Spring Pruning Practices

In the spring in most hop yards, there are two pruning events. The first, which removes bull shoots, is done mechanically or chemically as a cultural means to reduce downy mildew (Pseudoperonospora humuli) and powdery mildew (Podosphaera macularis) inoculum. Initial shoots are also undesirable due to irregular growth rates and are generally weaker than shoots that come later. These two foliar diseases are the most significant diseases of hops in the state of Nebraska, as well as other hop growing regions in the U.S.

Hops have a perennial crown with buds that overwinter on both established and new wood, and both diseases have the capability to survive winter on the buds that will produce shoots in the spring. The first shoots in the spring, if infected, will provide initial inoculum for the season. Downy mildew spikes appear bright green, stunted, and leaves curled (left photo below). Powdery mildew flag shoots appear stunted, and covered in powdery white colonies (right photo below).

The initial pruning has been shown to reduce the amount of mildew presence in hop yards and to reduce fungicide applications in the Pacific Northwest United States. You can read more about the scientific study in the American Phytopathological Society Journal here. Pruning can be done mechanically, removing everything from the soil surface to 1″ below the soil surface; can be conducted chemically (although only pruning chemically too early has not shown positive results in reducing diseased shoots); or a combination of both (recommended). If pruning chemically, Aim or Scythe are products registered for use on hops in Nebraska. While not as common, using a propane flame is another option. The more thorough the pruning, the better control of initial disease inoculum. Initial pruning can be done when shoots are 3-10″ tall. It is important to keep records of these pruning events, because each year is different.

In regions of longer growing seasons, such as the Pacific Northwest and here in Nebraska, a second spring pruning event is recommended, as pruning date determines training date, which ultimately determines plant yield. The purpose of the second pruning is to time shoot growth appropriately with plant vigor to reach maximum yields. This spring, I will be conducting a pruning trial to help us better understand what dates will help regional growers reach their optimum yield. Since ideal timing for the second pruning has not been fully determined for this region, it is best to keep records. Training, depending on variety, is done in May, when bines are approximately 2′ tall.


A note of caution as you plan out your season and consider chemicals to control weeds and pests and diseases:

First and foremost, you should check to see if the product you wish to use is labeled specifically for hops in Nebraska. Each state is different. You can check using the Nebraska Department of Agriculture website here. Keep it bookmarked – it will come in handy! Secondly, salesmen in Nebraska are able, and will try, to sell you products that are not labeled for hops in the state. Do your research before you purchase anything. Spraying products not labeled for hops in Nebraska could later prevent you from selling your hops in the fall. (You can feel free to reach out to me or to the UNL Pesticide Safety Education Program. They can help with certification for pesticide applicators – a certification you should have if applying chemicals.) Next, once you have acquired a legal product, carefully follow the label for directions, or if applying to banded acres, use the calculations below.

Treated Acres versus Sprayed Acres: When planning applications of any herbicide, one should refer to the label before taking any action. Generally, application rates are listed on labels as pounds, pints, or quarts per acre. Most herbicides are applied over the hop rows, otherwise known as banded applications. Calculating the correct amount for a banded applications is important for your hops. There are 43,560 square feet in one acre. In a 1 acre hop yard with 14 feet between rows, there are 3,111 feet of row (43,560/14). Bands are approximately 4 feet wide, resulting in 12,444 square feet or 0.28 acre of area to treat (3,111 x 4). Following the label without calculating banded applications could result in much higher concentrations of herbicide being applied, and therefore causing severe damage to your hop plants.
Steps to Calculate Banded Rates1
1. Divide total square feet of one acre by row spacing in feet to determine feet of row per acre. (43,560/14 = 3,111 ft)
2. Multiply the feet of row per acre by the band width in your hop yard to determine the square footage to be treated. (3,111 ft x 4 ft = 12,444 sq ft
3. Divide treated area by area of one acre to calculate the percentage of one acre to treat. (12,444/43,560 = 0.28 = 28%
4. Multiply the percentage of acre to be treated by the label broadcast rate (in this example, 1 pound). 0.28 x 1 pound = 0.28 pounds
5. Multiply the percentage of acre to be treated by the recommended volume of water for an acre to determine the amount of water to use per acre. 0.28 x 30 gallons = 8.4 gallons
1. ID-462-W – Hops Production in Indiana, Integrated Pest Management Guide for Hops in Indiana 2015

Finally, keep detailed records of all chemical applications made as this is important when you sell your final products in the fall.


