CHAPTER 2

The Hop Plant

The flowers of the hop bine, called hop cones, are rich in lupulin, a sticky resin that contains the acids and essential oils that flavor beer.

With heavy bines towering high above you, being in a mature hop yard in late summer is somewhat like being in a very orderly forest. The bines wrapping around their coir are as thick and strong as cables. The mass of broad, deep green leaves soaks up the sunlight, pumping its energy into the formation of the flowers. Belowground, the plants’ robust system of roots and rhizomes is essentially as large as what grows above, drawing up nutrients and water from the soil to nourish the massive amount of vegetation overhead. It amazes me to think of how effectively people have harnessed the incredible natural energy and characteristics of the hop—all to harvest the nuanced balance of acids and oils encased within the hop flowers for the purpose of flavoring beer.

Maturing hop bines in the pilot hop yard.

The plant family Cannabaceae has two famous members coveted by humans around the world—the genuses Cannabis and Humulus. Cannabis’s most famous species is Cannabis sativa, commonly referred to as marijuana or hemp, which has been used throughout human history for fiber to create cloth and rope, as well as for medicinal purposes. Though in modern times Cannabis sativa has become notorious for its use as a recreational drug, the plant is once again becoming increasingly recognized for its medicinal value. Cannabis’s sister genus Humulus boasts its own famous species Humulus lupulus, better known as the common hop. The visual, aromatic, and medicinal similarities between hops and marijuana are striking and have even inspired some marijuana growers to go so far as to attempt to graft hops onto their pot plants and some brewers to infuse their brews with the dried leaves and buds of Cannabis sativa. As marijuana achieves legal status in some states, marijuana growers and scientists that study hop genetics have begun to connect, finding out that (botanically speaking) they have quite a bit in common and can learn from each other, especially when it comes to cultivating and breeding plants for particular aroma qualities.

Once the hop plant reaches the top of the trellis it switches gears. Instead of focusing on climbing upward, it channels its energy into putting out the lateral sidearms on which the flowers will form. In the early stages these flowers are tiny balls called burrs.

The hop is a vigorous plant that with sufficient support can reach heights of 40 feet (12.2 meters). Feeding this enormous amount of vegetation is a vast underground root system penetrating 15 feet (4.6 meters) or more into the soil. Illustration by Dahl Taylor

How Hops Grow

The hop is a perennial bining plant that dies back in the winter and begins to grow again in the spring, regenerating year after year in temperate climates. This cycle of dieback and growth is particularly dramatic in the hop. Under the right conditions hops can grow as much as 1 foot (30.5 centimeters) a day. In just one season, given a high enough support system, it can grow as tall as 40 feet (12.2 meters). While its climbing bine regenerates each year, the hop’s underground system of roots and rhizomes is a permanent thing. Hop roots dig 15 feet (4.6 meters) deep or more into the soil to absorb nutrients, minerals, and water to send up to feed the plant. Hop rhizomes are a critical part of this underground system, but they are different from roots. Rhizomes are actually stems that grow horizontally just beneath the surface of the soil. They can grow up to 5 feet (1.5 meters) in length.

Hardy roots and rhizomes easily overwinter below ground. In fact, the winter season is as necessary to the hop as the summer. To produce the valuable flowers used in brewing beer, the plant’s roots and rhizomes must experience a cold period of at least six to eight weeks, during which the hop can lie dormant. When spring comes, the hop wakes up and buds on the rhizomes send up shoots. This entire root and rhizome structure is referred to as a crown. The crown of a mature hop plant can be as wide as 4 feet (1.2 meters) across.

Hop plants are dioecious—a term describing a version of plant sexuality in which plants are either male or female. This is different from many other plants that have flowers with male reproductive parts and flowers with female reproductive parts located on the same plant; this type of plant is called mono ecious, essentially meaning unisex. One monoecious plant can fertilize its own flowers, creating its own seeds and thus reproducing itself. For a dioecious plant to produce viable seeds a female plant must be in close enough proximity to a male plant to be pollinated.

