South Coast Research and Extension Center
South Coast Research and Extension Center
South Coast Research and Extension Center
University of California
South Coast Research and Extension Center

Tree Crops


76 – Avocado Germplasm Collection

Principal Investigator: Dr. Mary Lu Arpaia, Botany and Plant Sciences Department, University of California – Riverside. For more project information, click here.

The avocado variety germplasm block contains nearly 200 varieties that have historical significance to the development not only to the California avocado industry but to the international industry as well since many of the commercially grown varieties today originated in California.  These materials are used for demonstration purposes for the public as well as seed source for the variety development program.  In addition, we have a small planting of relatives of the avocado, Persea Americana, included in the collection.  These materials are provided upon request to researchers within the United States and have been used in screening for resistance to exotic pests such as the Red Bay Ambrosia Beetle and its fungal symbiont, Raffaelea sp., which causes laurel wilt, as well as the Polyphagous shot hole borer (Euwallacea sp.) and its fungal symbiont, Fusarium sp.

90 – Avocado Diseases

Principal Investigator: Dr. Akif Eskalen, Plant Pathology and Microbiology Department, University of California – Riverside. For more project information, click here.

South Coast is the main location for our avocado rootstock and development program which is conducted in close association with the California Avocado Commission. Most of our avocado germplasm is maintained here. The germplasm kept here allows us to select and breed new avocado rootstocks which have resistance / tolerance to avocado root rot, tolerance to salt or are potentially dwarfing. Ultimately, the control of avocado root rot will be accomplished with a resistant rootstock. The project has already provided the industry with several new tolerant rootstocks, which are greatly improving the yields of avocado on land infested with Phytophthora cinnamomi. The goal is to find a rootstock that will eliminate Phytophthora cinnamomi as a serious pathogen on avocado. Our ability to find such a rootstock has been enhanced as a result of our breeding blocks where we focus on crossing already resistant rootstocks.


93 – Avocado Breeding

Principal Investigator: Dr. Mary Lu Arpaia, Botany and Plant Sciences Department, University of California – Riverside. For more project information, click here.

Project 93 Avo Breeding
This project addresses 2 major research objectives of the California avocado industry (as outlined in the California Avocado Commission annual RFP):

  • Development of new avocado varieties through plant breeding, selection and evaluation of potential cultivars from growers and nurserymen throughout the avocado regions of the world. We are emphasizing selections for productivity, fruit quality, adaptation to California conditions, and disease and pest tolerance, tree growth habit, market acceptance and optimal maturity timing for market positioning.
  • Improving pollination of the avocado through selection of pollinizer varieties for improved fruit set and yields through field testing and the use of genetic markers.

The site at South Coast REC is the major research site for this project and supports and provides material for our statewide efforts. We re-initiated the selection process in 2000 by the planting of new isolation plots at UCR and in Ventura County. Additionally, following an external review in 2005 of the program we have expanded the maternal selection block located in Field 4 at the REC. Renovation of this block continues and will serve as the underpinning of the program in future years.


210 – Citrus Relatives

Principal Investigator: Dr. Tracy Kahn, Botany and Plant Sciences Department, University of California – Riverside. For more project information, click here.

Preservation of citrus genetic resources, including related genera, is essential due to the loss of this genetic diversity in native habitats and the difficulty of obtaining germplasm from other countries where it is seen as a commodity that should benefit the nation in which they occur. The need for a well characterized ex-situ collection becomes more important as the potential risk of citrus diseases such as Citrus Greening Disease threaten California and other commercial citrus industries.  There is evidence that certain citrus relatives may have resistance and/or tolerance to this disease and others that exist outside California.  The Citrus Relatives Project at SCREC in Blocks 24 and 25 is part of the UC Citrus Variety Collection, one of the world's most diverse collections of citrus and related taxa that includes over 1000 accessions within 29 genera of the subfamily Aurantiodeae within the Rutaceae family. The principal location of the Citrus Variety Collection is at UC Riverside, with a supplemental planting at SREC. We are continuing efforts to preserve trees of various frost-sensitive citrus relatives at this comparatively frost-free site for research and extension activities at SCREC. This project provides a resource for distribution of seeds by the USDA National Clonal Germplasm Repository for research throughout the world and provides a resource for research in the U.S. to evaluate citrus relatives for selected reproductive and vegetative traits and tolerance and/or resistance to Citrus Greening Disease in Florida.


164 – Pitahaya Research and Variety Evaluation for Commercial Production

Principal Investigator: Dr. Ramiro Lobo, Small Farms and Agricultural Economics Advisor, UC Cooperative Extension. For more project information, click here.

