Development of Strata - A New Aroma Hop Cultivar

        by Shaun Townsend, Ph.D.

        Associate Professor, Senior Research


The aroma hops breeding program is a joint effort between Indie Hops, a Portland-based hop merchant serving the craft beer industry, and Oregon State University.  My role is to serve as OSU’s technical lead for this program.  Our task is to develop new aroma hop cultivars desired by the craft beer industry that are adapted for Oregon growing conditions, primarily the Willamette Valley area.  Aroma hops are valued for their very complex chemical profile that imparts unique flavors and aroma to beer although they may also be used to provide bitterness as well.  As program leader, I oversee the breeding and initial testing effort by designing and performing crosses, selecting promising genotypes, and evaluating the selected genotypes at three locations for various agronomic and chemical traits.  Indie Hop’s role is to provide sensory testing and coordinate experimental beer production with select craft brewers across the U.S.  This is the story of Strata, the first aroma hop released from this joint effort.

Hop is a rather unique plant to work with for several reasons.  First, it is a long-lived herbaceous perennial that usually does not reach full maturity in Western Oregon until the third growing season.  Second, hop is a dioecious species meaning that separate male and female plants are produced.  The female plant is the cultivated form since the mature female flower, informally referred to as a ‘cone’, is the marketed commodity used in brewing.  Finally, hop plants need to attain a much longer physical length for optimum flower production than typical cultivated plants.  Thus in the U.S., hops are normally produced on an 18-20 ft tall trellis which, as you might imagine, introduces a number of production challenges for both breeding programs and commercial hop farms.

During the establishment year, we normally provide the plants a 4’ tall bamboo stake to climb on so that the plants put resources into building a strong root system and then we string the plants (ie. provide climbing support for the full 18’ trellis) for the first time during the second growing season.  In 2010, a breeding nursery was established at the East Farm hop yard on the OSU research farm complex just East of Corvallis near the Willamette River.  Approximately two thirds of the seedlings that I had generated were established under the standard trellis (ie. 18’ trellis) while roughly one third were established on a 6’ tall “short” trellis to test the viability of that selection system in Oregon.  The idea behind the short trellis group was to evaluate those genotypes under field conditions for a growing season and then move only the superior individuals to the standard trellis.  The reasoning behind this approach is to evaluate many more individuals per unit area than we can under the standard trellis (ie. greater population density), and it’s cheaper, too.   

Thus, in 2011 the selections from the 2010 short trellis plants were established under the standard trellis and one of the individuals in this group was 9-1-331 (x331 for short).  Although the plants established in 2011 were not quite as mature as the group established in 2010 (due to transplanting), there were several genotypes that were as vigorous as the 2010 group, including x331.  As the 2011 growing season progressed and we continued to record disease, pest, and general growth data, x331 was noticeably superior to it’s short trellis siblings, and certainly agronomically equal to any siblings established under the standard trellis the previous year.  I was very excited about x331.  As the start of our harvest window in mid-August approached, I began doing a field “rub-and-sniff” test on the plants to gauge approximate harvest date and get a sense of each female plant’s aroma characteristics.  When it became clear that x331 was approaching harvest maturity, I began visiting the plant daily to sniff the cones and estimate harvest date.  Immediately, I was somewhat disappointed.  The most prominent note that x331 was exhibiting was a disagreeable, almost sour character, but when I ignored that and focused on the background character, there was an incredibly rich melody of tropical fruits mixed with dank, earthy cannabis.  Wow, I had never smelled a hop quite like it!  Each day I dutifully visited the plant and each day I was greeted first by that oft-putting sour note followed by the dank fruit bomb underneath.  Finally, the day arrived when x331 was ready to pick, and I clearly remember standing there very early one August morning trying to decide whether to tag the plant which would notify my student crew that we would harvest this plant.  I agonized a few minutes due to the funky, sour note but finally decided that I had to harvest it.  The plant was simply too agronomically strong to ignore.  I could always use it in crosses and try to breed out that disagreeable character.  And so, x331 was harvested, dried, packaged, and shipped off to Tom Shellhammer’s lab in OSU’s Food Sciences department for chemical analysis.  Harvest is so busy that I quickly forgot about it.

Approximately 6 weeks later after harvest, I was sitting outside Tom Shellhammer’s office while he was on the phone.  Daniel Sharp, one of his graduate students at that time, had a desk there and we were chatting about hops when he suddenly handed me a beaker full of hops that was sitting on his desk and said “By the way, of all of the samples that we received this year, this is the lab’s favorite one.”  I removed the lid and took a big whiff.  My eyes lit up, this was one of the most incredible hop samples that I had ever smelled.  Very rich and fruity but earthy, and full of other notes that I couldn’t quite identify but loved.  It was simply fantastic!  “This is an incredible hop, who sent this sample in?” I asked Daniel.  “It’s one of yours”, he casually replied.  Wait, what?!?  I sat there completely astonished and confused.  I smell the cones from every genotype multiple times before and as they are harvested but I couldn’t remember anything coming through the picker this remarkable.  Still very much baffled, I finally asked which genotype this was that I had submitted.  “The number is on the back of the beaker”, Daniel replied so I flipped it around and read the number.  Again, I sat there astonished and perplexed.  It was x331.  For a moment I was speechless, my mind racing trying to understand where that disagreeable character had gone when suddenly that mental light bulb clicked on.  Of course!  We dry all samples in a forced-air dryer after picking to minimize spoilage.  I rarely have a chance to smell the samples after they come out of the dryer, and until this moment, I had not had a chance to smell x331 when dry.   That disagreeable note had disappeared during drying and what was left was that delightful, pungent, dank, tropical fruit bomb.  At that moment, I knew we had something special but two more testing phases remained.

The second testing phase that our select hop plants go through involves propagating the experimental genotype and establishing these clones in small, replicated plots along with other promising genotypes and established cultivars on two cooperating commercial hop farms in the Willamette Valley.  We establish and harvest these plots while the grower-cooperator manages the plants using their standard production practices.  This is our first look at how the experimental genotypes perform under commercial production practices, and it allows us to begin sensory and experimental beer tests with craft brewers.  It was clear right away that x331 was agronomically suitable for Oregon growers, and craft brewers were very excited about this experimental hop.  They wanted it now.   After several years of consistent performance we decided to move x331 into phase 3, the final testing phase.

Phase 3, or commercial testing, involves the establishment of several acre-sized block of the experimental genotype on each grower-cooperator farm.  A commercial propagator produces the potted plants and hands that off to each grower.  The grower does all of the work: they establish the yard, maintain the plants using their standard hop growing practices, harvest, dry, and package the hops (ie. make 200 lb bales).  These bales are shipped to Indie Hops who processes the experimental hops into smaller bales or pellets, and then distributes this to approximately 100 craft brewers across the country.  The feedback that we receive from both the growers and brewers is the final piece of information that we need to release the experimental hop as a new cultivar.  As with the earlier testing, x331 excelled in the field and in the brew house with this final round of testing so the decision to release it as a new aroma hop cultivar was easy.  Indie Hops decided to name it “Strata” due to the various flavors that it can impart to beer depending on when it is used in the brewing process.  And so, that aggressive genotype that I almost did not select due to the funky aroma prior to harvest turned out to be an excellent aroma hop. 

For a little while, I was slightly bothered by the fact that I had even considered not selecting Strata that first year.  I had significant experience with aroma hops by that point in my career and yet I had been initially hesitant to select Strata.  While contemplating how to step up my game a bit so as not to miss another winner, a funny thing happened.  Both grower-cooperators are multi-generational hop farms with decades of hop experience.  During that very first commercial block harvest as X331 (as it was then known) was filling the kiln floor, one of the growers texted me and said “Ok Shaun, what have you established on my farm?  This thing smells funny, I don’t know about it.”  Suddenly feeling a whole lot better, I chuckled and texted back “Smell it again tomorrow once it’s dry”.  Later the next day, the grower texted again “This hop is amazing! It’s awesome!!”.

Yes, yes it is.