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

Project Overview

Project Type: Farmer
Funds awarded in 2012: $12,654.00
Projected End Date: 12/31/2013
Region: Northeast
State: Maine
Project Leader:
Krista Delahunty
Aroostook Hops
Dr. Jason Johnston
Aroostook Hops

Annual Reports


  • Agronomic: hops


  • Crop Production: cover crops, organic fertilizers
  • Pest Management: chemical control, integrated pest management
  • Production Systems: organic agriculture
  • Soil Management: green manures, soil analysis, soil chemistry, soil microbiology

    Proposal summary:

    Commercial hops production has been largely absent in the northeastern U.S. since the 1920’s, even though there is significant craft and microbrewery beer production here. Throughout the northeastern U.S., a variety of growers have raised hops for use by brewers. The main problem is how do small-acreage hops farmers produce a profitable hops crop? Hops cultivation practices recommended for the Northwest cannot be simply applied to the Northeast due to these differences in climate and scale. A primary challenge for the small-scale and organic northeast hops grower is weed control. With the Northeast hops industry in an early and robust state of expansion, best practices for establishment of a hopyard with a sound weed management strategy is paramount to maximizing production and profitability, especially when farmers are responding to market demands for non-pesticide produced hops. Perennial hops have unique weed management challenges versus annual crops. While tilling may be used to control weeds, too much tilling may reduce proper rhizome and root growth. Aroostook Hops, LLC is an established hops farm in northern Maine, which produces economically and environmentally sustainable hops for Northeast brewers. In 2012, we are expanding our farm by 3 acres. We will examine best non-herbicide approaches to weed management as well as the best practices for the initial establishment of a hopyard to minimize weed populations. As a member of the Northeast Hops Alliance, and through our website, aroostookhops.com, we will provide a detailed report, which describes our weed management study. We will work closely with NEHA to incorporate our findings into a developing Northeast comprehensive hops management plan.

    Project objectives from proposal:

    We have spent the last three years researching and experimenting with irrigation, methods to improve soil nutrients, reduce labor associated with weed control, and improve other aspects of small-scale hops cultivation. Since we aim for commercial viability we plan to manipulate factors that we expect to significantly increase yield or reduce labor.

    We will investigate the best strategy to establish and maintain a hopyard with minimal weed populations. Our experimental methods will address the following two questions:
    1) what is the best non-herbicide cultural practice to control weeds (none, straw, tilling), and
    2) is a weed-suppressing cover crop effective in reducing weed populations and is it worth delaying hops planting by a year.

    In spring, 2012 we will establish 3 additional acres of hops. This land was previously pasture (2009-2010) or fallow (2011) before we purchased the land in 2011. In October 2011 the land was plowed, disced, and soil tested. It abuts lawn, old field, fallow field, and cultivated land.

    To investigate question 1, we will establish hops plantings in 2012 and use three approaches to manage weeds between plants (‘intrarow’): no control, 5 cm straw mulch, or bi-weekly tilling. We will conduct these practices during 2012 and 2013 to be able to measure weed impacts on both one-year old and two-year old hops plants.

    To investigate question 2 we will establish half our new hopyard in a weed-suppressing cover crop (rapeseed, Brassica napus) for year one. We will also maintain an area of fallow land to permit same-year comparisons.

    In 2013, we will establish hops plants in previously fallow versus previously covered plots. We will use three varieties of hops (Cascade, Centennial, and Mount Hood) which have different growth characteristics and represent commonly grown hops with the Northeast.

    We will measure our results by comparing hops linear growth, weed biomass, weed composition, and soil biology across treatments (n>10 per treatment except for soil biology) and varieties. Hops linear growth will be measured as the total plant height from soil to apical tip. Weed biomass and composition will be measured using 0.5 m2 quadrats, in which i) all stems are cut and massed for total weed biomass, and ii) # stems for each weed species are counted. Soil biology will be tested to assess microbial activity differences between fallow, fallow/tilled, fallow/straw, and previously covered plots; however, since only one soil test per treatment will be conducted results will be qualitative only.

    To assess question one, we can compare fallow versus straw versus tilling in one year and two year hops. To assess question two, we will compare previously fallow versus previously cover cropped plots’ one–year old hops plant linear growth and weed biomass and composition. We will compare hops planted after cover (2013), with hops planted after fallow in 2012 as well as planting hops on fallow plots during 2013 to control for year effects. ANOVA with Tukey’s test will be used to test significance of potential differences in linear growth and weed biomass. Differences in weed species counts will be transformed to normal before conducting parametric tests. We will also measure time spent conducting all activities and materials costs, in order to produce a standardized dollar value for cost per acre by treatment.

    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 or SARE.