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

Topics in Subtropics Blog

Which Way HLB - Huanglongbing and Asian Citrus Psyllid? Now in Marin.

The best way to delay arrival of HLB in our area and minimize its impact is to keep ACP suppressed down to the lowest level possible.  By treating in coordination with neighbors in an areawide approach, grower ACP treatments can have a greater impact on ACP populations than treating independently and out of sync with neighbors. Best Management Practices, such as making sure all equipment arriving and leaving your grove is free of citrus stems and leaves, can also greatly reduce the risk of HLB-positive psyllids entering your grove.

CITRUS REMOVAL PROGRAM: Citrus trees that are neglected or abandoned may harbor ACP and HLB, increasing risk to other citrus in the area. Abandoned and neglected trees may be reported to Cressida Silvers at 805-284-3310,  or the county Ag Commissioner's office. The Citrus Matters ACT NOW program may be able to assist in citrus removal. For more information contact Joel Reyes at  jreyes@cacitrusmutual.com or (559) 592-3790. 

Asian Citrus Psyllid / ACP

There have been no ACP detections in San Luis Obispo County since our last update.

Huanglongbing / HLB

The most recent map and totals for HLB detections are posted at the website https://citrusinsider.org/maps/. As of November 16, the total number of trees that have tested positive for the HLB bacterium is 948, still all in LA, Orange, and Riverside Counties. All HLB detections have been on residential properties and the infected trees have been or are being removed. No HLB has been found in commercial groves to date.

Clarification on Field Cleaning Requirements for Movement of Bulk Citrus

To clarify the approved mitigation measures for bulk citrus fruit movement, the California Department of Food and Agriculture (CDFA) has updated the Asian Citrus Psyllid (ACP)-Free Declaration form. The current options that allow growers to meet the ACP-free standard when shipping fruit to a different ACP regional quarantine zone are the “spray and harvest,” “field cleaning with machine” and “wet wash” methods. Field cleaning must be done by machine, not by hand.

To read the full article, click here: https://citrusinsider.org/2018/11/clarification-on-field-cleaning-requirements-for-movement-of-bulk-citrus/

Upcoming CPDPC Meetings

  • Joint Science and Technology Subcommittee and Regulatory Task Force meeting Thur., December 6 at 1:30 pm in Sacramento. Agenda attached, including link to join by webinar/phone.
  • CPDPC Operations Subcommittee meets Wed., December 12 at 9 am in Visalia. Agenda attached with link to join by webinar/phone.
  • The next meeting of the CPDPC Full Committee will be January 9 in Visalia. Agenda is pending. 
  • All meeting agendas and eventually the minutes are posted at https://www.cdfa.ca.gov/citruscommittee/ . All meetings are free and open to the public, and accessible via webinar.  

Additional Resources

 

And Now it's in Marin County

SACRAMENTO — Marin County has been placed under quarantine for the Asian citrus psyllid (ACP) following the detection of one ACP in the City of Novato. The entire county is included in the quarantine zone.

The ACP is an invasive species of concern because it can carry the disease huanglongbing (HLB), also known as citrus greening.  All citrus and closely related species, such as curry leaf trees, are susceptible hosts for both the insect and disease.  There is no cure once the tree becomes infected. A diseased tree will decline in health and produce bitter, misshaped fruit until it dies.  In California, HLB has been detected at residential properties in Los Angeles, Orange and Riverside counties. This plant disease does not affect human health.

Residents with backyard citrus trees in the quarantine area are asked not to transport or send citrus fruit or leaves, potted citrus trees, or curry leaves from the quarantine area. For commercial citrus, the quarantine prohibits the movement of citrus and curry leaf tree nursery stock, including all plant parts except fruit, out of the quarantine area. The quarantine also requires that all commercial citrus fruit be cleaned of leaves and stems prior to moving out of the quarantine area.  An exception may be made for nursery stock and budwood grown in USDA-approved structures that are designed to keep ACP and other insects out.

ACP quarantines are in place in Alameda, Contra Costa, Fresno, Kern, Kings, Madera, Merced, Monterey, Placer, San Benito, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, Solano, Stanislaus, Tulare, Yolo, Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura counties, as well as Marin.

