  Currently, fungicides are applied every year because the risk of having too high of infection and selling your barley as feed rather malt is too high.  Feed barley is currently at $1.65/bushel where malt barley is at $5.25/bushel.  We have funding for one more year through a different grant to continue our fungicide trials, and will look for future funding opportunities.


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Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.