Subtropical Fruit Crops Research & Education
University of California
Subtropical Fruit Crops Research & Education

Posts Tagged: oranges

Invasive Scale?

Recently a grower called up with a beautiful scale that the PCA couldn't identify.  I could just marvel at the beauty of it and wondered what in the heck it was. It didn't look like any scale I had seen in the area and others who were queried didn't know either.  

I took it into the Ag Commissioner's office and they sent it off to see if it was a new species. Images were sent off to various entomologists and David Haviland in Bakersfield identified it as a Ceroplastes, possibly a Chinese wax scale or Barnacle scale.  Others had identified it as Florida wax scale.

 It was sent into Paul Rugman-Jones at UC Riverside Entomology for DNA identification.  His identification and that of CA Dept of Food and Ag entolomogists came back as Barnacle scale, Ceroplastes cirripediformis.


All of these scales turned out to have been seen in California before, so there was no quarantine issue.  It also turned out that all of the adults that were turned in for identification had also been parasitized by some wasp.  So there is biological control already in place for it.  The issue at stake here, though, is that it's important to be watching for new visitors in the orchard.  Joe Morse now retired from UC Riverside Entomology lead a team that intercepted avocados coming into the US.  They found a number of scale insects that were new to California and new to the identification world.  A number of these scale are parthenogenic, meaning they can reproduce without males, and just one lone female could possible balloon into a massive population in a short time.  And on a scale like that, trees would have a hard time without some serious intervention.

Posted on Friday, September 29, 2017 at 6:46 AM
Tags: avocado (289), biological control (4), citrus (338), grapefruit (27), invasives (12), lemon (100), lime (5), oranges (6), pests (25), scale (10)

Citrus Grower Meeting Coming Soon

Every year growers get together to learn what is being done in the citrus research world that could affect their operations. This June, University of California and the Citrus Research Board are bringing some good talks to three different growing areas. All growers are invited, but RSVPs are appreciated.


CRB-GrowerSeminar-Flyer 2017
CRB-GrowerSeminar-Flyer 2017

Posted on Friday, May 19, 2017 at 6:13 AM
Tags: ACP (86), alternate bearing (5), breeding (4), citrus (338), disease (57), fertilizers (6), grapefruit (27), huanglongbing (66), irrigation (79), irrigation (79), lemons (9), mandarins (5), nutrition (5), oranges (6), pests (25), tangerines (1)

New Avocados for the Valley?

California avocados are the best in the world. So says downtown restaurant manager Daniel Avalos in a Valley Public Radio story by reporter Ezra David Romero.

The fact that they currently thrive only on a small swath of coastal Southern California is being challenged by UC Cooperative Extension specialist Mary Lu Arpaia. She is on a mission to find avocado varieties that withstand the hot summers and cold winters of the San Joaquin Valley, where irrigation water and crop land are more abundant and cheaper. 

She hopes to find avocado varieties that ripen at various times of year, and varieties that might be an alternative crop for citrus growers should huanglongbing, a disease that has devastated the Florida citrus crop, take hold in Central California.

"There's a void of California fruit on the market in the months of November, December and actually early January," Arpaia said. "So if we can find different selections that maybe are unique that fit into that window, then we help the entire California avocado industry."

An as-yet unnamed avocado variety. 

Romero visited the UC Lindcove Research and Extension Center to see the trees in Arpaia's study. Currently, the vast majority of California avocados are the Hass variety. The goal is to breed varieties with similar eating quality that grow to a moderate height and have high yield. One potential that is already being produced by nurseries is called "gem."

"This is gem," said Eric Focht, a staff research associate in Arpaia's lab. "You can see it's a little more oval or egg shaped than Hass. It has the speckling on the skin. Now as this ripens, it will turn dark and a lot of times the speckled lenticels with get a yellow kind of golden color it it."

Another promising variety is called "lunchbox" because of its small size. According to Focht, it "just falls out of the skin." Arpaia said, "It makes wonderful guacamole and I found, with a non-replicated test in my refrigerator, the fruit doesn't brown."

