- Author: Jeannette E. Warnert
Southern California's mild Mediterranean climate makes it ideal for growing fruit trees in backyards, community gardens and school gardens. The trees provide wholesome fruit along with shade, beauty and enrichment for families and communities.
Citrus trees are favorites for Southern California backyards, but Surls and her team aim to get local gardeners thinking beyond lemons, limes, oranges and other citrus fruit. In the past several years, a deadly plant disease has been spreading among Southern California citrus, prompting quarantines and putting citrus orchards across the state at risk.
Surls and her team are working on an initiative with a corps of volunteer UC Master Gardeners in Los Angeles and surrounding counties to promote selection and planting of appropriate fruit trees. New brochures, a website, workshops and one-on-one consultations will guide Southern Californians in making tree decisions that are scientifically sound and community-focused.
The project addresses serious concerns about the rapid spread of huanglongbing (HLB) disease, also known as citrus greening. The insect that spreads HLB – the Asian citrus psyllid – was introduced into California in 2008. The disease made its first California appearance in a Los Angeles County backyard in 2012. HLB, which eventually kills every tree it infects, is now spreading rapidly in urban areas of Los Angeles and Orange counties, where quarantines have been put in place by the California Department of Food and Agriculture (CDFA).
“Citrus trees are so popular in Southern California. They are part of our history and regional identity,” Surls said. “Now we have the unfortunate responsibility of telling residents about this serious problem we are facing. In some cases, residents who live near infected trees should be proactive and remove their lemon, orange, mandarin and lime trees and replace them with different kinds of fruit.”
University of California Agriculture and Natural Resources IGIS programmers, in collaboration with UC Cooperative Extension, have created an HLB Monitoring Web App that allows residents to enter an address to determine how close they are to confirmed HLB outbreaks. If they are within 2 miles of a residence where an HLB-infected citrus tree was found, the app recommends replacement of citrus trees with non-citrus fruit trees, such as apples, peaches, avocados or persimmons.
Residents with citrus trees that are 2 to 5 miles from areas with HLB should keep a close eye on their trees, treat for Asian citrus psyllid and begin thinking about planting an alternative to citrus if the disease spreads to their area.
“Huanglongbing poses a serious threat to both backyard and commercial citrus in California if its spread is not halted,” Surls said. “By removing trees in areas where HLB has been found, residents are helping reduce its ability to spread, buying time for scientists to find a cure.”
CDFA is testing trees throughout the state and removing HLB-infected trees. However, the first visible symptoms of HLB – yellow mottled leaves – can appear months to years after infection. Even if they look perfectly healthy, citrus trees can be harboring the disease and allowing it to be spread by the tiny psyllid insect.
Current hotspots shown on the HLB Monitoring Web App include Rosemead, Montebello, Pico Rivera, San Gabriel, Hacienda Heights and Cerritos in Los Angeles County. In Orange County, HLB is spreading in communities around Garden Grove, Westminster and Santa Ana.
“We know removing citrus trees is going to be really hard for people,” Surls said. “But if you live within two miles of an infected tree, your tree is probably already infected, and HLB means your tree is going to die.”
To ease the transition, UC Master Gardeners are informing residents about alternatives that will produce fruit that's nutritious and delicious.
“So many types of fruit trees can be grown in Southern California,” Surls said. “Honestly, we have almost unlimited options. We live in a fruit tree grower's paradise. So we want to encourage local residents to think seriously about selecting non-citrus trees to replace their citrus.”
The information can also inform residents who are planning a new backyard orchard.
“They should consider some of the many wonderful fruit trees we can grow here — plant a pomegranate, plant a peach, plant a persimmon — but resist the temptation to plant more lemons, oranges and other citrus trees,” Surls said.
Making the decision to plant a certain type of tree should not be taken lightly.
“Planting a fruit tree is a big commitment. It will be part of your garden for years. Research the best options for your family and locations,” Surls said. “The UC Master Gardeners are here to help.”
Following are good options to consider for replacing citrus trees in Southern California, although recommendations may vary based on local climate:
Certain apple varieties that do not need to be exposed to cold temperatures grow and produce well in Southern California. Low-chill varieties include Anna, Beverly Hills, Dorset Golden, Fuji and Gala.
Figs grow well in full sun in Southern California. They can reach 10 to 30 feet tall, and are best for spacious areas.
Jujubes are less common in Southern California, but are a valued fruit in Southeast Asian and will grow well under Southern California conditions. They grow about 15 feet tall. Jujubes are a good selection for inland valleys that get hot during the summer. The fruit tastes like small, crispy apples. Dried, they are similar to dates.
A small- to medium-size tree that grows 10 to 20 feet high, loquats are easy to grow and have relatively few pests. Fresh, ripe loquats are sweet and aromatic. They can be used in jams, sauces and garnishes.
Persimmons ripen in autumn after the leaves have fallen, creating a beautiful landscape display. They are easy to grow in full sun and part shade. Persimmons can be eaten fresh or dried for a date-like fruit.
Well-suited to Southern California's Mediterranean climate, pomegranates grow to about 15 feet in height. Pomegranates are pest- and disease-resistant. The fruit's seeds, coated with astringent juicy flesh, are called arils. Use arils to top salads or other dishes, or squeeze for juice or to make jelly.
Other fruit tree options for Southern California include mangos, guavas, pineapple guavas, peaches, nectarines and pears.
For more research-based information about alternative fruit trees, visit the UC Agriculture and Natural Resources website “California Backyard Orchard” at http://homeorchard.ucanr.edu.
Contact your local UC Master Gardener Program for additional advice:
Los Angeles County – http://celosangeles.ucanr.edu/UC_Master_Gardener_Program
Orange County – http://mgorange.ucanr.edu
Riverside County – https://ucanr.edu/sites/RiversideMG
San Bernardino County – http://mgsb.ucanr.edu
Ventura County – https://ucanr.edu/sites/VCMG
Funding for the ‘Alternatives to Citrus Fruit in the Fight against Huanglongbing Disease' project was made possible by the U.S. Department of Agriculture's (USDA) Agricultural Marketing Service through grant AM180100XXXXG003. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA.