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Gerry Spinelli Horticulture Advisor

Gerardo (Gerry) Spinelli is the new Production Horticulture Advisor serving the Nursery and Floriculture industry in San Diego. Gerry conducts applied research, extension, and education to improve viability and profitability of the Nursery and Floriculture industry, while conserving natural resources and complying with regulations. The Nursery and Floriculture industry in San Diego county is the first in California for volume of sales and the second in the US.

Gerry’s primary interests are irrigation management and water quality. These themes are a primary concern for growers given the high cost of water and the pressure from local and state water quality regulators. Nitrogen management is another of the advisor’s interests, given its strong relation to water management and its importance in the environmental impact of horticultural industry.

Pests, particularly invasive ones are another pressing issue for the industry. With the large volumes of ornamentals moving in and out from other states (primarily Florida and Hawaii), San Diego is particularly exposed to this threat.

Gerry is also interested in other themes unique to San Diego county, including urban agriculture and horticulture in the rural-urban interface and food deserts in low-income areas. Local growers face issues urban development encroaching into rural areas increasing the cost of real estate and the competition for water.

Nursery and Floriculture growers in San Diego county have shown the great ability to quickly react to these forces and adapt production practices to keep the industry profitable. Gerry’s primary concern is to conduct a research and extension program that serves the industry in present and future challenges.

Additional Information


My program focuses on water and nitrogen management in horticultural container production, hydroponics, and greenhouses. Water management includes improving the efficiency of irrigation water application, water distribution uniformity and correct scheduling of irrigation events. It also includes irrigation runoff, storm water management, nitrate and sediment management and erosion control. In nursery and floriculture production, the value of the crop is represented by its aesthetics. Producing beautiful plants requires high levels of water and nitrogen and production is often intensive. Nitrogen management becomes an issue given the high solubility of nitrate that can pollute groundwater and surface water bodies.

Because of the impact on the environment, these issues are regulated and are one of growers’ primary concerns. My role is to advise growers on management practices and regulators on policies. In both cases, I base my judgment on scientific evidence.


Ph.D. Horticulture and Agronomy, 2015 University of California, Davis

M.Sc. International Agricultural Development 2012 University of California, Davis

M.Sc. Tropical Agricultural Development 2008 University of Florence – Faculty of Agriculture

B.S. Agricultural Sciences and Technologies 2005University of Florence – Faculty of Agriculture

Professional Experience:

Visiting Scientist Aug 2018 – Feb 2019, University of Hawaii at Manoa – College of Tropical Agriculture and Human Resources Honolulu, HI. Duties included assisting extension agents in farm visits, teaching activities and workshops hydroponics, data analysis, mentoring undergrad students and implementing a project to test anaerobic soil disinfestation for banana Fusarium wilt.

Graduate Student Researcher, Oct 2010 – June 2015 University of California, Davis, Plant Sciences Department Davis, CA.

Research on impact of water stress on water use efficiency of almond orchards. through field experiments to measure photosynthetic rate, stomatal conductance, sap flow velocity and IR canopy temperature.

Scientific Contractor, Aug – Dec 2014 US Geological Survey, California State University, Sacramento Sacramento, CA. Processed greenhouse emission data from a flux tower using the eddy covariance technique as part of a 3-year study measuring greenhouse emissions from four wetlands in California.

Beekeeper, May-Jul 2010. La Poggiata Beekeeping, Florence, Italy. Apiary management swarming control, queen rearing, honey harvesting and extracting, pest and disease monitoring, organic varroa treatment application.

Project Manager, May 2009 – May 2010 Italian Development Agency, Italian Embassy Baalbek, Lebanon

Managed an irrigation system construction project ($1,000,000) delivering water to 1,600 acres and 250 growers. Developed agricultural training programs for irrigation and nutrient management. Supervised construction of sewer lines and well water quality improvement project for the Wavel Palestinian camp. Developed advanced beekeeping training program.

Landscape Irrigation Technician Mar - Oct 2008 The Landscape Garden Co, London, UK

Designed and installed landscape irrigation systems, landscape construction work and public park maintenance.

Extension Service Intern, Jul – Dec 2007, Italian Development Agency, Italian Embassy, Tegucigalpa, Honduras. Provided field technical assistance for farm irrigation system construction and water management as part of the community outreach activities of a 550 acres irrigation system project.

Recent Presentations

Principles of irrigation, San Diego Master Gardener Program, San Diego, CA, Jan 2021

Management of Runoff in Agriculture San Diego Farm Bureau Wednesday Webinar, Nov 2020

Promoting the Adoption of Soil Nitrogen Quick Tests by Spanish-speaking Operators on Strawberry Ranches in Santa Cruz and Monterey Counties, CDFA Fertilizer Research and Education Program Conference, Oct 2020

The use soil nitrate tests to drive fertilization decisions (in Spanish), Reiter Inc., Watsonville, CA, Feb 2020

Soil nitrate quick test and their use on CropManage, CropManage workshop, Watsonville, CA, Nov 2019

Nitrogen management in strawberry production, CDFA FREP workshop, Watsonville, CA Oct 2019

How to collect process and interpret a soil nitrate quick test (in Spanish), ALBA, Salinas, CA, Sep 2019

Pre-plant slow-release nitrogen fertilizer evaluation in strawberry, ASHS annual conference, Jul 2019

Proyecto de asistencia para regadores, PVWMA irrigator annual meeting, Watsonville, CA, Mar 2018 and 2019

Wild Animal Deterrent Field Day for FSMA, UH CTAHR Waimanalo Research Station, Oahu, Dec 2018

Field Q&A: Growing Mamaki Commercially. Hawaii Farmers Union United, Haleiwa, Oahu, Nov 2018

Pest Management for HI-NexGen Small Farmers. UH CTAHR Waimanalo Research Station, Oahu, Oct 2018

Pajaro Valley BMP Agricultural Water Conservation Program Update, PVWMA Board Meeting, May 2018