Arpaia's favorite guacamole recipe is featured at the end of the story on the KVPR website. And there is more on this story at:


Mary Lu Arpaia

Mary Lu
Mary Lu

Posted on Friday, May 12, 2017 at 5:46 AM
  • Author: Jeanette Warnert
Tags: avocado (289), California (13), citrus (338), freeze (10), frost (19), heat damage (4), irrigation (79), lemon (100), new crops (6), new variety (1), nutrients (21), nutrition (5), oranges (6), temperature control (1)

Citrus Tasting at Lindcove

Well it came again, the Citrus Tasting at Lindcove Research and Education Center in Lemon Grove near Exeter, close to Visalia and just down the road from Fresno and up from Tulare.  They came, growers to see and taste new and old varieties. And then the next day, the general public with oooos and ahhhs to taste the range of flavors we call citrus.  Big fruited pummelos and little fruited finger limes.  Sweet, sour, not sweet, not sour, dull, and boing!.  Growers came on Friday morning and the general public the following Saturday.  It was crowded both days.

Citrus is wonderful, everyone knows, but it is also under dire threat of Huanglongbing and the potential destruction of this industry and the trees that are found in many backyards. So in a completely unscientific survey, I asked growers why they were there if their world was about to end.  First of all, those who showed up were already optimistic about the future, so there was already a self-selection.  But, growers felt like a solution would be found, science would find an answer.  Driving across the Valley and through coastal counties like Ventura there are lots of new plantings......if there's water.  But it's surprising how confident growers are about finding a solution.  There are some hopeful signs out there like the new rootstock release from USDA of US-1516 which shows a lot of tolerance to the disease.  Then there is the potential of disease tolerance in a citrus produced in Florida from a collaboration of Southern Gardens, USDA and a consortium of Universities.  Yes, there is hope, but years are still needed to test and gear up for production for commercial applications.

So it was good to be around growers who have an enthusiasm for the future and looking for new planting varieites.


And they are both grapefruit, one is Melogold the one on right is Oro Blanco

Buddha's Hand citron

The Citrus Display at Lindcove Research and Extension Center, before the crowds

Melogold and Oro Blanco
Melogold and Oro Blanco

IMG 1965
IMG 1965

citrus display
citrus display

Posted on Wednesday, December 16, 2015 at 8:25 AM
Tags: ACP (86), Asian Citrus Psyllid (57), citron (3), citrus (338), grapefruit (27), haunglongbing (2), HLB (71), lemons (9), oranges (6), pummelos (1)

Area-wide Asian Psyllid Treatments in Ventura

On Aug. 30, Ventura County's citrus growers, pest-control advisers (PCAs) and pest-control operators (PCOs) embarked on the most ambitious program of Asian citrus psyllid suppression in commercial groves ever undertaken in California. The program involves coordinated pesticide treatments across more than 15,000 acres of citrus in the Santa Clara, Las Posas and Santa Rosa valleys. Hundreds of growers, PCAs, PCOs, grove managers and packinghouse field staff — aided by our county's two grower liaisons and the local ACP-HLB Task Force — are working together to pull it off.


This is the second cycle of area-wide management (AWM) treatments in Ventura County. The first was carried out from January through March in the east end of the Santa Clara River Valley. It involved eight of the county's 49 psyllid management areas PMAs and achieved good compliance, with 87 percent of the total acreage being treated (the rate within individual PMAs ranged from 80 percent to 93 percent).


The current cycle, however, involves 36 PMAs, vastly increasing the program's complexity. It also increases the workload for our PCAs and PCOs, and amplifies the consequences of any disruption in the timetable, which requires that all the citrus in each PMA be treated within a narrow two-week window.


And disruptions are precisely what the program has encountered. The extended periods of extreme heat that have cooked the county over the past two months have idled equipment and crews. At the same time, explosions of other pests — particularly broad mite, flaring under the unusually tropical conditions — have diverted resources to non-ACP treatments to avoid immediate economic harm from damaged fruit.


It remains to be seen whether the crews will be able to get back on track, and finish the fall AWM cycle by the end of November as planned. There is also the chance the applicator crews will encounter further delays, either in the form of extreme heat, Santa Ana winds or early rains associated with the strengthening El Niño condition in the Pacific.


As I have reminded members of Ventura county's citrus community numerous times since we began planning the transition to AWM, our program at this stage is a huge experiment with statewide ramifications.