Hops have an extensive root system comprising both roots and rhizomes that penetrates deep underground in search of water and nutrients.

The hop rhizome is essentially part of the root system but is technically an underground stem. Buds sprouting from the rhizome develop into shoots, which upon emerging aboveground produce leaves and seek to climb anything they can wrap themselves around.

However, modern hop growers don’t want male hop plants around. They choose to propagate new hop plants from existing rhizomes rather than growing male plants for pollination. There are a few reasons for this. The first, and maybe the most compelling, reason is that the hop flowers produced by male plants, which don’t even look like the cone-shaped flowers produced by the female plants, do not have what it takes to make good beer (more on this later). Second, hop growers do not want their female hop plants to be pollinated and go to seed. Seeds get mixed in with the hop flowers and produce added weight, which brewers, who buy hop flowers by the pound, do not want to pay for—especially since the seeds add nothing to the brewing process. In fact some brewers believe that hop seeds lend a bad flavor—something like rancid butter—to the beer. And finally, male hop plants produce a ton of pollen that, because of their high elevation, is carried on the wind to female hop plants far and wide.

The male plant produces flowers very different from the female plant in appearance. Because their flowers do not contain lupulin, the crucial element in hops for making beer, male plants are not welcome in commercial hop yards.

In fact, before people started propagating hops from rhizomes, hop farmers would need to keep only one male plant per one hundred female plants in their hop yards. This prolific pollination effort on the part of the male hop plant results in undesired genetic crosses that can sprout up anywhere in the hop yard—even nestled within the established crown of a cultivated variety, its shoots indiscernible to the hop grower. Hops are heterozygous, meaning that a seed produced by a hop plant of a particular variety is unlikely to grow into a plant of the same variety as its parent. For this reason, when putting in new plantings people relied on hops propagated from rhizomes as it was the only way to ensure you were getting the variety you wanted. When Europeans arrived in North America, it is likely they did not bring hop seeds but instead brought plant cuttings and rhizomes.

All this is why only growers who are working on developing new varieties of hops keep male plants, and these are kept in isolation from commercial hop yards. If you have wild hop plants growing in the vicinity of your hop yard, keep an eye out for male plants. It is a good idea to remove them so they do not cross-pollinate with the female hops you are cultivating. However, instead of completely destroying the plant, you may want to consider propagating a rhizome or cutting a sufficient distance from your hop yard to avoid cross-pollination in order to preserve the wild plant’s genetics.

Female hop plants produce hop cones that contain lupulin. Most hop plantings contain only female plants, which are reproduced by propagating hop rhizomes.

Left to reproduce naturally, occasionally a hermaphrodite hop plant will occur that produces both male flowers and female hop cones.

Hops’ Seasonal Growth Cycle

Hops grow big, and they grow fast. To achieve this level of growth they need an incredible amount of energy from the sun, nutrients from the soil, and lots of water. In Chapter 6 we will track the hop as it grows and give detailed instructions for cultivation at each stage, but first let’s take an introductory look at this incredible process.

In early spring the rhizomes in the plant’s crown begin to send up a lot of shoots. It is up to the hop grower to prune these shoots back, selecting only a small number of the strongest shoots to begin to train to grow up the support system—whether that’s a trellis system in a hop yard or a pole, rope, or lattice in a small garden or the side of a building. Pruning is critical because the grower producing hops to sell to brewers wants the vigorous hop plant to put all its energy into producing the all-important flowers, not a jungle of Jumanji-like bines.

Hops are a vigorous, fast-growing plant that under the right conditions can grow as much as 1 foot in a single day.