Upcoming spring and summer workshops & events:

Weed & Fertility Management Workshop

Friday, April 6, 4-6 pm
Plant Science Hall Room 199 
Cost: Free
This workshop will include educational information on managing hop yard weeds, soil and plant fertility, and hands-on development of a fertility plan for hop production. Attendees will receive a list of pre and post emergent herbicides labeled in Nebraska for hops. A campus hop yard tour will be held following presentations, weather permitting. For questions or to register, please email katie.kreuser@unl.edu.

Introductory Hop Workshop

Friday, June 8, 4-6:30 pm
Plant Science Hall Room 199 
Cost: $10
This workshop will provide information on the cost of hop production, trellis design and set up, and basic information on hop agronomics, harvest, and post-harvest processing. A local brewer will be on hand to discuss what they are looking for in locally produced hops for their beers. Check back soon for registration details. Please email katie.kreuser@unl.edu with questions.

Harvest Demonstration Workshop 

Friday, August 17, Panhandle Research and Extension Center, Scottsbluff, NE

Friday, August 24, East Campus Hop Yard, Lincoln, NE


Summer Hop Yard Tours & Field Days with Nebraska Hop Growers Association

Saturday, June 2 – Homestead Hops

Saturday, July 21 – Oak Creek Hops & Thunderhead Brewing Co., Kearney, NE

Saturday, August 4 – 6th Meridian Hops and South Dakota Hops Growers & Malters, Yankton, SD – this will be a full day of education presentations, hands on demonstrations, beer tasting and food available for purchase provided by a local food truck.

hop bullet

Questions? Please contact Katie at katie.kreuser@unl.edu or 402-472-3036. Keep up to date by subscribing to the hopextension listserv, and on Twitter and Facebook by following @UNLhops. 


Spring Management in the Hop Yard

It’s hard to believe that it’s finally time to start walking your hop yards to check for signs of spring. The snow is melting and temperatures are warming. I walked the campus hop yard yesterday. Spring buds are forming around the crowns and weeds are greening up. (Speaking of weeds — have you signed up for the weed and fertility management workshop? See more details here.) As spring approaches, consider the following management activities to adequately prepare you for the growing season.

  • Clean and disinfect your equipment and tools. Removing any remnants of plant material or soil from your toils, and wiping them down with a 10% bleach or alcohol solution helps to prevent future infections.
  • Check your trellis and irrigation system. Check the trellis system by tightening any cable or anchors and checking poles for sturdiness to ensure the system can support the heavy bines later in the season. Check the drip system for any rodent damage, and run water to make sure it’s reaching all the emitters.
  • Clean up debris. Remove any debris from last season that may serve as host to pests and diseases.
  • Test your soils. If you did not test your soils last fall, now is a good time to test soils. Results provide what nutrients are currently in the soil and help to determine what you as a grower will need to add throughout the growing season.
  • Arrange coir shipment. If you haven’t already, arrange for your coir twine shipment. Soak the coir for 24 hours before stringing to help make tying an easier task. As the coir drys, it will constrict to prevent sliding on the cable.
  • Remove early hop shoots. Removal of early hop shoots is different than pruning in order to determine the correct training date. This first removal takes care of downy mildew shoots emerging from the crown as well as the hollow and more brittle shoots that typically emerge first. A later pruning will determine when to train the bines up the coir.

At this time, weeds have already emerged so the window for applying most pre-emergent herbicides has passed. Those should be applied in January or February when the plants are completely dormant. Based on the weeds spotted yesterday, careful spot spraying (on the rare occasion when it’s not windy) or hand pulling will suffice.

Weeds and early shoots emerge as weather warms at the East Campus Hop Yard on February 27, 2018.

Weeds and early shoots emerge as weather warms at the East Campus Hop Yard on February 27, 2018.


  • Hops Production Workshop, hosted by Midwest Hop ProducersSaturday, March 10, 2018, 8 am – 5 pm

    Southeast Community College, 537 Main Street, Plattsmouth, NE 68048. 

    For more information and to register, visit here.


  • Weed & Fertility Management Workshop

Friday, April 6, 4-6 pm
Plant Science Hall Room 199
Cost: Free
This workshop will include educational information on managing hop yard weeds, soil and plant fertility, and hands-on development of a fertility plan for hop production. A campus hop yard tour will be held following presentations, weather permitting. For questions or to register, please email katie.kreuser@unl.edu.


This summer, I’m partnering with the Nebraska Hop Growers Association, and a few of our state’s hop growers to host informal tours, educational sessions, and opportunities to network. These events will be free. In the case of meals being available, attendees will be responsible.

  • June Hop Yard TourSaturday, June 2, Homestead Hops, Utica, NE, Hop Yard Tour, Growing season update, light breakfast provided.
  • July Hop Yard TourSaturday, July 14, Kearney, Hop Yard Tour, Pest & Disease Update, lunch and meet the brewer at Thunderhead Brewing Company.
  • August Hop Yard TourTBD – Stay Tuned!


  • Introductory Hop Workshop

Friday, June 8, 4-6:30 pm
Plant Science Hall Room 199
Cost: $10
This workshop will provide information on the cost of hop production, trellis design and set up, and basic information on hop agronomics, harvest, and post-harvest processing. A local brewer will be on hand to discuss what they are looking for in locally produced hops for their beers. Check back soon for registration details. Please email katie.kreuser@unl.edu with questions.

Step 1. Marketing your hops

Pursuing hop production is a hot topic. Craft beer enthusiasts want more than just craft beer made locally. They seek out regional craft beer made with locally-grown ingredients. And while our climate, latitude, and soils make growing hops conducive, it’s not an easy undertaking. One of the most challenging parts about hops production doesn’t even involve the physical growing part of production. It’s the marketing aspect. It’s befriending and building relationships with brewers, giving away or testing out your hops in the first one or two years, and proving that you know your product and can produce a high quality product for their brewing needs. It’s a serious part of hop production that I’d encourage you to consider before putting any plants in the ground.

This past Saturday, the Nebraska Hop Growers Association (NHGA) held their annual meeting at Blue Blood Brewing Company in Lincoln, Nebraska. Their owner and founder, and member of the NHGA board of directors, Brian Podwinski spoke from a brewer’s perspective on working with regional hop growers and purchasing local hops.

As a brewer, he tries to incorporate as many locally sources ingredients as he can. What he prioritizes in making ingredient purchases is the quality and quantity of the product. With the majority of U.S. hop production happening in the Pacific Northwest, and more recently in Michigan, the scale of production has allowed them to produce high quality hops at lower costs. However, Nebraska brewers, like Brian, understand that Nebraska grown hops come at a premium (within reason), and are willing to work with growers because their customers like Nebraska-grown hops in their beer.

For brewers, quality doesn’t necessarily mean pelleted hops, though that is what the majority of brewers prefer to use in the brewing process. (One of the main reasons for preferring pelleted hops over whole cone is because the alpha acids in pelleted hops can be fully isomerized in the boil. It essentially utilizes the entire hop.) Quality means keeping spray records and following label instructions carefully to prevent residues in brewers’ beers. Quality means taking the necessary efforts to maintain color and prevent disease presence on or in the cones as the mature and ready for harvest. Quality is properly drying the cones to the correct moisture content and storing them in mylar bags to prevent any light of moisture from entering and causing degradation and mold. Quality is reaching the alpha and beta acid target levels and storing hops at the proper Hop Storage Index (HSI). (HSI is a value given when cone samples are submitted for alpha and beta acid testing.)

Once you believe you’ve taken the correct steps in producing quality hops, Brian encourages growers to reach out to him about doing test batches in his pilot system. Ideally, you brew with your own hops and know exactly what you’re selling. Not all growers and brewers have a small brewing system, but brewers do expect you to know your own product. Learn what your hops should smell like and taste like in beer. The more you know your product, the easier it is to sell that said product.