We can't really draw lessons from areas outside California that are attempting area-wide suppression efforts (Texas and Florida) because their circumstances are so different. We have different weather and topography, for one thing. And Florida in particular did not even try to control ACP until most of the state was also infected with Huanglongbing (HLB) disease, so their program has struggled from the start. Our landscape is also quite different, with none of the giant citrus plantations of Florida and a much more complex pattern of intermingled smaller orchards and urban development than anything seen there or in Texas.


We also have little in common with the few other areas in California that are trying to implement AWM (mainly portions of Imperial and San Diego counties) because we have far more acreage and a much greater number of growers. Eventually, the San Joaquin Valley will find itself implementing AWM, at which point California will finally have an AWM program exceeding ours in scale. The very slow pace of ACP detections there, however, suggests that day is still well in the future.


For now, we have to figure out what works — and what doesn't — on our own. Trying to craft policies and protocols while also attempting to implement them is a bit like trying to build a race car while speeding down the track at 200 mph, but we have no other choice. Think of it as “adaptive management” on steroids.


There have been some very productive discussions among members of the Ventura County ACP-HLB Task Force and our hard-working PCA/PCO community, identifying data needs, logistical constraints and strategy options so we can continuously refine and improve the program. One of our chief challenges is adjusting for our equipment and spray crew limitations while still achieving effective ACP suppression, even when the weather and other pests refuse to cooperate.


One piece of very good news that has emerged at the midpoint of our fall AWM cycle is that the California Department of Food and Agriculture has been conducting timely treatments in urban yards within 400 meters of commercial citrus in each PMA. That did not happen last winter, and the result was swift re-infestation of commercial groves from ACP populations in neighboring landscape plants. At our request, and to CDFA's credit, the agency changed its policy and is no longer waiting to determine the level of grower participation before commencing those treatments.


Countering that, however, are scattered reports of growers refusing to participate — some even going so far as to switch packinghouses in order to avoid the policy instituted by responsible houses to suspend picking and packing fruit from an orchard during the PMA treatment window until the treatment has been conducted.


Evading the treatment requirement is irresponsible and fatally short-sighted. We know for a fact that HLB is less than 50 miles from us, and we also know for a fact that ACP from areas to the south — potentially even infected psyllids — is being transported into Ventura County in loads of bulk citrus. Just recently, a psyllid that tested “inconclusive” for HLB — neither positive nor negative — was collected in Piru. It may be a false alarm, and additional testing of psyllids at the same site will be conducted, but when clusters of such ACP have been found in the past, they have indicated locations where trees soon test positive for the disease.


Holdouts in the Ventura County citrus community must stop thinking of the ACP campaign as a battle against a bug, like so many other battles the industry has fought and won in the past. It is not. Ventura County citrus has never before confronted a tree-killing, insect-vectored disease epidemic, and the tools and strategies of conventional pest management will not stop or control it.


Save the date


To help Ventura County's citrus community better understand the nature of the epidemic — and the bitter lessons from Florida's failure to address it proactively — Farm Bureau and the ACP-HLB Task Force will host a workshop on Dec. 2. As speakers, we've invited three experts whose presentations were among the most compelling at last February's International Research Conference on HLB in Florida:

  • Mike Irey, director of research and business development for Southern Gardens Citrus (which farms nearly 15,000 acres of oranges in Florida), who will speak about conditions in his state and provide an industry perspective on what it's like to live with HLB for a decade;
  • Dr. David Bartels, an entomologist at the U.S. Department of Agriculture's Mission Laboratory in Texas, who will discuss his analysis of HLB survey data and what it can tell us about possible HLB infection sites throughout Southern California;
  • Dr. Neil McRoberts, an epidemiologist and associate professor of plant pathology atUC Davis, whose computer modeling and research into the economic and social factors affecting disease spread can help guide development of an HLB management strategy for California.


The workshop will be from 1 to 4 p.m. on Wednesday, Dec. 2, at the Museum of Ventura County, 100 E. Main St., Ventura. It's free, but RSVPs are required. Please contact us at or (805) 289-0155 if you plan to attend.


— John Krist is chief executive officer of the Farm Bureau of Ventura County. Contact him at

ACP nymph wax
ACP nymph wax

Posted on Tuesday, October 27, 2015 at 4:46 PM
  • Author: John Krist
Tags: grapefruit (27), huanglongbing (66), lemons (9), limes. psyllid (1), mandarins (5), oranges (6)

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