Proposed Dates of Use: April 1, 2023 – May 31, 2023

Street Address/Site Name: City of Davis, Wastewater Treatment Plant, 45400 Country Road 28H

Detailed Location of Application Site: Road tops, edges, rock areas where run off is unlikely to occur. Rock area around clarifiers and solids building.

Posting and Notification: A notice of 72 hours will be given before the application. No applications will be in the vicinity of playgrounds, schools or picnic areas. Additionally, this area can be locked down restricting the use of pedestrian traffic.

Pesticide Products:

Product (W/ active ingredients): Round up Custom – Glyphosate 53.8%
EPA Reg #: 524-343
Pesticide Type: Herbicides
City Use Type: Tier 1 limited use, most restrictive.

Target Pests: Pepper weed, short-pod mustard, black mustard, Italian thistle, yellow star thistle, milk thistle, fluellin, other annual weeds

Justification for Use: This herbicide use is justified due to the need for safe access to these critical infrastructure facilities year –round. PW staff need to be able to safely access stations, roads and facilities throughout the year to perform maintenance and react to changing conditions during the rainy season. Also, the Treatment Plant has a regulatory requirement to keep levees free of vegetation for State inspectors. The chemical identified here will provide effective control of the broad range of vegetation that is found in and around the listed sites. By performing well-timed herbicide applications, PW staff will be able to reduce the amount of vegetation without compromising the rest of their mission.

Pepper weed is of particular concern because there is no reliable way to control it without herbicide. Mechanical cultivation or hand hoeing are not options because the plant can reproduce from vegetative material and these methods will actually increase the infestation. The plant can cause damage to stations and road tops because it’s large, tuberous roots can undermine pipes, foundations and other facilities. There is no reliable way to kill these weeds using non-chemical methods at the scale they exist on the sites.

Explanation of IPM Methods Used: Staff will only use herbicides in the areas identified above. All other acreage included in storm water management areas is maintained without pesticides. Areas that can be mowed or trimmed will receive those treatments, as needed to keep access clear and fire risk low. Crews will do hand trimming, and pruning in areas that mowing is not accessible by tractors.

Strategies to Prevent Future Applications: Effective, well-timed control will decrease pesticide usage over time because less seed and reproductive material will be present in the soil. However, the need for access to secure public safety may affect this trend, depending on conditions such as rainfall amounts, timing and ground temperature. We propose to reduce our use in the following ways:

• Keep Oxidation ponds maintained per State recommendations.
• Practice responsible vehicle access during wet months to prevent road damage and the need for repair work that is a vector for invasive species.
• Clean and maintain all equipment before and after use to prevent the transfer of seeds and plant materials between sites and/or into sensitive areas.
• Continue to use hand and power tools to keep control of the weeds as much as possible.

More information on the IPM Program, including the current Policies and Procedures guidance, can be found on the City's webpage: Integrated Pest Management