Information about clean citrus trees, and Huanglongbing, a deadly disease for citrus
I had an inquiry from Dick Kirk of the Redwood Empire chapter of the California Rare Fruit Growers (CRFG), preparing for the upcoming Scion Exchanges, wanting educational resources for Huanglongbing, the most devastating citrus disease known. Let’s be clear: trading backyard citrus budwood can spread this disease, and is not legal to do so in the state of California. If you think this is ‘no big deal’, just talk to anyone trying to grow citrus in Florida- they will tell you a very, very sad story.
First some background on HLB, then clean citrus tree sources, with more resources on identification and reporting at the end:
Huanglongbing (HLB), also known as ‘Citrus Greening’ and ‘Yellow Dragon’, originated in Asia, with various strains spread throughout the world. It is a vascular disease fatal to citrus trees, which is caused by a difficult bacteria to culture (Candidatus Liberibacter asiaticus), and is associated with it’s vector: the Asian Citrus Psyllid (ACP). HLB was first discovered in the U. S. in 2005 in Florida, were it has devastated thousands of acres of commercial citrus orchards, and backyard trees. Infected trees may show no symptoms for years while still being a source of infection for other trees. Once symptoms show (see below) the tree may have only three to five years to live. HLB is now found in Florida, Louisiana, Georgia, South Carolina, and now recently in California- found in only one tree near Los Angeles. This infection has been traced back to a casual graft of infected citrus scion smuggled in from Asia, traded by backyard growers.
The Asian Citrus Psyllid (ACP), Diaphorina citri, is the only known vector for HLB (besides humans), and has been found in eight Southern and Western states. The United States Dept. of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS) regulates the movement of plants from infected states, and the California Dept of Food and Agriculture (CDFA) regulates the movement of plants from infected counties within the state. ACP is well established in Southern California’s quarantined areas, also being hosted by many citrus related species, so we should all be on alert.
Let’s do our best to follow the quarantine restrictions on citrus related plants from Southern California, source and propagate only certified disease free plants, rootstocks and scions, and keep vigilant for ACP and HLB on our own trees here in Northern California. See resources for what symptoms to look for, below. But first, here are some clean sources of citrus plants:
We have great local (Nor. Calif.) wholesale citrus nurseries to get clean citrus trees from:
(many local retail nurseries sell trees from these growers)
Four Winds Growers, http://www.fourwindsgrowers.com. The Dillon family has been in the business for fifty years and three generations, offering a really great selection of varieties. They are famed for originating and popularizing semi-dwarf citrus trees for back yard growers, and for discovering ‘Improved Meyers’ lemon, a virus-free clone of ‘Meyers’. They have expanded over the last few years beyond their grounds in Fremont, with additional operations in Watsonville and Winters. This year they have a new team member: the energetic and knowledgeable fruit enthusiast, Ed Lavio.
Menlo Growers- http://menlogrowers.com/, has been located in Gilroy for thirty years, growing many types of fruit trees, including an excellent variety of citrus, including large, ‘specimen-size’ trees.
If you want to start your own trees, order rootstock in bulk from a certified nursery, like:
B & Z Nursery Inc., 1850 S. Newcomb, Porterville, CA, 93257
Phone: 559. 781.7438, Fax: 559.781.6493. No website, but I have had good experience with them.
TreeSource Citrus Nursery http://www.citrustreesource.com/, or
The largest selection of certified citrus budwood:
University of California Riverside’s Citrus Clonal Protection Program (UCR CCPP), http://ccpp.ucr.edu/
This collection is now actually maintained in protective screenhouses at UC’s Lindcove Research and Extension Center, Exeter- where the tasting is this weekend. It is best to consolidate orders with your local California Rare Fruit Growers chapter members, and submit a larger, collective order. It will be less handling for the CCPP, and you will be able to make the minimum numbers of buds that are required, with less shipping costs. UCR also has it’s own page on ACP/HLB- http://cisr.ucr.edu/citrus_greening.html
Here are my favorite sources of information about the vector and disease- ACP/HLB:
The California Department of Food and Agriculture (CDFA) and the Citrus Research Board have the best information for California
CDFA Plant Health and Pest Prevention Services,
Pest Hotline: 1-800-491-1899
Asian Citrus Psyllid/Huanglongbing webpage,
general and detailed maps of quarantine areas, official press releases, lots and lots of info!
Quarantine maps for California:
ACP/HLB Multimedia Page- fact sheets, photos, posters, news articles
For ready to print pdf’s of Flyers, ID Cards, Bookmark, and more Links from the CCPP: http://ccpp.ucr.edu/news/HLB-ACPs-ANR-Educational-7-20-07.html
Citrus Research Board is an industry group that is funding much research into combating ACP and HLB
if you want ready to print pdf’s of fliers in 11 different languages, and the bookmarks also in Spanish see this page:
Save our Citrus (USDA APHIS) http://www.saveourcitrus.org/ info is not very detailed. Great graphics to catch people’s attention, and to get them the basics- like the one at the top of this post!
They do have the national info on ACP/HLB’s spread in other states, but their hottest tool is their iPhone app to identify and report ACP/HLB:
There are many more technical sources of info if you just take some time with your internet search engine.
Enjoy this citrus season, and practice safe plant propagation. Watch for upcoming (clean) citrus grafting workshops.
As fellow CRFG stalwart Karl Gross signs his emails: