Some of my weed science extension colleagues in the midwest have a podcast called War Against Weeds supported with funding from the North Central IPM Center. I was interviewed on the podcast a few years ago about herbicide resistant weeds in orchards. Earlier this week, they invited me back as the first interviewee of their 11th season where we talked about branched broomrape in California processing tomato.
The use of walnut leaf biomass as a natural mulch and an eco-friendly practice can help prevent weed seed germination by excluding light and/or acting as a physical barrier that prevents weed emergence. Beyond that, several studies have shown potential allelopathic effects of juglone and leaf extracts of walnut on seed germination and seedling root and shoot growth (Kocacë and Terzi, 2001; Zhang et al., 2008; Chauhan et al., 2022; Đorđević et al., 2022).
Fig. 1. Walnut leaf mulch small plots trial as a low-input strategy for weed management.
To provide better recommendations on how to best use rimsulfuron and other residual herbicides to target johnsongrass I established a set of trials in Shasta and Tehama county prune and walnut orchards in winter and spring of 2025. I had two primary goals: first, to test if early spring rimsulfuron applications were effective for control of johnsongrass and second, to determine whether treatments were primarily affecting seedlings or established populations.
Weed Science School is less than two weeks away! Join the UC Davis Weed Research and Information Center for this 2.5 day course. Learn through lectures and laboratory demonstrations at the Bowley Plant Science Teaching Facility at 1200 Extension Center Drive in Davis, CA on September 16-18, 2025.
In California, the Department of Pesticide Regulation (DPR) has a license and certification system which allows for professionals to apply pesticides as a part of their job duties. While everyone using pesticides must follow all directions on the pesticide label, as well as any additional state or local regulations, professional applicators need to follow additional regulations. Most employees who spray pesticides hold a qualified applicator license (QAL) or qualified applicator certificate (QAC).
Sharing a link to an article posted by the UC Davis Department of Plant Sciences recapping the 28 year career of Cooperative Extension Weed Scientist Dr. Steve Fennimore.
My name is Mandeep Singh, and I’m honored to serve as the Agronomy Advisor for Sacramento, Solano, and Yolo counties, based at the UCCE Capitol Corridor office in Woodland. From an early age, I was involved in managing row crops like alfalfa, wheat, cotton, rice, sorghum, and oats, as well as caring for livestock on my family's farm. I did my bachelor’s and master’s degrees in agronomy from Punjab Agricultural University.
Branched broomrape (Phelipanche ramosa) is an invasive parasitic plant that poses a significant threat to California’s processing tomato industry. Known for its ability to attach to and draw nutrients from host roots, this pest can cause yield losses and trigger strict quarantine measures in California commercial fields. Building on Israel’s PICKIT approach for Egyptian broomrape (P. aegyptiaca), California researchers are working to adapt and refine chemigation-based herbicide strategies that target this challenging weed without harming tomato crops.
Branched broomrape (Phelipanche ramosa) continues to challenge California’s processing tomato industry, particularly in the Sacramento Valley. As a parasitic plant that attaches to tomato roots, its presence threatens both yield and export market access. In a recently published study in Weed Technology, we evaluated the efficacy of chemigated rimsulfuron—a recently registered approach with potential to offer targeted, soil-based suppression of this invasive pest.
New WeedCUT Feature: BMPs for Herbicide Application Techniques
Confused about what a “drizzle” application is and when to use it? Deciding on the best way to estimate your application rate when using a backpack sprayer? Wondering what your hole spacing should be when using “drill-and-fill”?
A recommendation bulletin has been released for florpyrauxifen-benzyl (Loyant® CA, Corteva Agriscience LLC, Indianapolis, IN, USA) to control cattail plants in California rice fields and permitted under FIFRA Section 2(ee). Cattail (Typha latifolia L.) also known as common cattail or broadleaf cattail is a perennial wetland weed that naturally occurs widely in nearly all North America and are often considered undesirable, weedy, or invasive. Common cattail is cosmopolitan weed that can grow up to 10-ft tall under favorable conditions.
