The effect of crowning and weed management practices on hop yield and downy mildew

View the project final report

Commodities

• Agronomic: hops

Practices

• Crop Production: organic weed management

One of the biggest challenges continuing to face east coast growers, and especially on organic farms,
is effective control of downy mildew (DM), which thrives in moist environments typical here. In
order to assess whether effective weed control significantly in combination with DM control
practices reduces DM presence and economic loss, we will compare the relative rate of DM infection
at four key time points in the growing season, from spring through post-harvest. This split-plot
design will consist of whole plots of two hop varieties (Mt. Hood: susceptible to DM infection, and
Cascade: moderately resistant) that are either crowned in spring or not, with three experimental
treatments and control as each set of split plots: 1) sheep-weeded hopyard with no fungicide, 2)
organic herbicide plus fungicide, and 3) fungicide only, and 4) a control plot with no sheep or
organic herbicide. DM will be quantified using qPCR to measure relative DM loads in early spring,
summer, pre-harvest and post-harvest. In addition to quantifying relative DM presence in each
group, we will also measure hop yield at harvest time, and quantify material and labor costs
associated with each management practice to compute per acre costs, and assess the trade-offs of
each practice. Outreach will consist of hosting a field day, preparing a manuscript, and sharing
results with Northeast farmers and researchers, on the web and via social media.

In order to assess whether effective weed control and DM management practices significantly
reduce DM presence and economic loss, we will compare the relative rate of DM infection at four
key points in growing season, from spring through harvest in two hop varieties (Mt. Hood:
susceptible to DM infection, and Cascade: moderately resistant), crowned or not, using three
experimental treatments and control as each set of split plots: 1) sheep-weeded hopyard with no
fungicide, 2) organic herbicide plus fungicide, and 3) fungicide only, and 4) a control plot with no
sheep or organic herbicide. In addition to quantifying relative DM presence in each group, we will
measure hop yield at harvest time, and quantify material and labor costs associated with each
management practice to compute per acre costs, and assess the trade-offs of each practice. If
reduction of weeds and lower bine leaves effectively controls DM, then farmers could determine if
organic herbicide (expensive), or sheep (not allowed under organic certification) are worth
employing over less expensive cultivational practices alone, or in comparison to the environmental
concerns of copper-based fungicide. Thus, the solution may inform both organic certified and
non-certified hops farmers to maximize yield/profit with environmental concerns.