Bines climb their supports differently from vines, which send out thin, spiraling shoots that wrap around anything within reach, enabling them to climb. A shoot from a bining plant like hops, on the other hand, uses tiny barbs called trichomes to climb upward by twisting itself around and up basically anything it can reach, even other shoots from the same plant. These trichomes make hop bines very prickly. If you look at them under a microscope, each trichome is shaped like a miniscule anvil, sharp on either end. Once the hop reaches the top of whatever support it is climbing, it starts to focus on putting out horizontal shoots called sidearms. Established plants in their second or third growing season will reach this stage between late June and early July. During midsummer these side shoots form the buds that turn into the hop flowers. The buds start out as tiny, bright green beads of vegetation called burrs— which grow into papery, pinecone-shaped flowers called cones.

Close-up of trichomes on a hop bine. Trichomes are the extremely tiny barbs on the surface of a hop bine that enable it to grip and climb. Illustration by Dahl Taylor

The outer scales of the cones, which look like green petals, are called bracts. The more fragile interior petal-like scales are called bracteoles. Glands located at the base of the bracteoles produce a bitter yet fragrant yellow resin that, at a glance, looks something like pollen. This resin, called lupulin, is made of essential oils, as well as the alpha and beta acids that lend beer its distinctive bitterness. Alpha acids provide the bitter flavoring and act as a preservative. Beta acids provide some bitterness as well as aroma. Each hop variety has its own unique balance of acid levels, which also vary from year to year depending on growing conditions. This composition of alpha and beta acids and essential oils will determine what type of beer the hops will be most useful for.

This cross section of a hop cone shows the bracteoles lined with lupulin at the center of the cone. Illustration by Dahl Taylor

During hop harvest the bines are normally cut and taken to a central location for harvesting. A section of the bine growing out of the ground about three feet in length is left behind. The remaining bine continues to photosynthesize, producing energy that is stored in the root system for the following spring. In the event a hop bine is not cut, as in the case of a wild hop, the additional vegetation will produce even more energy to feed the root system. The unharvested hop cones will simply brown and dry as they age. Once hard frost occurs, the vegetation aboveground dies back and the hop crown goes into a dormant state for the winter months.

Alpha and Beta Acids: The Chemistry of Hop Cones

When it comes to hop cones what brewers are really interested in is chemistry. The taste of a given beer is greatly influenced by the nature of the chemical compounds in the hops that were used during the brewing process. These compounds are found within the lupulin, which contains soft and hard resins, hop oils, and polyphenols. The soft resin contains two acids important to bitterness in beer— alpha acid and beta acid. Hop varieties used for their bitterness are called “bittering hops.” The levels of alpha and beta acids in hops differ with the variety of hop, the location in which it is grown, and the growing season. Because levels of alpha and beta acids are so important to brewers, a sample from each variety you grow will have to be submitted to a laboratory for analysis to determine the percentage of these acids. This information will have to be made available to the brewer before purchase and is normally included on the packaging’s label. Because of the current rage for highly hopped beer such as India pale ales, alpha acid—responsible for bittering—currently gets a lot more attention than beta acid, but the levels of each present in the hop are both important, as is the relationship between them.

ALPHA ACID

Alpha acids are the chemicals that make hops anti-bacterial. They also enable hops to provide beer with bitterness. Alpha acids primarily include the acids humulone, cohumulone, and adhumulone. Interestingly, alpha acids are not at all bitter, or even soluble, until they spend some time in the brew kettle. During boiling, alpha acids are isomerized. Isomerization is a chemical reaction, induced by light or heat, that gives a chemical compound a makeover of sorts: a reconfigured molecular structure that can bring with it new characteristics. After this makeover, the alpha acids, now called iso alpha acids, become soluble and intensely bitter. Since the process requires time, bittering hops are added to the brew kettle at the beginning of the boil, which usually lasts for about an hour.

The hop cone’s exterior comprises green papery petals called bracts that overlap somewhat like the scales of a pinecone. The bracts protect the cone’s interior, where the precious alpha and beta acids, along with the hop oils, are stored within the yellow grains of lupulin.

