Michigan hop crop report for the week of Sept. 6, 2021

Hop harvest is underway across Michigan.

Hops being harvested.
Hop harvest in east central Michigan on Aug. 21, 2021. Photos by Sean Trowbridge


Last week offered a hint of our seasonal change with much cooler temperatures than the previous week. Last week was also wetter than normal. Looking back on the growing season, we began the year very dry, with several inches of deficit. We now have major surpluses across much of the state. Soil moisture levels (plant extractable water in top 3 feet) are slightly above normal across much of the state.

In terms of degree day totals, most areas of the state are still in surplus (7-10 calendar days), going back to beginning of March. It looks like these surpluses will continue based on the 6-10 day outlook.

Degree day summary
Accumulated degree day base 50 summary for hop producing areas of Michigan on Sept. 7, 2021, as compared to the five-year average. Data source: MSU Enviroweather. 
Rainfall summary
Accumulated rainfall summary for hop producing areas of Michigan on Sept. 7, 2021, as compared to the five-year average. Data source: MSU Enviroewather.
Hawks Enviroweather
Monthly growing season rainfall totals for 2018-2021 illustrate some unusual rainfall patterns in 2020 and 2021. Figure by Rob Sirrine from MSU Enviroweather data.
Williamsburg Enviroweather graph
Monthly growing season rainfall totals for 2018-2021 illustrate some unusual rainfall patterns in 2020 and 2021. Figure by Rob Sirrine from MSU Enviroweather data.

A major storm system rolled through northwest Michigan Tuesday morning. Some areas experienced 60 mph winds and hail. For those who haven’t harvested, this system may have reduced yields, which were already depressed from recent storms.

Hops blown down the wire.
Wind damage in a northern Michigan hopyard, Aug. 26, 2021. Photo by Rob Sirrine, MSU Extension.
Wind damage to hop.
Wind damage in a northern Michigan hopyard, Aug. 26, 2021. Photo by Rob Sirrine, MSU Extension.

There is a 30-40% chance of showers Wednesday and Thursday across most of the state, with cooler than normal temperatures. Friday and Saturday are shaping up to be very pleasant prior to an increasing chance of rain early next week. Looking ahead, the 6-10 day outlook (Sept. 12-16, 2021) suggests above normal temperatures and average precipitation across the entire state.

Photo 7. 610temp.new 9-9
NOAA 6-10 day outlook, Sept. 12-16, 2021: Temperature probability.
Photo 8. 610prcp.new 9-9
NOAA 6-10 day outlook, Sept. 12-16, 2021: Precipitation probability.

Watch the most recent agricultural weather forecast from Michigan State University state climatologist Jeff Andresen.

Stage of production/physiology

Most hops across the state are in Principal Growth Stage 8: Maturity of Cones. For those interested in determining optimum harvest date, refer to these Michigan State University Extension and University of Vermont articles:

Average Michigan hop growth stage chart.

Average Michigan hop growth stage based on date. Botanical drawings courtesy of Dodds, Kevin. 2017. Hops, a guide for new growers. NSW Department of Primary Industries.
Timing of hop production management activities in northwest Michigan.

Hop stage

Pest management

With harvest imminent, underway, or in some cases over, pest management really slows down at this time of the season. Due to the limited winter survival or transient nature of many primary hop insect pests, postharvest management is not likely to substantially impact insect pest pressure next year. Additionally, postharvest treatments for mildews have not been shown to significantly reduce disease severity the following season when compared to traditional practices like spring pruning, protectant fungicides and foliage management.

Looking ahead, consider the importance of sanitation at this time. Removing all bines and leaves from the hopyard after the first hard freeze is an important sanitation practice. Plant tissues can harbor insects and disease and should be removed, fully composted, buried or burned. If you did not harvest this year (as in first year hops), remove aerial plant parts after a hard frost to prevent insect and disease carryover into next season. As we move into late fall and early winter and plants are dormant, growers might also consider applying herbicides for perennial weed control and removing unproductive or diseased crowns.

Irrigation system maintenance and water testing

If you are dealing with irrigation water issues like iron, algae or mineral build-up, periodic irrigation line cleaning is recommended. Consult with irrigation experts to ensure the proper treatment since some treatments may work well but have negative effects—for example, chlorine can kill beneficial soil microorganisms and sulfur can increase salt levels in the soil. Products like “Line Blaster” can be used a few times throughout the season as a preventative to keep emitters open. Filters at the pump station should be cleaned often; pressure gauges before and after the filter will indicate when a filter needs to be cleaned. Drain or blow out the irrigation system at the end of each growing season.

