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).
Infected downy mildew spike. Photo: Ontario Hop Growers Association
Infected powdery mildew flag shoot. Photo: Plant Management Network.
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
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 firstname.lastname@example.org.
Introductory Hop Workshop
Friday, June 8, 4-6:30 pm
Plant Science Hall Room 199
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 email@example.com with questions.
Harvest Demonstration Workshop
Friday, August 17, Panhandle Research and Extension Center, Scottsbluff, NE
Friday, August 24, East Campus Hop Yard, Lincoln, NE
SAVE THE DATES!
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.
Questions? Please contact Katie at firstname.lastname@example.org or 402-472-3036. Keep up to date by subscribing to the hopextension listserv, and on Twitter and Facebook by following @UNLhops.