Project Overview

Reports

Commodities

Target Pests

Practices

California rice systems face the highest number of herbicide-resistant weed species compared to any other crop or region in the U.S. While crop rotation is one of the most effective Integrated Pest Management (IPM) tools for managing herbicide resistance, it is rarely implemented in California rice production, largely due to the specific water requirements of rice, economic constraints and soil type limitations. A 2020 study involving 43 growers, representing about 15% of the state's rice production area, revealed significant interest in learning more about the benefits of crop rotations. It is estimated that roughly 12,000 acres (out of 500,000 total rice acres) are in rotation with annual crops in CA, primarily in Yolo, Sutter, and Colusa counties. Processing tomatoes is one of the most profitable crop rotation options; however, switching irrigation systems from drip-tape used in tomatoes to continuously flooded rice poses economic and logistical constraints that limit the adoption of this rotation option. To address this issue, some growers have been experimenting with drip-tape rice following tomatoes. Currently, research-based production guidelines for drip-tape rice do not exist and production challenges in this system have not been documented, so many rice growers lack the necessary information and tools to make informed decisions; this is an obstacle towards adoption of crop rotation that combines drip tape irrigation with rice farming. Another key barrier to adoption is the uncertainty about the economic impacts of switching to a different crop or cropping system. The primary objective of this project is to continue the work of the previously established Rice Workgroup  which will explore the feasibility and impact of crop rotation within existing drip-tape irrigation infrastructure as an IPM strategy for rice, with a specific focus on economics. The group will also lay the groundwork for long-term research addressing weed management and population dynamics. Key outcomes for this year include: 1) continuing the previous Rice Workgroup with stakeholders from across the rice and tomato industry: growers, Cooperative Extension faculty, Pest Control Advisors, and other industry members; 2) conducting an economic assessment of a tomato-rice crop rotation on drip-tape irrigation with the workgroup; 3) developing a crop-rotation decision support tool based on the economic assessment data; and 4) working with stakeholders to design a long-term research and extension plan and submit a larger funding proposal for alternative annual crop rotations in the Sacramento Valley. As extension specialists, we will use these decision-making tools and the accumulated data to enhance our ability to provide educational resources, information, and support through publications, workshops, and field days. Furthermore, the workgroup will play a crucial role in ensuring that extension programming, decision-making tools, and research planning are tailored to the real-world needs of the industry. Ultimately, this project—and those that follow—will help strengthen networks among growers, Cooperative Extension, and other key stakeholders, which will be instrumental in addressing future IPM challenges in rice production.

Under this work group development grant our direct objectives are to:

1. Identify key organizations, growers, and industry members who have a stake in rice pest management. Develop a collaborative work group of key stakeholders which include growers who currently practice rotations with rice, identified rice growers interested in trying rotations, growers who currently practice rotations with tomatoes on drip-tape irrigation, extension specialists and advisors both in and outside of the rice sector, as well as key industry personnel (Pest Control Advisers, Crop Consultants, etc.) (March­ - June 2025).
2. Using management information from growers and industry representatives within the work group, we will conduct a cost of production analysis for drip-tape irrigated tomato and rice crop rotations, which will be used as a framework to contribute more economic information to a decision making support tool for rice growers in the Sacramento Valley, “Rice Rotation Calculator” (June - September 2025).
3. Based on the cost analysis, augment the current decision support tool that assesses the economic feasibility of crop rotation, which will then be made available to growers through a web-based UC IPM Crop Rotation Calculator (October 2025-February 2026).
4. With grower and work group collaboration, design a multi-year research and extension plan and submit a larger proposal focused on IPM and alternative annual crop rotations in the Sacramento Valley (June-September 2025).