Even if you don’t experience any water issues, it is important to submit a water sample for a full water analysis. Results of a full water analysis can help you address many water quality issues ahead of time. For example, hard water may reduce fertilizer use efficiency and create potential problems when mixing pesticides. Proper maintenance will improve crop production and lengthen the life of your system. Two excellent irrigation presentations can be found on the Great Lakes Hop and Barley Conference Previous Conferences page under 2017 Conference Presentations.

For more information on irrigation, contact Lyndon Kelley, Michigan State University Extension irrigation specialist, at kelleyl@msu.edu

Winterizing on the farm

As temperatures drop, broken pipes from freeze damage and electrical equipment failure can result from poor winter preparation of irrigation equipment. Kelley recommends spending time now on your irrigation equipment to help avoid irrigation start-up repairs and delays next spring. Trickle, drip lines and tape are designed to be self-draining, but manifolds and supply systems need attention to make sure no water pockets remain to freeze. Winter rodent damage can turn drip tape and trickle line into junk rapidly. Lines that are to be moved for next year are best stored in the barn. Lines overwintering in the field stand less rodent damage if not covered by plastic, plant material or mulch.

Now is also a good time to inspect each electrical box in the system for damage and holes that may be accessible for rodents. Sealing small holes helps keep rodent damage to a minimum. Both snakes and mice have even been known to crawl into electrical boxes and control panels through small hole or underground conduit with unprotected ends resulting in electrical fire and damage.

Locking down electrical power supplies helps prevent vandals from turning wells and pivots on midwinter and minimizes potential electrical system damage. Now is an excellent time to inspect grounding, system test resistance and make repairs.

To learn more about winterizing your irrigation system, refer to the MSU Extension news article, “Protecting irrigation equipment from winter damage.”

Fall soil testing

Soil testing is a critical step in achieving the desired agronomic, economic and environmental outcomes from fertilizer practices. According to MSU Extension soils experts, there are several advantages to testing your soil in the fall. There is more time available in the fall to collect soil samples and make fertilizer decisions compared to spring. Fall weather conditions are typically more favorable for collecting soil samples. Michigan’s unpredictable spring weather conditions can force postponement or even abandonment of soil testing.

If yards require using soil acidifying applications of sulfur, fall applications can take advantage of frost heave and snowmelt to move sulfur into the soil and affect the pH and nutrient availability before bines begin growing again in the spring. Growers may also apply compost fertilizer in the fall and sub-soil between rows in areas in need of better drainage. It is recommended to closely follow the soil sampling protocol (depth, amount, # samples, etc.) provided by soil testing labs. To learn more about soil fertility and soil testing please refer to the Western Labs Presentation from the 2019 Great Lakes Hop and Barley Conference.

Based on the soil test results, fertilizer can also be purchased prior to the end of the year. Fertilizer is often cheaper in the fall compared to spring when demand is high. Purchasing fertilizer prior to the end of the year could also potentially have favorable tax implications.

Lastly, soil testing laboratories are busier in the spring compared to fall, as a majority of farmers, gardeners and homeowners wait until spring to soil test. A longer wait for soil testing results may force delays in fertilizer timing. There are several good quality labs available to Michigan farmers, including the MSU Soil and Plant Nutrient Laboratory. Details on submission, interpretation, fee schedule and more can be found by visiting the MSU Soil and Plant Nutrient Laboratory website.

Soil testing labs

Plant-tissue labs

Comprehensive soil health testing labs

Cover crops

Fall may also be a good time to seed in cover crops. Cover crops can offer multiple benefits depending on farm needs and species selection. For example, a fall-planted cover crop may scavenge and store excess nitrogen that can then be disked in the spring to coincide with hop nutrient uptake. Other cover crops can break up a clay hardpan, provide beneficial insect habitat, reduce erosion or help build soil organic matter. “Managing Cover Crops Profitably, Third Edition” is an outstanding free resource that offers detailed management information for many common cover crops. You may also be interested in the Midwest Cover Crop Council’s Cover Crop Decision Tool that helps you select cover crops based on specific needs.

Planning for next year

It is well worth your time to set aside a moment to reflect on the season. Take note of trouble areas in the hopyard and consider planning how to address pest or nutrient issues the following season. Also, review your spray records to ensure they are complete and begin investigating a food safety plan for next season. For more information on record keeping, visit the Resources page of the MSU Pesticide Safety program.

Virus testing

MSU Plant & Pest Diagnostics is now providing testing for hop viruses and viroids! Please refer to the recent MSU Extension article, “MSU Plant & Pest Diagnostics provides testing for hop viruses and viroids,” for information on costs and protocol for submitting samples.

Stay connected

For more information on hop production, visit www.hops.msu.edu.

This work is supported by the Crop Protection and Pest Management Program [grant no 2021-70006-35450] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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