Vegetable Crops

Healthy Soils Project Updates

-Multisite demonstration of conservation management practices for soil health and greenhouse gas emissions reduction

UCCE Agronomy Advisor, Sarah Light, and myself have finished our 3-year statewide Healthy Soils Demonstration Project supported by CDFA.  This project included a cover crop demonstration and research site on a farm in Sutter County in addition to two other sites statewide (San Joaquin and Merced County). We evaluated the impact of cover crops to soil health and annual production in the region. Our plots consisted of a control (no cover crop), a low seed rate of vetch, and a high seed rate of vetch. Unfortunately, we cancelled our March 2020 field day due to COVID-19 precautions but we developed a couple of informational handouts with cover crop information and they can be found here.  

-Evaluation of compost application to processing tomato fields in the Sacramento Valley

In Fall 2020, I started another 3-year Healthy Soils Demonstration Project to look at the effects of compost application to processing tomato fields. I have two sites for this project, one is located in Colusa County and the other in Sutter County. Our treatments include compost application at 3 tons/acre and 6 tons/acre, and a fallow control. I am working with Westside Spreading, LLC on this project and it is funded by the CDFA. We will be having annual field days, so please be on the lookout for those announcements in the coming year. 

Processing Tomato Project Updates

In 2021, with help from Cassandra Swett and Bob Gilbertson at UC Davis, we diagnosed Beet curly top virus (BCTV), Tomato spotted wilt virus (TSWV), resistance-breaking-TSWV, Fusarium wilt, Fusarium falciforme, Fusarium crown and root rot, bacterial canker, charcoal rot, root-knot nematode, and southern blight from field visits and samples. In the Resources section below, you can find a Fungal Disease Diagnosis handout from Dr. Cassandra Swett with more information on diagnosing various wilts and crown rots.

The northern counties saw an outbreak of BCTV in 2021 in both tomatoes and cucurbits. In addition to BCTV, the resistance breaking-TSWV has been found in the Sacramento Valley as well. More information on both of these viruses can be found in the special virus addition of my newsletter, July 2021. 

-Weed control and cost-benefit analysis of automated cultivators to control within-row weeds in processing tomatoes

The main objective was to evaluate crop safety, weed control, time, and costs associated with using mechanical cultivators as part of a conventional weed management program in processing tomatoes. While both robotic cultivators and finger weeders have been used and evaluated in many vegetable crops, there has been little research evaluating these tools in processing tomatoes and how well they may complement or replace a traditional herbicide program or reduce hand weeding costs. We conducted replicated trials at two sites (Colusa and Merced counties) comparing the Robovator (automated weeder), finger weeder (mechanical), and rimsulfuron application to control plots where there was no in-row cultivation and no post-transplant herbicide application. This project was conducted in 2020 and 2021.

Key Takeaways:

• High interest for within-row mechanical cultivators
• Robovator provided excellent control in Colusa in 2020, but caused crop injury in Merced, and in Colusa in 2021
  • High winds/non-upright plants affect precision of Robovator and lead to higher % crop injury
• Finger weeder provided excellent weed control in both fields in 2020, except for one plot in Colusa field with heavy bindweed
• Rimsulfuron and finger weeder treatments reduced costs and time for hand weeding in Merced, and rimsulfuron and both cultivators reduced costs in Colusa compared to the control

Many thanks to our grower cooperators in Colusa and Merced counties; Steve Fennimore, Weed Management Specialist with UC ANR in Salinas for use of Robovator; and the California Tomato Research Institute for their funding and support.

More information on both projects can be found in the March 2021 and January 2022 Vegetable Crops Newsletters and in the October 2021 issue of CAPCA Adviser magazine.

-Pest Management Strategic Plan for Processing Tomatoes

A Pest Management Strategic Plan (PMSP) is a planning document that details the critical needs for pest-management issues and management practices in a particular crop. Currently, there is no PMSP for processing tomatoes. PMSPs are developed through stakeholder input and document critical needs and priorities to help justify research funding and regulatory needs.

In 2019, processing tomato growers from across California, along with commodity boards and UCCE Advisors and Specialists, gathered to discuss the priority research, regulatory, and education needs for California processing tomato. The final document was published in 2021 and can be found here. This project was funded by the Western Integrated Pest Management Center.

Melon Project Update

-Management of spotted and striped cucumber beetle in melon production

We evaluated insecticide efficacy against cucumber beetles at a research farm on the UC-Davis campus for a second year. This was scheduled for 2020, but due to COVID restrictions it was delayed to 2021.We included conventional and organic insecticides and also evaluated the addition of a gustatory stimulant. We will be repeating this in 2022 with a more refined insecticide list to clarify the relationship between insecticides and the feeding stimulant.

Because we currently have a poor understanding of where western striped cucumber beetle overwinters before moving into melon fields, we monitored likely overwintering locations (weedy vegetation around fields) in organic fields in 2020. We found beetles on broadleaf weeds, including milk thistle, burclover, mustards and little mallow. In 2021, we conducted feeding choice assays (in the lab) using these weeds and found that western striped cucumber beetles have a preference for milk thistle, but will also feed on mustards and not on mallow.

We also continued testing the aggregation pheromone for the eastern cucumber beetle species for its attractiveness to the western species of cucumber beetles. An aggregation pheromone has been identified and developed for the closely related striped cucumber beetle found in the eastern U.S. (Don Weber, USDA-ARS), and it has recently been determined that this is the same aggregation pheromone used by the western striped cucumber beetle. The addition of the pheromone enhanced capture of both western striped and spotted cucumber beetles in 2020. In 2021, we added a floral lure to the pheromone baited traps, and captures were very high, especially late in the season. The pheromone traps were unable to compete with fresh-market melons in the field during the season, but were effective at capturing beetles in the spring and fall. This research was funded by the California Melon Research Board.

Our cucumber beetle research was featured in the October 2020 issue of CAPCA Adviser magazine.

A profile on cucumber beetles was also published in the Journal of Integrated Pest Management in January 2021 and a summary can be found on Entomology Today.