Crop Profile for Hops in Oregon

• Oregon ranks second in U.S. hop production. Washington State leads, and Idaho is in third place, making the Pacific Northwest the nations' leading hop-growing area with 94% of all hop production.
• In 1996, Oregon held 16% of the U.S. market share and 4% of worldwide hop production.
• Growers harvested 6,162 acres of hops in 1998 with a yield of 10,339,000 pounds valued at $16,853,000. These figures are down from 1997.
• Total hop production costs are $3,527.01 per acre.
• Most hops are used as flavoring agents in beer.
• Pacific Northwest hop growers export 60% of their crops annually.

Production Regions

The Willamette Valley’s Marion County growers farmed 7,310 acres of the state’s 8,353 acres in 1997. Polk and Clackamas County growers farm small acreages, and in 1998, these acres were reduced (6, 8).

Hops need a rich volcanic soil, moderate temperatures, plenty of sunlight during the growing season, and abundant irrigation. Planted as rootstock, hops grow on trellises. Some plants survive for 50 years, but growers replant hop hills every 9 - 10 years to achieve optimum yields.

Farmers remove old bines (erroneously called vines) and debris in the spring and cultivate until late June or early July. When the fibrous root system has developed, it needs to be protected until the harvest is completed. Growers begin to irrigate in May or early June after they have trained the hop plants up twine supports (4).

The female plant hop cones are the hops of commerce. From August to mid-September, farmers cut the whole bine and haul it for mechanical picking (5).

For more cultural practices, pictures, and other information, see the Crop Profile for Washington Hops at http://ipmwww.ncsu.edu/opmppiap/subcrp.htm (9).

Aphid is a primary pest of hops. Hop aphids excrete lots of honeydew, and the sooty mold that grows on the honeydew can render hop cones unmarketable (10).

Other pests include armyworms, cutworms, loopers, caterpillars, earwigs, leafrollers, leaftiers, beetles, weevils, and spider mites (11).

Chemical controls:
Hop growers spray insecticides on 100% of their hop acreage to control hop aphids. Growers have used imidacloprid (Admire) as the chemical of choice in recent years, and it has largely replaced diazinon (10).

The Pacific Northwest Insect Control Handbook lists the pesticides that are used by Oregon hop growers: diazinon, malathion (Cythion), methyl parathion (Penncap), B.t., naled (Dibrom), bifenthrin (Brigade), insecticidal soap, imidacloprid (Admire), phorate (Thimet), dicofol (Kelthane), and propargite (Comite) (11).

Oregon farmers reported use of the following insecticides on 7,900 acres in 1992 (12):

Farmers expect pymetrozine (Chess) to be registered for aphid control in hops by the year 2000 growing season (9).

For more details on insect control in Oregon hops, see the 1999 PNW Insect Control Handbook, pages 103–105. (Go to http://eesc.orst.edu/agcomwebfile/edmat/ for ordering information.)

Alternatives:
Gianessi notes that "Diazinon is used currently as an early season spray for aphid control and is also important for resistance management for imidacloprid." (10)

Hops suffer from mildew, canker, root rot, wilt, and various virus diseases (16).

Hop powdery mildew (HPM) was detected in the Northern Willamette Valley in late July 1998. This disease has the potential to be extremely damaging. HPM is now present in all U.S. production regions. It caused the failure of the eastern hop industry in the early 1900’s and is a major problem in England and Europe (17).

Downy mildew of hops is another important disease, especially in Oregon. Severe infection in some cultivars may produce a rot of the perennial crowns and losses are also due to cone infections (18).

Chemical controls:
For powdery mildew control, potassium bicarbonate (Armicarb) and sulfur are used in Oregon. Fosetyl-aluminum (Aliette WDG), coppers, and metalaxyl (Ridomil) are used in Oregon for downy mildew (16, 18).

Growers should consider applying registered fungicides to all varieties per the label for HPM control (17).

Fungicides used to control other plant diseases are metalaxyl (Ridomil), copper, and fosetyl-al (Aliette) (12).

Oregon farmers reported use of the following fungicides in 1992 on 7,900 acres (12):

For more details on disease control in Oregon hops, see An Online Guide to Plant Disease Control, http://pnwhandbooks.orst.edu/guide1998/index.htm (19).

Cultural controls:
A quarantine against powdery mildew prohibits entry of all outside hop plants and plant parts into Oregon. Growers can purchase rhizome cuttings (rootstock) only within the state for planting on Oregon farms (6).

One source reports that the two most popular varieties, ‘Willamette’ and ‘Nugget,’ do not react to necrotic ring-spot virus and are somewhat resistant to downy mildew. However, downy mildew in ‘Nugget’ plantings is not uncommon. ‘Willamette’ is susceptible to verticillium wilt (6, 18).

Some of the most HPM susceptible varieties are Galena, Chelan, Tillicum, Symphony, and Northern Brewer. Researchers don’t know enough about the pathogen genetics to state with any confidence that cultivars other than Nugget are resistant to HPM. (17, 18)

Besides purchasing Oregon rootstock of a resistant variety, hop growers control hop disease by these practices (16):

• removing diseased hills
• destroying debris
• preventing situations that lead to standing water
• controlling bottom growth
• pruning crowns to eliminate infected buds and flag shoots

To address the recent HPM outbreaks, growers should consider a range of actions that include (17):

• removing all highly susceptible varieties and re-planting only resistant varieties
• rouging out all off-type or unidentified hops as their susceptibility is unknown
• destroying all feral or escaped hops in the production area
• plowing out aerial buds in the early spring to reduce overwintering inoculum
• composing or kiln-drying all hop leaf and vine material before returning it to the yard for plowing
• removing or plowing all diseased material that remains in the yard after harvest

Biological controls:
Ampelomyces quisqualis (AQ10) is a fungal hyperparasite on powdery mildew fungus. It is not compatible with some other hop treatments such as sulfur (16, 20)

Hop cyst nematodes can move on hop roots and in floodwater (16).