As we amp up for the 2018 growing season, we have a few workshops coming up and some other exciting events so stay tuned for more details.

  1. Weed Management & Fertility Workshop. Friday, April 6, 2018, 4-6:00 pm. East Campus, Plant Science Hall Room 199. Topics to be covered include management of weeds in your hop yard, fertility of hops, and how to develop a fertility plan for your yard. Email katie.kreuser@unl.edu or call 402-472-3036 to register.
  2. Introduction to Hop Production Workshop. Friday, June 8, 2018, 4-6:30 pm. East Campus, Plant Science Hall Room 199. Topics to be covered include hop production costs, trellis design and set up,  and basic information on hop agronomics, harvest, and post-harvest processing. We’re excited to have a local brewer join us to share more of their perspective on working with local hop producers. Registration details will follow.

Stay tuned for First Saturday Hop Yard tours! UNL Hops will be partnering with the Nebraska Hop Growers Association to tour a few hops yards across the state this summer. We will incorporate hands on scouting and integrated pest management with these events. Plan to join us bright and early on a few Saturday mornings over coffee, light breakfast and hop yard tours. I’d like to plan to have at least one event in the central part of Nebraska. Tentative dates: May 5, June 2, and July 14 (postponed later due to July 4 holiday). If you are a grower and interested in hosting, please contact Katie at katie.kreuser@unl.edu or 402-472-3036. The only obligation is allowing visitors in your hop yard. These events will be limited to 20 people. 

Nebraska Grower and Brewer Conference & More

January has been a whirlwind!

First of all, thank you for all those that attended the 2nd annual Nebraska Grower and Brewer Conference & Trade Show. We had 212 total attendees, including speakers and vendors, some excellent presentations and opportunities to network and learn from one another. I’ve heard great feedback from many, however, if you have not taken the survey yet, please do so here.

A few comments I’d like to reiterate from the conference:

Community – Relationships move this industry forward. As hop growers, other growers are not your competition. Estimates for acreage to meet the state and region’s hop demand are far from the current acreage. Success isn’t going to come from every man working on his own. Knowledge in the industry should be shared, and aspects of hop production and craft brewing should be combined.

Quality – More specifically, with demand for the hop end product being primarily pelleted hops, forming cooperatives that provide pelleting services for regional growers reduces heavy up front costs for equipment that isn’t heavily used year-round and offers flexibility for participants. Sharing harvesting and other equipment if timing works are also options.

As a state, our focus should be to produce consistent, high quality hops that brewers can count on for their beers. Moving forward, the Nebraska Hop Growers Association and the Nebraska Craft Brewers Guild, along with the University, will work together to provide information on brewer expectations in the form of guidelines to better meet this goal of consistent hop quality. This would increase your marketing efforts as growers backed by verified organizations. An excellent example that could serve as a resource in the meantime is here.

I am excited for the progress in the industry. You as growers have put much sweat, tears and hard work into it this far. Let’s keep going! Our plants will be emerging from the ground soon. I’ll be sharing updates here regularly as we plan and announce workshops and trainings, watch plants progress throughout the season, and prepare for another delicious harvest.


Last week I had the opportunity to attend the American Hop Convention. The panel discussions, networking, educational and market report sessions were invaluable listen to and observe.

The hops market, as with most agriculture crops, is cyclical, and with recent years predictions in significant craft beer growth, acreage has expanded significantly in the Pacific Northwest, 19% in 2017to be exact. In 2017, however, craft beer is still growing but at a slower than predicted pace, cuing hop storage build up at many of the hop merchants in the PNW. A smaller than predicted shortage in Europe was reported after rains before harvest helped to recover some of the anticipated hop shortage, reducing as much need from the USA for hops. Production increased 19.8% in total million pounds between 2016 and 2017, bringing 2017’s total to 106.2 MM pounds.