Project 64 Pitahaya
Pitahaya, or Dragon Fruit, (Hylocereus spp. and Selenicereus megalanthus) is a vining cactus native to tropical America and commercially grown in several countries. Pitahaya is already established and grown as a backyard plant in San Diego and other counties in California for its edible fruit. The fruit is especially popular among people from Southeast Asia and Latin America for fresh consumption or for special events. However, despite the growing demand and popularity of the fruit, local supply is almost non-existent. This, combined with bans on imports of fresh pitahaya fruit into the US has created considerable interest among growers and specialty produce marketers increasing the potential for a commercial pitahaya production industry in southern California and an attractive crop alternative for local farmers.

This research project aims to develop production, economic and marketing information that may lead to the commercial production of pitahaya or dragon fruit by small-scale farmers in San Diego and other counties in Southern California. Plant material from eighteen commercially grown varieties or clones of pitahaya identified as self-fruitful was used to establish a field trial to evaluate their performance under growing conditions in Southern California. 2008 was the second data collection year for the project and first for some varieties in our trial. All varieties have adapted relatively well to growing conditions in Southern California. However, there are marked differences among the varieties with regards to susceptibility to frost, sunburn, and in overall yield and fruit quality. Although results are not final, the project has provided much needed information for the establishment and growth of a pitahaya industry in California. 

211 – Extension Blocks

Principal Investigator: Dr. Darren Haver, Director, UC ANR South Coast Research and Extension Center. For more project information, click here.

UCCE Master Gardener sharing a pummelo
The purpose of this project is to provide a space for extension projects for use by the center and affliated organizations. Currently, we have blocks set aside for citrus, fig, persimmon, stone fruit, avocado, and apple trees. With the UC Cooperative Extension Master Gardeners of Orange County, we will continue to make these areas available for demonstrations, interpretive displays, and extension events.

Additional Information:

Evaluation of Pluots and Apples

Pluots are complex interspecific hybrids of plum and apricot (Prunus sp. L. X Prunus armeniaca L.). The sugar content of a pluot fruit is reported to be much higher than either of its antecedents. These delicious new type of fruit provide new opportunities for tree fruit growers. We are evaluating 5 moderate-chill pluot cultivars on Myrobalan 29C rootstock in a trial at South Coast Research and Extension Center. A second trial evaluates the performance of Flavorich cultivar on Citation rootstock compared to Flavor Grenade cultivar on Lovell rootstock. The cultivars continue to be evaluated for adaptability, yield, fruit quality and for susceptibility to pests and diseases.

Trees were planted in 2-tree plots, replicated five times in a randomized complete block design and the orchard managed following recommended cultural practices typical for plums. Specific data to be collected from the trials include tree trunk cross sectional area, fruit set, total marketable fruit number and weight, average fruit weight, fruit diameter, % TSS (total soluble solids) and panel taste scores. All data will be subjected to ANOVA and mean separation between treatments done by an appropriate test.

The results of this research will be disseminated to members of the California Rare Fruit Growers Association, production nurseries and on field days and group tours of South Coast REC. Poster and oral presentations at various meetings as well as papers in professional publications will be additional avenues for extending results from this trial.

230 - Coffee (Coffea spp.) Variety evaluation for Ornamental and Commercial Production in Southern California

Principal Investigator: Dr. Ramiro Lobo, Small Farms and Agricultural Economics Advisor, UC Cooperative Extension. For more project information, click here.

Coffee ranks second only to oil as the most traded commodity in the world and is the primary agricultural export for many countries. Coffee (Coffea spp.) is native to Africa where an estimated 100 species are found in diverse geographic and climatic regions. Coffee species vary greatly depending on the region and climate where they originate, resulting in various coffee types with different genetic make-up, different morphological traits (size and shape of plants, fruits, and growing habits), flavor profiles, tolerance to pests and diseases, and tolerance to drought. Coffee plants adapt and grow well in frost-free microclimates in California from San Luis Obispo to San Diego County. Coffee plants are commonly grown as ornamentals by backyard growers and California Rare Fruit Growers, but there is no history of commercial coffee production anywhere in the continental US. Specialty coffee consumption and the demand for specialty coffees have increased dramatically in the US and the world over the past several years. This trend, combined with increased demand for high value, differentiated agricultural products (local or California grown) and declining profit margins for existing crops, has generated a strong interest in the production of specialty coffee among farmers in Southern California. However, research-based information on coffee propagation, growing, production or variety performance is needed for Southern California residents and growers interested in coffee as an ornamental plant or a commercial enterprise. This project will develop research based information and demonstrate coffee propagation techniques, evaluate 18 varieties of coffee, and assess the potential for grafted, drought tolerant coffee plants for ornamental uses or commercial production in Southern California.

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