Update on Hop Variety Trials, Breeding

Clint Thompson Florida, Hops, Top Posts

By Zhanao Deng, Shinsuke Agehara, Hugh Smith, Gary Vallad, Johan Desaeger, Zhengfei Guan, Jack Rechcigl and Simon Bollin

Cascade is Florida’s top-performing hop variety with the highest annual cone yield.

In 2015, the University of Florida/Institute of Food and Agricultural Sciences (UF/IFAS) Gulf Coast Research and Education Center (GCREC) began field trials to grow hops in Central Florida. A research and Extension team consisting of approximately 20 faculty and staff members (Figure 1) was formed for this purpose. Initial trials the first three years encountered several challenges to growing hops, including poor plant growth, asynchronous flowering, low hop cone yield, protracted harvesting, etc.

By artificially extending the day length with LED lights, proper training of plants, timely management of plant nutrient and water needs, and integrated control of pests, the team has overcome these issues and routinely produced two crops of hops a year. In particular, day length extension has proven essential to hop production in Florida; it has worked reliably and consistently over four years.

All hop variety trials discussed below were conducted with LED lighting to extend day length to 16 hours and a simple 19-foot-tall vertical trellis system. These trials have been supported by the U.S. Department of Agriculture/Agriculture Marketing Service’s Specialty Crop Block Grant program through the Florida Department of Agriculture and Consumer Services Specialty Crop Block Grant, Hillsborough County Economic Development, local brewers, specialty crop industries and allies, the GCREC Innovation Seed Fund and GCREC faculty programs.

Trial Results

Over the last six years, the GCREC team has trialed 22 hop varieties in Central Florida. The varieties were bred in the United States and in Europe and have been commonly used by Florida craft brewers. These varieties have shown huge differences in plant growth and height, side arm (lateral) development, cone yield and cone quality.

Cascade remains the top performer with the highest cone yield on an annual basis (Figure 2). On average, Cascade sprouted by mid-February, with plants reaching the top of the trellis by mid or late April. After turning LED lights off in early May or late April, plants rapidly developed flower buds and bloomed within approximately three weeks.

Hop cones reached maturity by mid-June. After spring harvest, Cascade resprouted quickly and entered the second cropping cycle in the hot and humid July and August. By mid-November, the second crop (fall crop) was mature. Cascade produced an average of 2.01 pounds of fresh hop cones per hill in the spring of 2019, 2020 and 2021 and an average of 1.16 pounds of fresh hop cones per hill in the fall of 2019 and 2020.

With 15 feet row spacing and 3 feet in-row spacing, 968 hills can be planted in an acre. The estimated fresh hop cone yield per acre for Cascade is an average of 1,950 pounds from the spring crop and 1,120 pounds from the fall crop.

Two sources of Cascade planting stock (tissue culture liners) were planted at three densities (1, 2 or 3 liners per hill) in variety trials. Figure 3 shows no significant differences were observed between the two sources of planting stock (S1 = AgriStarts and S2 = Hopsteiner) or among the three planting densities (P1, P2 or P3). Nevertheless, planting at least two liners per hill to minimize the loss of plants in planted hills is recommended.

Ongoing studies have shown that optimizing the hop yard trellis design and horticultural practices can further increase the cone yield of Cascade in Florida.

Dried Cascade cones were provided to craft brewers in Florida to make multiple batches of beer. Brewers recognized differences between Florida-produced Cascade and those purchased from outside in bittering capacity and flavor profile. Florida Cascade tends to be more citrusy and milder. Such differences are also reflected in chemical analyses of hop cones, especially in alpha/beta acids ratios and essential oil profiles.

Three other hop varieties (Comet, Nugget and Zeus) have produced higher cone yields than many other varieties in the tests. They produce 1.49 pounds of fresh cones per hill per year, or 1,443 pounds per acre. These varieties may have the potential to produce more cones in Florida if the hop yard management schedules such as day length extension are adjusted to the growth habit and/or development stages of these varieties. Hop cones of these varieties had good aroma strength and lupulin quality brewers liked.

Breeding Efforts

All existing hop varieties are bred and selected in places far away from Florida, where the climatic conditions and hop production systems are different. Florida’s climate, seasonality and novel hop production system needs specifically selected new hop varieties. Hop varieties bred and selected in Florida may help Florida growers secure a niche spot in the domestic and global hop market. Novel varieties may also further allow brewers to create new styles of craft beer for consumers.

GCREC researchers are exploring several breeding approaches to develop new hop varieties and have selected new male and female hop lines out of seedlings from open-pollinated flowers. Two female lines have been identified that produce hop cones with strong aroma. Some male hop lines have been selected that may allow the creation of new crosses and new breeding populations.

A number of Cascade tetraploids have been induced; they produce larger and heavier cones with stronger aroma than the common diploid Cascade. These tetraploids may allow the development of new triploid hops that will not produce nuisance seeds in hop cones even if male hop plants and sources of viable pollen are present.

The researchers are particularly excited about several variant lines from Cascade that were recently identified. These variant Cascade lines produce large, long cones with strong aroma and high alpha acids and essential oil content. These new variant lines will be further tested in the next several years to assess their plant growth, resistance to root-knot nematodes, yield potential, cone quality, etc. A limited number of cones of these variants will be made available to local brewers for testing. The hop production system will be further optimized to maximize the yield of these lines. If things go well, new Florida-bred hop varieties may be available to Florida growers, brewers and consumers in five years.   

More Information

A series of articles on hops has been published by UF/IFAS researchers at the Ask IFAS website (http://edis.ifas.ufl.edu/). These articles cover a range of topics, from hop yard establishment to storing harvested hops. More information on hops grown at the GCREC is available on Facebook (facebook.com/UFHops/) and YouTube (youtube.com/channel/UCMyYAfFZsib6d4ZI-eaxCTQ).

Zhanao Deng is a professor, Shinsuke Agehara is an assistant professor, Gary Vallad is a professor, Hugh Smith is an associate professor, Johan Desaeger is an assistant professor, Zhengfei Guan in an associate professor, and Jack Rechcigl is center director and professor — all at the UF/IFAS GCREC in Wimauma. Simon Bollin is an agricultural business manager for Hillsborough County Economic Development in Tampa.