Alpha acids are so important in beer that alpha acid itself, in extract form, is traded as a commodity. American hops both wild and domestic have traditionally been associated with a high level of bitterness. Hops can have alpha acid levels ranging from zero to upward of 20 percent. Since bitterness has become a sought-after characteristic in beer, new hop varieties are being developed that have really high levels of alpha acids. Most of these varie ties, referred to as high-alpha hops or even super-alpha hops, are proprietary and hail from the United States—but some are also coming out of New Zealand.

BETA ACIDS

Beta acids include the acids lupulone, colupulone, and adlupulone and are also responsible for bitterness in hops. Unlike alpha acids, beta acids release their bitterness primarily through the process of oxidation rather than isomerization, meaning that the acids break down and release bitterness when exposed to oxygen over time. The bitterness of beta acids emerges during brewing processes that involve air circulation, such as dry-hopping, or take place over extended periods of time, such as long-term fermentation. Beta acids can make up zero to 10 percent of the hop. Iso alpha acids tend to lose their power with age. This is where the beta acids come in, picking up the slack when the bittering power of the iso alpha acid begins to wane. It is the combination of alpha and beta that are important to the bitterness of the beer, and that is why brewers often look at the different levels as a ratio instead of a percentage.

Hop Varieties

Standing with a group of farmers, brewers, and plant scientists in a newly planted hop field in Geneva, New York, on a blustery August day, Dieter and I listened to Steve Miller—the one and only New York State Hops Specialist working for Cornell Cooperative Extension—answer a question that arises often: How should hop growers on modern-day, start-up hop farms in the East decide what varieties to plant? A long-time extension staffer focused on vegetable production Miller shifted gears in 2011 to become the extension’s hop specialist, helping New York farmers expand the hops-growing renaissance playing out in the state, where the number of acres in hops production has grown significantly in the past ten years. But like others engaged in the East’s effort to meet the demand for local hops, he knows the answer to this question is not easy. There are some varieties considered safer than others, but it will take experimentation by growers and scientists alike to really refine the options. Like the test plot we were standing in at the New York State Agricultural Experiment Station—where hop plants just 1 foot (30.5 centimeters) high were wrapped around strings suspended from a trellis system elevated by rows of newly erected 18-foot (5.5-meter) poles—hop farmers in the East are starting from scratch.

But these pioneers are not alone. Plant scientists at field research facilities such as Cornell University’s New York State Agricultural Experiment Station and the University of Vermont’s Hops Project at Borderview Research Farm are trying to figure out which of today’s modern hop varieties are best suited to growing conditions in New York and New England. Their research is relatively new, and the fact that this perennial crop doesn’t come into full production until its third year means their results are still a few years out. Meanwhile, the last best knowledge on the science of hop growing in this region is found in historical documents that people like Miller are dragging out of the archives.

Hop Oils, Aroma, and Flavor

Although bitterness plays a major role in beer, any beer aficionado will tell you it is only one member of a diverse cast. All the important character actors that give a beer its depth of flavor and aroma are found in the hop’s essential oils. These essential oils are volatile, meaning that they turn from a solid or liquid into a gas. While bittering hops need to spend time in the brew kettle to release their bitterness, the aroma and flavor properties contained in the hop oil will completely vaporize during prolonged boiling and be lost. Brewers add aroma hops at the end of the boil to release the essential oil’s properties without losing them. Hops varieties valued for their essential oils are referred to as “aroma hops.” Because of the time at which they are added to the boiling wort—the liquid containing the sugars extracted from the malted barley—they are also called “finishing hops.” Flavor imparted by essential oil is due to organic odor compounds such as humulene, myrcene, and caryophyllene. For example, humulene is associated with a woody/piney aroma, and myrcene is associated with an aroma described as green and resinous. Essential oil can be present in hops at a level between 0.5 and 4 percent. One interesting thing about hops grown in the East is that they seem to contain a higher level of essential oil than hops grown in the Northwest.