How does this effect hop growers in Nebraska? Surpluses of varieties like cascade in hop merchants warehouses allow them to lower prices significantly to ranges that aren’t feasible for growers on a small scale. Unless a brewer specifically wants Nebraska-grown cascade (thinking terroir here), selling cascade as whole cone or pelleted hops will be cost prohibitive. This is bad news for Nebraska growers, many of which have cascade on hand.

This highlights the dire importance of beginning with marketing as you pursue hop growing, and the risk growers take with swings in the market. Speaking specifically with brewers, building relationships with them, and proving you can produce a quality hop product must all happen before any purchases are made. If you want a piece of the market, a quality product is how to compete.

Now, it’s not all doom and gloom. Exciting things happening in the industry include Michigan intending to become the next state member of the USA Hop Growers Association this year. Outside of Washington, Oregon and Idaho, they’ll be the 4th member, having only begun in the industry in 2007-2008. Today, the state has over 800 (and growing) acres of hops, a vibrant state Growers Association, and most recently had a farm (Hop Head Farms) come in 4th place in the cascade cup, a hop quality competition organized by the Hop Quality Group.

Nebraska represented at the conference, which is a great way to make the industry aware of areas outside of the traditional growing region. We can share what’s happening in the state, learn best practices and new innovations to apply at home, and build connections that lead to future collaborations.


I will continue to monitor the market and communicate current events. We have a weeding and fertility workshop planned for late March/early February that we’ll announce in the next couple of weeks. We will again host an introductory hop production workshop, and two harvest workshops in August – one in Lincoln and one in Scottsbluff.

The Nebraska Hop Growers Association 2018 annual meeting will be held on Saturday, February 10th, 1-4 pm at Blue Blood Brewing Company, 925 Robbers Cave Rd, Lincoln, NE 68502. Voting members (commercial growers) should be present from 1-3 pm. All members will meet following at 3 pm on. The focus of the member meeting will be hop quality through post-harvest processing, and desired hop quality for brewers. Interested in joining? Visit their website here. I hope to see you there.

If Extension can be of help to you, reach out to katie.kreuser@unl.edu or call 402-472-3036. Cheers to the 2018 growing season!



FSMA Produce Safety Rule & Hops

The Food Safety Modernization Act (FSMA), a law signed in 2011, provides major changes to food safety laws in the United States. Depending on the size of your farm, compliance dates are as early as January 2018. The law’s Produce Safety Rule (PSR) covers a wide variety of produce, including hops. Today, I will address what you need to know as a hop grower going forward. I am also excited to welcome Dr. Connie Fisk, our regional expert on food safety, to speak at the Nebraska Grower and Brewer Conference in January.

According to the rule, hops are not included in the “rarely consumed raw” category. The rule states:

We are aware that hops are regularly added to beer after all cook steps are completed in a process known as “dry hopping” (Ref. 90). Therefore it would not be reasonable to infer on this basis that hops were not consumed uncooked in any measurable quantity by most consumers across the United States, and we are not adding hops to the list of rarely consumed raw produce. Instead, hops are covered produce subject to the requirements of part 112 as applicable. However, we note that hops used in the making of beer will be eligible for exemption from the requirements of part 112 under the provisions of § 112.2(b)(1), provided the covered farm establishes and maintains documentation in accordance with § 112.2(b)(2).

So as a hop grower, what do you need to do?

If you averaged more than $25,000 revenue from hops in the past three years, you need to take the following steps:

  1. Determine whether the hops sold were used in the brewing process or “dry hopping.”
  2. If the majority of the hops were or will be brewed (not used for dry-hopping), request a letter from the purchasers that includes information on the processes the hops will undergo and details of how the pathogens will be killed, such as fermenting or cooking).

If you average more than $25,000 revenue from hops and the majority were used in the dry-hopping process, your farm is covered under the FSMA Produce Safety Rule. This requires that you adopt the Produce Safety Rule.

Any farm covered under the Produce Safety Rule will need to send a single employee to Produce Safety Alliance (PSA) Training. Once training is complete, you are eligible for an On Farm Readiness Review. When a farm is ready, a review gives growers the chance to apply the rule, and learn about how to be compliant. Check here for upcoming training opportunities.