Residents in the area who think they may have seen ACP or symptoms of HLB on their trees are urged to call CDFA's Pest Hotline at 1-800-491-1899 or a local agricultural commissioner's office  For more information on the ACP and HLB, please visit: www.cdfa.ca.gov/go/acp. Residents are also asked to follow these steps:

  • Inspect trees for the Asian citrus psyllid and Huanglongbing monthly, and whenever watering, spraying, pruning or tending trees. Psyllids are most noticeable when new leaves are growing on the tips of the branches.
  • As part of your tree care, visit your local nursery or garden center to get advice on products that can help protect your citrus tree.
  • Do not move citrus plants, foliage or fruit into or out of your area, and especially across state or international borders. This could unknowingly contribute to spread of the pest and disease.
  • When planting a new citrus tree, be sure to get your tree from a reputable, licensed nursery in your local area.
  • When grafting citrus trees, only use registered budwood that comes with source documentation, such as the budwood offered through the Citrus Clonal Protection Program.
  • Be sure to dry out citrus tree clippings or double bag them before removing the plant material from the property.

–California Department of Food and Agriculture

ACP adult and nymph
ACP adult and nymph

Posted on Friday, November 30, 2018 at 11:00 AM
Tags: acp (73), asian citrus psyllid (50), citrus (284), citrus greening (13), hlb (56), huanglongbing (57)

Great Citrus Tasting!!!!

Date: December 15, 2018

Time: 9:00 AM - 12:00 PM

Contact: Jasmin Del Toro: 559-592-2408 ext 1151

Sponsor: Lindcove Research and Extension Center

LocationLindcove Research and Extension Center

Event Details

The general public is invited to join us for a family friendly Citrus Tasting Event. You can see and taste more than 100 citrus varieties that are grown at Lindcove Research and Extension Center. Take a bag of fruit home for $10. Choose from Cara Caras, Navels, Mandarins, or assorted citrus from 4 bins located in front of the Conference Center. The Master Gardeners as well as UC Cooperative Extension Advisors will be happy to answer questions from home gardeners and citrus connoisseurs.

Directions: Take Highway198 east to Mehrten Drive (approximately 15 miles) and follow the signs to our Event. The University of Lindcove Research and Extension Center is located at 22963 Carson Avenue Exeter, CA. The Conference Center is located at the end of Carson Avenue. If you have any questions please contact Jasmin Del Toro at 559-592-2408 Ext 1151 or jzdeltoro@ucanr.edu

 Lindcove Fruit Display Tasting-home owners 2018

lindcove fruit tasting
lindcove fruit tasting

Posted on Friday, November 30, 2018 at 7:33 AM
Tags: citrus (284), fair (1), food (1), varieties (6)

Respirator Use from Ag Experts and CEUs

 

UC Ag Expert talks about respirators

Date: December 12, 2018

Time: 3:00 PM - 4:00 PM

Contact: Petr Kosina (pkosina@ucanr.edu)

Sponsor: UC Ag Experts Talk

Location: webinar

Event Details

Register in advance for webinar at

https://ucanr.edu/survey/survey.cfm?surveynumber=26029

Participants of this webinar will receive 1 hour of Laws & Regulations

Note: This webinar has a $10 registration fee. 

Lisa Blecker, Coordinator of the Pesticide Safety Education Program will cover the importance of respiratory protection, types of respirators used by pesticide handlers, how to determine when to wear a respirator, and federal and state requirements for respiratory protection. This information is critical for employers and supervisors to ensure compliance, and for applicators to understand how to protect themselves.

Event Reminder

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respirator picture
respirator picture

Posted on Thursday, November 29, 2018 at 3:53 PM
Tags: ag expertsl (1), respirator (1)

Not Just Navels Split

It has been a struggle to get through these hot times and now it's getting cooler, it's even rained, and suddenly that beautiful citrus that has just broken color and is an orange globe splits.  It's most common in navels, but all citrus that ripen in the fall – tight-skinned satsuma mandarins, early clementines, tangelos and blood oranges.  With the hot summer, it seems that a lot of citrus fruit have accelerated their maturity and are ready, ripe and sweet right now, and maybe ready to split.

And that's the problem. Drought stress.  Salt stress due to drought.  Water stress due to miserly watering. A heat wave in July.  And a weird fall with maybe rain and maybe no rain and is ¼ inch considered rain or just a dedusting? Irregular watering is the key to splitting this time of year.  The sugar builds, the pressure to suck in water builds and the fruit has been held back by a constrained water pattern and suddenly some water comes and it goes straight to the fruit and Boom, it splits.