For more details on nematode control in Oregon hops, see An Online Guide to Plant Disease Control, http://pnwhandbooks.orst.edu/guide1998/index.htm (19).

Cultural controls:
Specialists have been unable to develop cultural controls for nematodes (16).

Other:
In 1992, Oregon farmers used small amounts of gibberellic acid (Pro-Gibb) to increase yields (12).

Quackgrass and field bindweed are the most troublesome weeds in hops (13).

Chemical controls:
Herbicides used to control hop weeds, suckers, and to burn down unwanted vegetation are paraquat (Gramoxone), norflurazon (Solicam), trifluralin (Treflan), and endothall (Des-I-Cate) (14).

Oregon farmers reported use of the following herbicides in 1992 on 7,900 acres applied in bands or spot treatments (12):

For more details on weed control in Oregon hops, see the 1999 PNW Weed Control Handbook, pages 135–136. (Go to http://eesc.orst.edu/agcomwebfile/edmat/ for ordering information.)

Alternatives:
Scientists have studied alternatives to soil residual herbicides for their effects on weed control, yield, and hop quality (15).

Cultural controls:
Regular cultivation provides weed control and improves soil texture (4).

Ann George
Washington Hop Commission
504 N. Naches Ave, Suite 11
Yakima, WA 98901-2457
whchgw@televar.com

Gale Gingrich
Marion County Extension
3180 Center St NE. Room 1361
Salem, OR 97301
Gale.Gingrich@orst.edu

Sam Likens
Hop Research Council
3815 Glenwood Loop SE
Salem, OR 97301
http://www.usahops.org/Research.html

Cindy Ocamb
Botany and Plant Pathology
Oregon State University
Corvallis, OR 97331
ocambc@bcc.orst.edu

Michelle Palacios
Oregon Hops Commission
152 Chemawa Rd. N
Salem, OR 97303-5356
cchop@oda.state.or.us

1. Crop Profile for Commodity in State. http://pestdata.ncsu.edu/CropProfiles/ instructions.html (accessed Feb 1999).

2. 1998 Oregon County and State Agricultural Estimates, Special Report 790. Oregon State University Extension Service, revised April 1999.

3. Enterprise Budget, Hop Production, Willamette Valley Region, Oregon State University, EM 8434, May 1990.

4. Hop Growers of America. http://www.usahops.org/HGA.html (accessed Feb 1999).

5. Markle, G.M.; Baron, J.J.; Schneider, B.A. Food and Feed Crops of the United States, Second Edition; Meister Publishing Co.:Willoughby, OH, 1998.

6. Oregon Hop Commission. http://www.oda.state.or.us/hop/ohc.html (accessed Nov 1999).

7. Oregon's rank in the nation's agriculture:1996. http://www.oda.state.or.us/oass/ bul0697.htm (accessed Oct 1998).

8. Agricultural Commodity Sales, Marion Country, 1997, Economic Information Office, Oregon State University, April 16, 1998.

9. Crop Profile for Hops in Washington. http://pestdata.ncsu.edu/cropprofiles/Detail. CFM?FactSheets__RecordID=85 (accessed July 1999).

10. Gianessi, L.P. The Uses and Benefits of Organophosphate and Carbamate Insecticides in U.S. Crop Production. http://ext.agn.uiuc.edu/piap/gianessi/oppap02t.htm (accessed June 1999), National Center for Food and Agricultural Policy, Washington, DC

11. Pacific Northwest Insect Control Handbook; Extension Services of Oregon State University, Washington State University, and the University of Idaho: Corvallis, OR, 1998.

12. Rinehold, J.; Jenkins, J.J. Oregon Pesticide Use Estimates for Seed and Specialty Crops, 1992; EM 8568; Oregon State University Extension Service: Corvallis, OR, September 1994.

13. Bridges, D.C., Ed. Crop Losses Due to Weeds in the United States – 1992; Weed Science Society of America: Champaign, 1992.

14. Pacific Northwest Weed Control Handbook; Extension Services of Oregon State University, Washington State University, and the University of Idaho: Corvallis, OR, 1998.

15. Blackman, J.D.; Rees, L.; Glendinning, P.J. The effects of alternatives to soil residual herbicides on weed control, yield and quality of hops, HortScience 1996, 71(4), 629-638.

16. Pacific Northwest Plant Disease Control Handbook; Extension Services of Oregon State University, Washington State University, and the University of Idaho: Corvallis, OR, 1998.

17. Hop Powdery Mildew; O.D.A. Pest & Disease Alert; Oregon Department of Agriculture, Plant Division: Salem, OR, February 1999.

18. Ocamb, C. Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR. Personal communication, August 5, 1999.

19. An Online Guide to Plant Disease Control. http://pnwhandbooks.orst.edu/ guide1998/index.htm (accessed July 1999), Oregon State University, Corvallis, OR.

20. Meister, R.T. (Editor), 1999, Farm Chemicals Handbook '99, Meister Publishing Company, Willoughby, OH.

Acknowledgements
This document was prepared by P. Thomson, W. Parrott, and J. Jenkins, Agricultural Chemistry Extension, Department of Environmental and Molecular Toxicology, Oregon State University. The information was reviewed by C. Ocamb, Botany and Plant Pathology, Oregon State University.