Additionally for ALL growers, two steps should be taken:

  1. The bill of lading, invoice and/or the unit of sale has to have the words, “not processed to adequately reduce the presence of microorganisms of public health significance” on it.
  2. The person who bought it needs to provide proof that they actually used it in the making of beer.  That can be a letter, but it needs to be written and kept by the seller. (Refer to step #2 above).


Implementation Dates 

Implementation dates are based on total produce sales from an individual farm.

Large business: earned more than $500,000 in average produce sales in the past 3 years. Compliance date: January 26, 2018.

Small business: earned between $250,000 and $500,000 in average produce sales in the past 3 years. Compliance date: January 28, 2019.

Very small business: earned between $25,000 and $250,000 in average produce sales in the past 3 years. Compliance date: January 27, 2020.

Even if you are not required to be in compliance immediately, you should begin to take the necessary steps to begin implementation. The hops market is still a very small market in the region and we should do what we can to prevent anything from ruining it.

hop bullet

If you have questions, contact Katie Kreuser, Hop Program Coordinator, by phone, 402.472.3036, or by email, katie.kreuser@unl.edu.

Hop Viruses

Viruses have become an increasingly greater concern in Nebraska, where new hop yards are being established frequently. Whether you’re a new grower or interested in growing hops, or a seasoned grower needing to refresh virus management protocols, anyone involved in growing hops will find this post relevant.

There are three carlaviruses that infect hop plants: American hop latent virus, Hop latent virus, and Hop mosaic virus. Another potentially problematic virus that infects hops, and that will be discussed in this post, is the Hop stunt viroid. The difference between a virus and a viroid is the variations in their genetic and protein makeup.

The one most likely to inflict damage is the Hop mosaic virus. The main reason for concern besides a virus’ ease of spread is their ability to reduce the growth of infected plants. Yard establishment and yields are affected, generally reducing yields by 15%, however, some varieties have shown a reduction of up to 62%. While growth is jeopardized, the good news is that changes in brewing characteristics of the cones seems to be minimal in general.

Viruses are spread through propagation, root grafting or through agronomic management practices such as pruning in the hop yard. Infected plant material is the most common form of spreading over distances. Aphids have the ability to transmit viruses from feeding on plants, though it doesn’t happen reliably. While aphid control through spraying may seem like an option for controlling the virus spread, it likely only cuts back on secondary transmission.

Due to carlaviruses having a minimal host range, concern for other hosts are, for the most part, only other hop plants in a yard.

The most practiced method of virus prevention in the hop yard is sourcing certified disease and virus free plant material. See more from the previous post here.

Apple Mosaic Virus

Apple mosaic virus is the most serious of the carlavirus diseases to affect hop plants.

The virus commonly appears on hop leaves as necrotic rings or arcs, which sometimes become oak-leaf like patterns. Severity of symptoms depends on weather patterns. Typically they worsen when periods of cool weather are followed by periods with high temperatures. In many cases, symptoms do not appear, until the right environmental conditions acerbate the plant, meaning the infected plant could be in the yard for years without knowing. When extremely severe outbreaks occur, cones and their alpha acid content can be damaged. When weather conducive for infections to occur is not present, infections may remain unknown due to symptoms not being present. Multiple viruses can infect plants increasing infection severity.

Since infections of Apple mosaic virus aren’t detectable by the human eye when symptoms aren’t present, spread of the virus can also go undetected. The importance of regularly testing propagated material for virus presence, and purchasing certified disease and virus-free plants is important for this reason.

The rapidity of spread depends on the variety, protocols of propagators, and environmental conditions. There are no known insect vectors of Apple mosaic virus.

Managing infected yards begins with sourcing clean plants. When it comes to pruning to set your spring training date, the use of contact herbicides is best. If tools must be utilized for spring pruning, tools should be cleaned aggressively between each plant. General best practices recommend soaking tools in a 10% bleach solution for a 10 minute period. (Note that results have been inconsistent with this method.) If you suspect virus presence, plants should be tested immediately. As a general rule of thumb, if more than 10% of plants in a hop yard are infected, the entire yard should be replanted; if the infections are present on less than 10% of plants, individual plants should be culled.