Cornell University’s 1-acre (0.4-hectare) hop yard at the New York State Agricultural Experiment Station located in Geneva, New York, where researchers are conducting diverse hop variety trials and experimenting with methods of disease and insect control.

There are over two hundred different varieties of hops, some newly developed and some from times gone by. Hop plants both wild and domestic contain a vast reservoir of genetic variables that people have experimented with over the years to create and mold hop varieties to meet their brewing needs. Some very old varieties are still in circulation, while others have fallen by the wayside. New varieties are being developed all the time to meet the evolving tastes of the consumer, produce a higher yield, and resist diseases and insect pests. The researchers who planted the nascent New York State Agricultural Experiment Station hop yard had selected thirty varieties to plant and monitor. Their goal was to see how well they would grow in the upstate New York climate: Can they fight off disease? Are they vulnerable to any particular kind of insect? What are the best means of controlling these threats?

Since powdery mildew and downy mildew pose the most serious threat to hop plants the world over, Miller, standing in the hop yard and weathering a passing rain squall, advised the farmers huddled around him to plant only hop varieties with some resistance to these two fungal diseases and reeled off a handful of names: Cascade, Fuggle, Willamette, Chinook, Nugget, Centennial, Liberty, and Newport. Of course, we already had a thousand hop plants in the ground. I double-checked with Dieter on our lineup: Cascade, Centennial, Brewer’s Gold, Nugget, and Cluster. Three out of five; we were off to a good start.

Or so we thought. A couple of growing seasons later we found ourselves waging a war against downy mildew. In search of answers we traveled to Washington’s Yakima Valley to spend a day with Paul Matthews and Nicholi Pitra, research scientists at Hopsteiner, an international company that has been growing hops for 170 years. Matthews is tall and shambling, with graying sandy-brown hair. He dresses like a fisherman and perpetually has sunglasses hanging around his neck and safety glasses perched on top of his head. His slightly befuddled, senior scientist demeanor is offset by his sharp and sarcastic wit. He and his young colleague Pitra share an all-encompassing enthusiasm for food, drink, hops, and Yakima culture. Together they lead us on a whirlwind tour of Yakima that begins in a Hopsteiner laboratory and takes us through processing facilities and hundreds of acres of hop yards before stopping for libation at an on-farm brewery.

In his lab Matthews—with help from Pitra, another young scientist named Mark Coles, and their robotic sampling system—analyzes the DNA of more than fifteen thousand different hop plants a year. They are searching for what he calls “genetic outliers,” plants that he can cross to develop new hop varieties with such features as disease tolerance (that make them easier to grow), as well as particular qualities, such as a high percentage of alpha acids (that make them desirable for brewers).

In other words, the search goes on for the perfect blend of varieties. In the meantime, potential hop growers in Eastern regions can launch in by selecting from a few different categories of hops varieties—native hops, naturalized hops, heirloom hops, and modern hops.

NATIVE HOPS

The common hop used in brewing beer had its wild origins in Eurasia and spread through temperate regions around the world. But North America has its native variety of the hop, referred to as Humulus americanus. Native American tribes, including the Mohegans of Connecticut and the Menominee of Wisconsin and Michigan, used hops medicinally as a sedative; however, hops were not cultivated in North America until the arrival of the beer-drinking Europeans.

When the European colonists arrived in North America there were actually three varieties of native hops growing wild across the continent. In general Humulus lupulus var. lupuloides grew in the eastern part of the continent, Humulus lupulus var. pubescens in the Midwest, and Humulus lupulus var. neomexicanus in the West. The eastern Humulus lupulus var. lupuloides was the first to encounter and cross with hops imported from Europe, and eventually most of the wild hops followed suit, although work is now being done in New Mexico to bring back the native form of Humulus lupulus var. neomexicanus. To make matters more complicated, today’s plant geneticists are also finding characteristics of all three native varieties cropping up in hops found growing wild scattered all around the country.

