The Effect of Edge-spraying a Broad-spectrum Organically-approved Insecticide to Control Hop Arthropod Pests while Retaining Beneficial Arthropods

View the project final report

Commodities

• Agronomic: hops

Practices

• Pest Management: chemical control, integrated pest management
• Production Systems: organic agriculture

The most common and impactful arthropod pests on our hops farm are potato leafhopper (PLH), damson hop aphid (DHA), and two-spotted spider mite (TSSM). Control of these pests using broad-spectrum insecticide has the negative impact of also eradicating beneficial arthropod predators.  It has been established that PLH and DHA are more likely to establish at field edges, so controlling them by spraying only in this zone could depress pest population growth while leaving a large area of refugia for beneficial insects and predators.  This could potentially increase yield, reduce pesticide use, and retain beneficial predators. We propose to test whether spraying pyganic at the edge of a hopyard only will effectively control arthropod pests in the whole yard by comparing use of pyganic versus a water control at the hopyard edge versus interior.  We will measure the abundance of both pest and beneficial arthropods (using sticky traps and leaf counts), hop yield, visual evidence of PLH leaf burn, and cost-benefit analysis.  Outreach will consist of an on-farm field day, a report summary on our website page that highlights our research, social media posts with pictures and videos, creation of PowerPoint slides to include in talks, and potentially, submission of a paper to a journal.

This project seeks to determine whether spraying PyGanic on hop field edges will reduce arthropod pest populations, while also minimizing negative impacts on beneficial predator species.   

Objective 1) To determine if some hops pests (PLH and DHA) establish at field edges first.

Objective 2) To determine if spraying a broad-spectrum lethal pesticide at hops field edges, in combination with less lethal insecticides throughout the whole field, can reduce populations of arthropods pests and prevent spread into the hop field interior.

Objective 3) To determine if this spatially adjusted insecticide application can minimize impact on beneficial predatory arthropods, and not lead to a spike in TSSM populations.    

Objective 4) To determine if hop yield is higher in subplots sprayed with PyGanic vs. control and edge vs. interior.      

To accomplish these objectives, we will measure the number of pest and beneficial arthropods in each experimental condition.  We hypothesize: 1) that spraying the field edge will reduce hops arthropod pests at the edge which will reduce their spread and establishment within the entire hopyard, and 2) that beneficial arthropods will be retained in the interior hopyard due to applying PyGanic at the edges, limiting mortality to beneficials here only.