Leafhopper Insecticide and Particle Film Summaries

4 leaves are in a shallow dish of dirt, in a white insect net cage

2020 and 2021 Leafhopper Insecticide Trials

By Dr. Louis Nottingham and Dr. Katlyn Catron

Methods:

Colladonus reductus leafhoppers were collected from organic or unsprayed orchards’ groundcover (Fig. 1) via sweep nets, then returned to the lab. Leafhoppers were exposed to insecticides by direct sprays or previously treated leaves from cherry trees. After exposure, leafhoppers were kept in ventilated arenas with treated cherry leaves (Fig. 2) for 24-48 hours, then rated as alive or dead. Between 25-50 leafhoppers were examined per treatment in each experiment.

Combined 2020 & 2021 Results:

Columns show average percentage mortality (dead ÷ total x 100) from each insecticide and exposure type. Values above dotted line are averages from at least two trials; below are from a single trial.

2021 Particle Film and Oil Repellency Trial

By Dr. Louis Nottingham and Dr. Katlyn Catron

Methods:

Leafhoppers were collected from orchard groundcover and returned to the lab. Forty leafhoppers were added to cages with leaves treated with either H20, IAP oil 1%, Surround WP (kaolin) 50 lb/acre, or Celite (diatomaceous earth) 50 lb/acre (Fig. 3). Four experiments were conducted. In the first two, Surround and Celite were mixed with 1% oil, in the second two, no oil was mixed with these two products. Two visual evaluations were conducted for each experiment, (5 hours and 24 hours after treatment) to determine how many leafhoppers occupied each leaf.

Results:

Leaves treated with Surround or Celite had the fewest leafhoppers, followed by 1% Oil (Fig. 4). Some leafhoppers were found on Surround, and Celite treated leaves, generally in areas with less or no particle film residues. Although particle films demonstrated significant repellency in this test, more testing is needed to understand if particle films or oil can reduce the spread of x-disease phytoplasma.

Fig. 4. Presence of leafhoppers on treated leaves. Treatments not sharing a letter are significantly different.

Funding: Thanks to the WA Tree Fruit Research Commission and OR Cherry Groups for research funding.

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