NATURALIZED HOPS

Over centuries many varieties of hops developed around the world have been tailored to regional flavor preferences, and ancient and modern plant breeders alike have tinkered with varieties to create plants that can thrive in local microclimates. In some cases these regional varieties are no longer commercially grown, but individuals living in the region where they once were have continued to cultivate them as heirlooms in their yards or gardens. In other cases no one bothered to cultivate them, but the plants hung on, growing feral on farms, along road-sides or railroad tracks—perhaps crossing with other stray hops and creating new varieties in the process. Distinct from native hops or heirloom hops, these escaped domestic hops have naturalized over time, making adaptations unique to their regions as they reproduce. The growing desire to create and consume beer made with increasingly local ingredients has led some brewers on a quest to find varieties unique to their locality.

Because of hundreds of years of cross-pollination, it is very unlikely that hops found growing wild today in the eastern United States or elsewhere on the continent are truly native North American hops. Instead they are likely to be crossed with hop varieties once cultivated in the region in which they are found growing.

Dieter and his beer compatriot Craig Gravina, who writes a beer blog called Drink Drank and coauthored the book Upper Hudson Valley Beer, call foraging for hops “hop scrounging.” It’s not hard. Basically you just drive around backcountry roads looking for hops. The most likely place to find old hops is in overgrown areas that used to be farmland. They may be growing up collapsed farm buildings or near old foundations or found in abandoned orchards or growing up trees in overgrown farm fields. Hops can sometimes grow along railroad tracks that pass through areas once farmed and now overgrown. It was not uncommon for hop yards to be located near railroads, as hops were often transported to breweries by rail. Sometimes you are checking out previous sightings and sometimes you are just exploring. As far as I can see, it’s a good excuse to ramble about, then return home to drink beer.

The naturalized hops that hops hunters find are once-cultivated plants that, because they are untended, are being pollinated and going to seed free of the force of human selection. Their qualities have probably changed a great deal over time. Since they have survived, the changes will obviously have been advantageous for the particular environment in which they are found. But whether or not the changes they have undergone are good for beer remain unknown until someone tries brewing with them. However, foraging home brewers are generally a rugged bunch, and the only way for them to satisfy their curiosity is to do just that.

Once you find a naturalized hop, take a cutting or a rhizome and bring it home and propagate it. Keep a precise record of where you found it. When you plant it in the ground, make sure you keep it a good distance away from your other hops to avoid the possibility of contamination with disease, or possible pollination if it turns out to be a male. You can grow the hop to maturity, harvest the cones, then have them tested for their acid and essential oil levels and use the hops to brew an experimental batch of beer. If you are really interested in learning about the plant’s genetics, you can reach out to Cornell University or another research center and see if they are interested in testing the plant’s tissue to learn about its DNA. Our friend Andy Pelletier found a hop growing wild in his hometown of Bovina Center, New York, a place where hops were once grown commercially. We have submitted the plant for testing and are awaiting the DNA results. In the meantime he has planted the hop in his garden and during the summer trains it to grow around the top of his garden fence.

Home brewer David Warburton of Rensselaerville, New York, is now cultivating feral hops he found growing wild near his home. Collecting wild hops for cultivation is a fun and useful activity. Hop geneticists are interested in testing as many hops found growing wild as possible to learn about the genetic diversity of the plant.

HEIRLOOM HOPS

Another local friend, Dan Driscoll, is the original hop scrounger. With a lifelong keen interest in nature and history, Dan years ago obtained a number of cultivated hops being cared for by a retired farmer in the Helderberg region. The hops were what remained of a hop yard once cultivated by previous generations of the farmer’s family. Dan has been tending them for some thirty years. No spring chicken himself, Dan bequeathed a number of these “Helderberg hop” plants to Dieter, who is now cultivating them in a small hop yard adjacent to our barn. We are considering this an heirloom variety since it has been continuously cultivated—though in fact we have absolutely no idea what type of hop it is. Testing of the Helderberg hops’ alpha and beta acids has shown that they are akin to the hop variety called Cluster. The oldest hop variety in North America, Cluster itself is sometimes referred to as a landrace variety (meaning an old variety originating in a particular region to which it is uniquely adapted) because it is believed to be the result of crossbreeding between the wild hop Humulus americanus and varieties brought across the Atlantic Ocean by Dutch and English colonists.