Years of drought, and a stressed tree are a perfect set up for a citrus splitting in fall varieties like navel and satsuma.  The days have turned cooler and there's less sense on the part of the irrigator to give the tree water and suddenly out of nowhere, there is rain.  That wonderful stuff comes down and all seems right with the world, but then you notice that the mandarin fruit are splitting.  Rats? Nope, a dehydrated fruit that has taken on more water than its skin can take in and the fruit splits.  This is called an abiotic disorder or disease.  However, it's not really a disease, but a problem brought on by environmental conditions. Or poor watering practices.  

Fruit that is not yet ripe, like ‘Valencias' and later maturing mandarins are fine because they haven't developed the sugar content and have a firmer skin.  They then develop during the rainy season when soil moisture is more regular.  Or used to be more regular. With dry, warm winters this may become more or a problem in these later varieties, as well.

Several factors contribute to fruit splitting.  Studies indicate that changes in weather, including temperature, relative humidity and wind may exaggerate splitting.  The amount of water in the tree changes due to the weather condition, which causes the fruit to shrink.  Then with rewetting, the fruit swells and bursts.  In the navel orange, it usually occurs at the weakest spot, which is the navel.  In other fruit, like blood orange, it can occur as a side split, as seen in the photo below.

Proper irrigation and other cultural practices can help reduce fruit spitting.  Maintaining adequate but not excessive soil moisture is very important.  A large area of soil around a tree should be watered since roots normally grow somewhat beyond the edge of the canopy.  Wet the soil to a depth of at least 2 feet, then allow it to become somewhat dry in the top few inches before irrigating again.  Applying a layer of coarse organic mulch under the canopy beginning at least a foot from the trunk can help moderate soil moisture and soil temperature variation.

Once split, the fruit is not going to recover.  It's best to get it off the tree so that it doesn't rot and encourage rodents.

blood orange split
blood orange split

Posted on Tuesday, November 27, 2018 at 7:25 AM
Tags: abiotic disorder (1), citrus (284), mandarin (64), navel (11), orange (66), split (2)

Fruit Tree Training by the Best

So an avocado is not an almond.  But it they are both trees that are manipulated for production.  And many of the principles can be transferred.  Some can't.  But this is a great opportunity to learn some basic ideas about how to grow tree crops.  And enjoy the great Valley winter weather!!!!!!

“Registration for the 2018 UC Davis Extension Course: Principles of Fruit and Nut Tree Growth, Cropping and Management is now open.

The University of California Cooperative Extension (UCCE) and University of California, Davis (UCD) Plant Sciences department are offering the annual two-week course from February 25th through March 7st, 2019 at UC Davis, CA.

Understanding the fundamentals of tree biology is essential to making sound orchard management and business decisions in the tree fruit and nut industry. However, access to educational courses on basic fruit and nut tree biology, and how it relates to horticultural practices, is limited. This course incorporates lecture, lab exercises, and field demonstrations to provide information on all aspects of basic plant biology and the relationship between plant biology and orchard management.

During the first week of the course (February 25 - March 1), leaders in tree crop research from the University of California will provide lectures on tree growth, development and pruning, dormancy and chilling, flowering, pollination and fruit set as well as many other topics critical to a solid understanding of fruit and nut orchard management. There will also be field excursions for hands-on field exercises and demonstrations.

The optional second week (March 4 – March 7) is a four day field tour throughout tree fruit and nut growing regions in Northern and Central California. The field tour includes visits to current UC experiments, processing facilities, and orchards in a wide range of tree fruit and nut crops.

This course is designed specifically for current tree fruit and nut growers and professionals and also for those with small acreage farms or new to the fruit and nut business.  Attendees will receive a certificate after completing the course.

The fee is $2,850 for the entire course (plus the lodging cost for the field trips), or $1,850 for the first week only.

Please visit http://fruitandnuteducation.ucdavis.edu/education/principles/ for more information on the program and our instructors, and to register. Please contact the Fruit and Nut Research Center at fruitsandnuts@ucdavis.edu or 530-752-4279 or if you have any questions.”

 

Fruit and Nut Research and Information Center

Department of Plant Sciences

One Shields Avenue

Davis, CA  95616  USA

Office: 530 752 4279

E-mail: fruitsandnuts@ucdavis.edu
Web: http://fruitsandnuts.ucdavis.edu

Twitter: @FruitandNut_UCD

Facebook: https://www.facebook.com/ucfnric/

fruit tree class Page 1
fruit tree class Page 1

Posted on Monday, November 26, 2018 at 10:31 AM

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