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Vegetable Crops

Healthy Soils Project Update

 

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

2019 wrapped up the 2nd year of a 3-year statewide Healthy Soils Demonstration Project supported by the CDFA. This project includes 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 are evaluating the impact of cover crops to soil health and annual production in the region. We have taken baseline soil samples at our site each fall in Meridian, CA. In 2017 the field was planted to wheat, followed by a winter vetch cover crop, then processing tomatoes in 2019, and a vetch cover crop again in November 2019. Our plots consist of a control (no cover crop), a low seed rate of the vetch, and a high seed rate of the vetch. The last year of the project will include rice after the vetch in terminated this spring. We take soil samples each year in addition to looking at pest pressure from weeds. Greenhouse gas emissions are also being evaluated throughout the project, specifically before and after “events” such as rainfall, irrigations, fertilizations and tillage operations. Sarah Light (UCCE Agronomy Advisor), myself, and our grower cooperator ran a very successful field day in December 2018 about this project, cover cropping and soil health. Our 2019 field day included an equipment showcase (mostly related to planting and terminating cover crops) that led to great discussions among participants. We will hold our last field day in March 2020.  

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Processing Tomato Project Update

 

2019 was a big year for Fusarium diseases in the Sacramento Valley. I visited many fields with Fusarium wilt-like symptoms. 3 of these fields were positive for Fusarium wilt, with 2 positive for the new stem rot, Fusarium falciforme, and 1 tested positive for Fusarium crown and root rot. Other diseases encountered included Alfalfa Mosaic Virus, Verticillium wilt, Bacterial Canker, and Southern Blight. More information on diagnosing various wilts and crown rots can be found in the October 2019 Vegetable Crops Newsletter. 

Evaluation of weed control in tomatoes comparing finger weeders to standard cultivation

Organic growers rely on mechanical cultivators and hand hoeing to dislodge and remove weeds. The finger weeder, a mechanical weeder efficient at removing weeds from the crop row, is gaining popularity in the Central Valley. In 2019, I measured % weed cover before and after a pass with the finger weeder in organic tomatoes. Percent cover ratings for bare soil, broadleaf weeds, grass weeds, residue, tomato plants, and volunteer vetch (from cover crop) were assessed pre- and post-cultivation using 1m2 quadrats. Percent cover ratings were also done pre- and post-hand-hoeing. There was no significant difference between pre- and post- and weed counts, but there was very little weed pressure in this field. Cover crop residue was very high due to the wet spring and likely contributed to weed suppression early on. Weed counts remained very low through mid-June. The finger weeder continues to gain interest in the Sacramento Valley as another tool for weed management, especially for organic growers.

I would like my grower cooperators. This project was funded by the California Tomato Research Institute.

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Evaluation of Fusarium wilt survival in the Sacramento Valley as influenced by rotational crops of flooded rice and dry-farmed crops

Fusarium wilt, Race 3, Fusarium oxysporum f. sp. lycopersici, is a soilborne fungal pathogen damaging to tomato crops in the Sacramento Valley. In 2018, over half of the farm calls in Colusa and Sutter counties involved Fusarium wilt of tomato. The Sacramento Valley, especially the Sutter Basin, provides a unique opportunity to evaluate Fusarium wilt survival in rotations with flooded rice and dryland crops such as wheat and non-irrigated melons. While this disease is specific to tomatoes, little is known of the role rotational crops play in harboring Fusarium wilt in non-tomato years, especially rice. Though this project is meant to be long-term, in 2019 we tested the concept of placing inoculum bags filled with tomato plant tissue of Fusarium wilt, Race 3 in fields to monitor the pathogen over time under flooded  conditions.  

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We placed wire mesh bags with infected tomato stem pieces in a rice field and in a tomato field (as a positive control). Both fields had a history of Fusarium wilt, Race 3. Pathogen validation assays were conducted by the Swett Lab at UC Davis. No spore development was observed from any of the bags that were buried in the rice field. The bags buried in the tomato field ranged from 150-3,750 colony forming units per gram of Fusarium wilt tissue. Though no spore development is promising, this does not necessarily mean the disease will not develop once tomatoes are planted in the field again. The Sutter Basin has continued to see Fusarium wilt in tomatoes and they have been rotating with rice for years. The data collected from this project is just one part of a bigger picture of Fusarium wilt development in the Sutter Basin.

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This project was funded by the California Tomato Research Institute. Cassandra Swett-Field and Vegetable Crop Pathology Extension Specialist, Whitney Brim-DeForest-Rice Advisor, and Gene Miyao-Retired Farm Advisor, were my collaborators in this project. We would like to thank Dr. Kelley Paugh for her hard work conducting the lab assays and our grower cooperators, for allowing us to conduct this research in their fields. 

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.

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. A northern region (Colusa, Sutter, Solano, Yolo, San Joaquin and Stanislaus counties) meeting was held on March 28 in Davis, CA and a southern region (Merced, Fresno, Kings and Kern counties) meeting was held June 6 in Five Points, CA. The final document is currently being reviewed and will be published Spring 2020.

Principal investigators on this project include myself, Cassandra Swett-Field and Vegetable Crop Pathology Extension Specialist, and Tunyalee Martin-UC-IPM Associate Director for Communications. Collaborators include all UCCE Vegetable Crop Advisors and Specialists working on processing tomatoes/vegetables and the California Tomato Research Institute. This project is funded by the Western Integrated Pest Management Center.

 

Melon Project Update

 

Management of spotted and striped cucumber beetle in melon production

We evaluated 12 different insecticides for their efficacy against cucumber beetles on a research farm at UC-Davis. We based treatments on what is commonly used commercially plus newer insecticides untested in melons on cucumber beetles, including a seed treatment. 

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The seed treatment was not effective at reducing beetle numbers in the later season and because of low beetle pressure in the early season, we cannot comment on its efficacy. The standard insecticides used by melon producers (neonicotinoids and pyrethroids) resulted in the lowest beetle numbers post-application. The organic treatments were not significantly different from the untreated control in regard to beetle counts post-application. We did see differences in severity of damage between treatments and the standard conventional treatments protected melons from scarring damage by cucumber beetle feeding. Our organic treatments provided better control compared to the untreated plots, which suggests organic treatments may help reduce severe feeding damage and scarring.

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Additionally, we tested 3 different trap designs (all with a floral-lure attached) to find one that works best for catching cucumber beetles. Traps included sticky cards on top of a large yellow board to act as a visual stimulus, a Japanese beetle trap, and sticky cards alone. Across sites, there were no significant differences between the traps that included yellow sticky cards. The Japanese beetle traps were unsuccessful at all sites. Our trapping does not seem to affect beetle pressure in the field and could not serve as an attract-and-kill strategy. It does provide us information on the effectiveness of the floral lure and we will continue to use sticky card traps in our future studies to monitor for beetles. 

Ian Grettenberger, Field and Vegetable Crops Entomology Extension Specialist was a principal investigator on this project. Rachael Long-Field Crops and Pest Management Farm Advisor, and Margaret Lloyd-Small Farms Advisor were collaborators. This research was funded by the California Melon Research Board.

Other issues I received calls about included:

  • Fusarium falciforme on pumpkin
  • Fusarium crown and root rot, Fusarium wilt and southern blight on watermelon for seed
  • Squash mosaic virus on cantaloupe