Evaluating Cover Cropping and Non-Herbicide Weed Management Strategies in Hops, a Perennial Crop

Summary

For the past two years, we have conducted an experiment to investigate the best approach to non-herbicide weed management in a newly established Northeast hopyard. In 2012, we established a new 3-acre hopyard with four varieties: Cascade, Centennial, Mount Hood, and Willamette. We have implemented three cultural approaches to weed management: straw mulch, tilling, and nothing (control). We are also investigating whether planting a weed-suppressing cover crop (rapeseed) is effective enough in suppressing weed emergence to justify delaying planting rhizomes for the first year.

Our technical advisor is Marcus Flewelling, crop specialist with Crop Production Services in Mapleton, Maine. Marcus continues to support us with product recommendations, IPM management, and visits on-site to aid us where needed. We also regularly consult with Dr. Heather Darby at The University of Vermont’s Hops Project for advice and guidance.

Aroostook Hops is a 4-acre, 5-year old established hop farm in northern Maine. We sell whole cone hops and rhizomes, with varieties including Nugget, Willamette, Mount Hood, Centennial, and Cascade.

Objectives/Performance Targets

Accomplishments/Milestones

In 2012, we established our new hopyard and planted over half with rhizomes of four varieties, which we maintained in one of our three cultivation approaches (straw, tilling, control: nothing). Another part of our new hopyard was planted in 2012 with a weed-suppressing cover crop (rapeseed, Brassica napus). A third portion was left fallow for comparison. In the late fall of 2012, the rapeseed was mowed and tilled into the soil. In spring of 2013, we planted more rhizomes of the same four varieties in the previously cover-cropped area and again maintained them in three cultivation approaches (straw, tilling, control: nothing).

We measured the results of our experiment using multiple approaches. For each variety (n=4) /age (n=2) /cultivation treatment (n=3) /cover cropping (n=2) combination, (n=48 total), we measured plant linear growth (soil to apical tip) and weed biomass and composition in 0.5m² quadrats (n=10 per group). Composition was measured by recording the percent a weed appeared in a full quadrat, and biomass was measured by cutting all weed material in a quadrat and recording its mass (g). Soil tests (including microbial activity) were taken from each cultivation method/cover cropping combination (n=6).

On Labor Day weekend of 2013, we hosted a hops field weekend, which drew about 80 people interested in learning about hops (some planning to begin hop farming locally) and resulted in two local newspaper stories featuring our farm.

We have finished with the two years of fieldwork for our experiment, and in the coming winter months plan to enter, analyze, and summarize the data collected. We will write a report outlining our findings, and make it available as a pdf on our own website, as well as to any other groups who may be interested in sharing it.

Though we ultimately managed to recover enough data to salvage the experiment, one unexpected detrimental impact to attaining enough numbers per group for statistical analysis occurred with a low germination rate from Cascade rhizomes purchased through the Northeast Hop Alliance (NeHA) cooperative purchase, which averaged ~10% germination for Cascade rhizomes in 2012. This resulted in low numbers in our experimental groups for this variety, but we managed to pool data from more rows than planned for experimental purposes to get a total number of 10 or so per treatment group.

Impacts and Contributions/Outcomes

Collaborators: