Planning for a new hopyard 2: Sourcing clean plant material is crucial for success

As the hop harvest winds down, current growers may be interested in expanding production and new growers may be developing business plans for establishing new hopyards next spring.

In addition to determining which varieties to plant, the focus of the previous article, a grower should also carefully consider where to source planting material. The first question that typically comes up is: rhizomes or propagated plants?

In the Pacific Northwest, rhizomes are generally harvested in early spring, February or March, and are then placed in cold storage until they are shipped out for planting. For growers in northern Michigan, this could be as late as May depending upon the severity of the winter. By the time we receive rhizomes, they could have been in storage for several months and the quality can differ quite dramatically depending upon the supplier. Unless you have a working relationship with the seller and know the rhizomes are of high quality and disease-free, Michigan State University Extension recommends purchasing plants that have been propagated from certified disease-free planting stock sourced from the National Clean Plant Network (for specific information please refer to: Purchasing hops for planting).

As downy mildew is now well-established in Michigan as explained in Battling downy mildew as hop harvest approaches and Downy mildew of hops already reported in Michigan for 2014, it pays to take extra precautions when planting new hopyards. Fortunately, nurseries that propagate hop plants in Michigan are inspected and certified by the Michigan Department of Agriculture and Rural Development. Growers, who would like to take extra precaution, could purchase a small number of plants from the nursery they are considering and send them to the MSU Diagnostic Services Laboratory to test for presence of downy mildew or other pests and pathogens.

While plants may test “clean”, an integrated pest management plan will need to be developed and will include preventative sprays that begin as soon as plants emerge, especially on highly susceptible varieties like Centennial. The take home message for growers is: When investing upwards of $15,000/acre in a hopyard, it pays to start with disease-free planting material and have a plan in place to deal with downy mildew prior to its appearance. For more information on hops, please visit Michigan State University Extension as well as MSU’s Hop webpage.

Other articles in this series:

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