The Helderberg hops did well their first year in the ground, in fact better than the various disease-resistant varieties we were growing in our other, larger hop yard. However, in the second year they seemed to take everything harder—from frost, to wind, to insect damage. They were hit hard by Japanese beetles, recovered, and put out new growth—only to be hit hard again. Hops are tough, hardy plants. They can survive just about anything. Although it is hard to kill the plant, it is just as hard to keep it healthy. The fact that even the Helderberg hop, which has been surviving one way or another in our region for probably one hundred years, can seriously struggle from time to time points out the need for a diverse selection in the hop yard.

MODERN HOPS

Fortunately, in the century since the hop yards in the Northeast were abandoned, hop growers in Europe and the Northwest have been hard at work applying new science and technology to develop varieties that have more resistance to disease and pests. Cultivated varieties of hops, as opposed to wild varieties, are referred to as “cultivars.” Hop breeders are constantly seeking to develop new varieties of hops that produce higher yields, have unique flavor qualities, are resistant to disease—and preferably all of the above. Hop breeders work with male and female plants to cross existing varieties through pollination, plant the seeds, and experiment with the results. It is a laborious process, taking up to ten years to produce results.

The Helderberg hops, left over from a commercial hop yard on a farm in the Helderberg region, were continuously cultivated by generations of a local farm family.

When Paul Matthews brought us through Hopsteiner’s challenge hop yard in the Yakima Valley, where trial varieties of hops are grown without the use of pesticides to see how they do, he pointed out a plant that might solve the fungus problems that brought us there: “Apollo is the one you want for downy mildew resistance,” he said. The challenge yard is tucked away in a 400-acre (162-hectare) hop yard operated by Golden Gate Emerald Hop Ranches in Sunnyside, Washington. Apollo, which Matthews calls “the most productive hop in the world,” was developed by the Hopsteiner breeding program. The new variety is now being cultivated in some commercial hop yards. Those growers have to spray it just once for downy mildew at the beginning of the season. Apollo was created in 2000 by cross-pollinating a female plant of the variety Zeus with a male plant known as 98001, whose mother was a Galena and father was a Nugget. Apollo was discovered among the numerous seedlings germinated in a lab from the cross, then screened in the field for key qualities. Other varieties developed by Hopsteiner include Lemon Drop, Super Galena, Delta, Bravo, and Calypso.

In the modern world, when plant breeders develop a new variety they often patent it with the United States Patent and Trademark Office. This means the breeder essentially owns the variety and people have to pay for the right to propagate it. Patented varieties are identified by the symbol ® appearing after the name, as in Amarillo® (VGXP01cv); Ahtanum® (YCR 1 cv); El Dorado®; Palisade® (YCR 4 cv); Warrior® (YCR 5 cv). The name is the registered name for marketing purposes. The letters and numbers that appear afterward are the variety’s official ID. This is because some varieties are marketed under more than one name. All this is unnecessary for nonpatented varieties, which are considered “public” and can be propagated, grown, and sold without restriction. Apollo was patented by Hopsteiner, and rhizomes of Apollo hops are available from Hopsteiner under contract in limited amounts.

Nicholi Pitra of Hopsteiner is quick to point out the difference between the type of plant breeding it is doing and the work being done to create genetically modified organisms (GMOs). “We do traditional plant breeding. We do not do genetic modification,” said Pitra. Techniques used to create GMOs alter a plant’s genome by adding genes not normally present to provide a plant with a particular trait. Traditional plant breeding, on the other hand, involves looking for genetic variations that already exist among plants and capitalizing on them through selected breeding.