Hop plants can be a challenge to cull. In late summer, cutting the infected plant at the base and painting the top of the crown with concentrated glyphosate should kill the plant, including the roots. On some occasions, multiple applications may be necessary.

Apple mosaic virus Take Home Notes:

  • When establishing a new hop yard, use certified virus-free plant material.
  • Use contact herbicides for spring pruning to remove basal growth and prevent virus transmission.

Hop stunt viroid

This serious hop disease is capable of alpha-acid content of cones of infected plants by 60-80%. Like the Apple mosaic virus, symptoms of Hop stunt viroid are affected by the variety of hop and the weather. In some cases, the presence of the virus went undetected for five years, enabling the spread of the virus through infected plant material. Common symptoms are visible in stunted bines in early spring that appear pale in color in comparison to healthy bines. In periods of rapid growth, internodes are shortened in virus presence, by as much as two-thirds. Wamer weather reflects more severity in symptoms. As the season progresses, infected plants are inhibited from producing lateral branches. This results in small and sparsely produced hop cones, that are developmentally delayed. Lower leaves remain pale in color throughout the growing season. The yellow speckling symptom of Apple mosaic virus has also been present, and could be a result of multiple virus infections on one plant.

Research has shown the Hop stunt viroid spreads through propagation and mechanical means. No evidence exists to suggest it is transmitted by seed or insect vectors. Once established, the primary mode of spread is through agronomic practices via tools or equipment used in pruning, thinning or leaf stripping. In the spring, hop plants have higher sap levels aiding in the virus’ transmission.

The best form of management of any virus, including Hop stunt viroidis beginning with clean plant material. Proper removal procedures should be followed for virus infections on a small number of plants in a hop yard, including the removal of roots. Due to the delay in symptoms, it is often recommended to remove a few plants on either side of infected plants in the same row as a preventative measure. In late summer, cutting the infected plant at the base and painting the top of the crown with concentrated glyphosate should kill the plant, including the roots. Areas where plants are killed should be left fallow for one season in case new shoots emerge for a second treatment. For larger infections, growers should consider soil fumigation as well.

The generally recommended practices for virus management should be followed for Hop stunt viroid as well.

Hop stunt viroid Take Home Notes:

  • When establishing a new hop yard, use certified virus-free plant material.
  • Remove any small number of infected plants to prevent further spread.
  • Use contact herbicides for spring pruning to remove basal growth and prevent virus transmission.
  • If replanting, remove any volunteer hop plants.
  • Aggressively and thoroughly wash all farm equipment.
  • Disinfection of tools between plants may prevent further spread. (10% bleach solution for 10 minutes.)

Clean Plant Sources

While the topic of today’s blog is crucial to those seriously considering establishing hop yards, it is also an important discussion for current growers. Disease prevention in our hop yards and greenhouses begin with sourcing clean plant material. The spread of viruses, powdery and downy mildew, insect pests such as Japanese beetles, and other pests through plant material occurs too often. When you can simply purchase hops on google and amazon, I cannot stress enough to proceed with caution. In fact, the only source I can fully endorse is the Clean Plant Network which propagates certified disease-free material. You can read more from their website here. When making efforts to establish a proper trellis system and proper irrigation, why not begin with clean plants too? Set yourself up for success from the beginning.

Diseases such as downy mildew are well established in the eastern portion of Nebraska. Beginning with clean plant material provides growers a clean slate with which to begin. That being said, a pest management plan and program should be in place to prevent future infections. Since brewer demand determines varieties to produce, growers should especially be prepared for preventative action on more susceptible varieties. As research continues to develop in this new industry for Nebraska, we hope new variety development will address some of the disease challenges.

If you have concerns that you have infected material, you may submit it to the UNL Plant and Pest Diagnostic Clinic for testing. They are currently setting up services to include virus testing. You can read more about sample submission here.

[I’ll be covering hop viruses in the next post. Stay tuned.]


What disease challenges have you had this season? What further information can I provide you with that will help to further your success as a hop grower?