Paul Matthews, senior research scientist at Hopsteiner. Matthews travels the world for Hopsteiner, sampling DNA from plants in a quest to develop new hop varieties with high alpha acids that are resistant to disease.

When the Hopsteiner team does its DNA analyses, the variations in the genetic sequences they identify are called single nucleotide polymorphisms or SNPS (pronounced snips). These SNPS function as molecular markers, highlighting exactly where the variation in genetic coding associated with a particular observed trait appears within the plant’s genetic sequence. Once identified, this marker allows plant breeders to zero in on the genetics for the trait they want to reproduce, allowing them to breed new varieties faster and more accurately. “Marker assisted selection takes about two years off the process,” explained Pitra. “It provides growers with sustainable varieties that need less spraying, helping them to reduce their environmental footprint.”

“Onion, garlic, guava,” Matthews called out as he walked down a row of hops, naming the aromas of the different varieties of hops he had planted in what he calls his “World Collection.” This is another one of Hopsteiner’s experimental plots, containing seven plants each of one hundred different hop varieties collected from around the world. The aromas Matthews named may seem like random associations but are in fact from a range of aroma standards developed for hops by the industry. For example, a bar chart in Apollo’s official aroma evaluation shows that it possesses a blend of citrus, spice, earth, and sugar aromas. Of course there are always individual variations. “Peach, mint, cinnamon,” he continued. “Some smell like cat piss. Some smell like marijuana, not that I’ve ever smelled that before.”

Nicholi Pitra examines a male hop plant growing at Hop-steiner in Yakima, Washington. Photograph by Laura Ten Eyck

Chinook hop samples in the Hopsteiner laboratory in Yakima. Photograph by Laura Ten Eyck

Matthews travels the globe to collect hop varieties both wild and cultivated in his search for building blocks to develop new hop varieties. He is seeking out many things, but foremost in his mind these days are traits such as high alpha acids—to help craft brewers make the uber-bitter beer that is taking the country by storm—and disease resistance. We are hoping his quest will result in hop varieties that allow growers in the East to withstand downy mildew.

There are many different varieties of hops, and commercial growers are continuously modifying the array of varieties they offer to brewers, planting newly developed varieties they think will meet emerging needs of the marketplace and phasing out varieties that fall out of favor or are replaced by something new that is easier to grow. The hobby grower has the luxury of using her personal taste and curiosity as a guide, yet there are so many options that a scattershot approach to choosing varieties can quickly result in an overwhelming number of plants. In the United States a handful of popular varieties has emerged as reliable and multiuse.

Hops in the challenge greenhouse at the Hopsteiner laboratory in Yakima being tested for powdery mildew resistance.

TABLE 2.1. Hop Varieties Recommended for the Northeast

Variety	Brewing Usage	Aroma Characteristics	Yield	Maturity
Brewer’s Gold	bittering	sharp, pungent, black current, fruit, spice	2,200 to 2,600 pounds per acre	late
Cascade	aroma	medium intense floral, citrus, grapefruit tones	1,800 to 2,200 pounds per acre	medium to medium late
Centennial	dual purpose	medium intense floral, citrus, lemon tones	1,430 to 1,700 pounds per acre	early to medium early
Fuggle	aroma	mild wood and fruit	1,000 to 1,400 pounds per acre	early
Liberty	aroma	mild yet spicy, subtle lemon, citrus tones	1,000 to 1,780 pounds per acre	medium early
Mount Hood	aroma	mild, herbal, somewhat pungent, spicy	1,250 to 1,960 pounds per acre	medium
Nugget	bittering	mild and pleasant, spicy, herbal tones	1,800 to 2,400 pounds per acre	medium late to late
Willamette	aroma	mild and pleasant, spicy, floral tones	1,700 to 2,200 pounds per acre	medium

Sources: Cornell University (for Northeast recommendations); Hopunion (for brewing usage and aroma characteristics); Oregon State University (for yield and maturity)