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

Posts Tagged: citrus

Learning How to Spray Trees Better

Dr. Peter Ako Larbi is a Cooperative Extension Specialist in agricultural engineering with UC ANR. As part of his research and extension program, his focus is on developing and promoting best practices for safe, economical, and environmentally sound pesticide application with reduced environmental risks. He is based at the Kearney Agricultural Research and Extension Center in Parlier. 

Prior to joining ANR, Dr. Larbi had been an Assistant Professor of Agricultural Systems Technology in the College of Agriculture at Arkansas State University since 2014. He developed an integrated teaching and research program related to agricultural systems technology; developed and managed research in precision agriculture, agricultural machinery systems, remote sensing and sensor technology; and provided service to the university, college, local community and general scientific community. He held a joint appointment in the Division of Agriculture at University of Arkansas.

From 2012 to 2014, Dr. Larbi was a postdoctoral research associate at the Center for Precision and Automated Agricultural Systems at Washington State University. From 2011 to 2012, he was a postdoctoral researcher at the University of Florida Citrus Research and Education Center.

Larbi earned a Ph.D. in agricultural and biological engineering from University of Florida and a M.Sc. and a B.Sc. in agricultural engineering from Kwame Nkrumah University of Science and Technology in Kumasi, Ghana.

Dr. Larbi invites you to kindly take the following needs assessment survey to help him assess outreach, education, and training needs in pesticide spray application to better plan and implement a program that serves the people of California well:

Please contact him at if you need further information. Thank you very much for your assistance.

citrus spray blast
citrus spray blast

Posted on Friday, February 15, 2019 at 7:04 AM
Tags: citrus (295), pesticides (23), spray (6)

Nemas and What YOU Need to Know

Plant-parasitic nematodes are microscopic, unsegmented roundworms that live in soil and plant tissues and feed on plant roots. The predominant species parasitic on citrus in California is the citrus nematode. This nematode is reported to be present in most citrus orchards and in all soil types. It also parasitizes grape, lilac, olive, and persimmon. Citrus nematode attacks roots by burrowing its anterior end deep inside the root cortex while the posterior end remains outside in the soil.

The sheath nematode is less widespread than the citrus nematode; it has been found on citrus in the Coachella Valley and on some native desert plants. However, it has a broad host range and thrives well at high temperatures and at low moisture levels

 From UC IPM Pest Management Guideline:

Citrus nematodes, Tylenchulus semipenetrans, parasitizing a citrus root. The second-stage larvae initially feed on root hairs. The larvae then penetrate into the feeder roots, molt three times, and establish a permanent feeding site (nurse cells) inside the root cortex. The swollen rear end of the mature female remains outside the root

Find out more about these underground animals from UC AG Expert, Ole Becker.


Management of plant-parasitic nematodes in citrus orchards - Thursday, February 21, 2019, from 3-4 pm

Dr. Ole Becker, cooperative extension specialist & nematologist at UC Riverside, will discuss plant-parasitic nematodes in citrus, their biology, symptoms, and management, including soil & root sampling, interpretation of analysis results, and rootstock selection. One DPR CE hour (other) and one CCA CE hour (IPM) were approved.


And there's more to hear, coming up:

Laurel wilt - Wednesday, March 20, 2019, from 3-4 pm

Dr. Monique J. Rivera will present current knowledge of the laurel wilt, its biology, and spreading. More information to come.

Management of Glyphosate-Resistant Weeds in Orchard Crops - Wednesday, April 24, 2019, from 3-4pm

Dr. Brad Hanson, cooperative extension specialist, will discuss what is herbicide resistance, current state of resistant weeds in CA permanent crops, identification and lifecycle of key glyphosate-resistant weeds, selection pressure for resistant biotypes and species, herbicide modes of action, and examples of herbicide programs for orchard crops. One DPR CE hour (other) and one CCA CE hour (IPM) are pending.

To register for any of the above webinars, please visit and click on the relevant link on the top of the page.

Recordings of the past webinars are available on UC IPM YouTube channel at

CE hours are NOT available for recorded webinars.


Please note that webinars are targeted to growers and pest control professionals (PCA, QAL, CCA). Master Gardeners may benefit from participation, however, presented pest management methods, especially chemical control, may not be relevant for them.



Check those roots to see if they are healthy


citrus nema damage
citrus nema damage

Posted on Wednesday, February 6, 2019 at 7:59 AM
Tags: citrus (295), nematode (1), tylenchulus (1)

Visit UC ANR at the World Ag Expo, Feb. 12-14

Attractions in the UC ANR tent at space 137 on I Street, just west of Pavilion A, include the opportunity to meet researchers, enjoy fresh citrus from the Lindcove Research and Extension Center, taste moringa tea, and enter to win a poster-size satellite image of one's own farm.

TULARE, Calif. — The public is invited to taste, see and learn about many UC Agriculture and Natural Resources programs offered in California at the World Ag Expo, the world's largest agricultural exposition to be held in Tulare Feb. 12-14. The Expo is at the International Agri-Center, 4500 S. Laspina St., Tulare.

Attractions in the UC ANR tent at space 137 on I Street, just west of Pavilion A, include the opportunity to meet researchers, enjoy fresh citrus from the Lindcove Research and Extension Center, taste moringa tea, and enter to win a poster-size satellite image of one's own farm.

The tent displays include leaf-footed bugs controlled by microbes, traps for managing vertebrate pests, the superior quality of soils managed with conservation techniques, and high-tech ag innovations, including a drone.

In two booths inside Pavilion A (1411 and 1412), the UC ANR programs that target the general public will be featured. The Tulare County nutrition educators will be playing nutrition Jeopardy! with visitors. The UC Master Gardeners will reach out with research-based gardening information. The 4-H Youth Development program will invite all youth to peer into virtual reality goggles to give them an idea about the fun activities that can be part of joining 4-H.

With VR goggles, viewers can be immersed in expeditions from Mount Everest to the undersea world. Expeditions explore history, science, the arts and nature. World Ag Expo visitors will have the opportunity to experience a variety of virtual experiences, from scuba diving with sea lions to flying over Greece.

Two UC ANR academics are presenting seminars during the the show.

Getting it Right: Livestock's Environmental Story
1 to 2 p.m., Feb. 12, in seminar trailer 1
Frank Mitloehner, UC Cooperative Extension specialist
Mitloehner will discuss confusion in the media about the impact livestock supposedly has on our environment. This presentation reviews how the efficiencies in livestock production and environmental emissions are related, and how our producers are leading the way to a “greener future” for California and U.S. agriculture.

Asian Citrus Psyllid and Huanglongbing – Regulatory Compliance Update and Treatment Protocols
12 to 1 p.m., Feb. 13, in seminar trailer 1
Beth Grafton-Cardwell, UC Cooperative Extension citrus entomology specialist
Victoria Hornbaker, California Department of Food and Agriculture
An update on regulatory protocols relating to Asian citrus psyllid and HLB quarantines and the proper transportation of bulk citrus to mitigate against the spread of the pest and disease. Speakers will review the University of California recommended treatment options for Asian citrus psyllid in commercial citrus groves and residential citrus trees. Continuing Education units have been requested.

UC VINE will hold a meeting with Dutch agtech professionals during World Ag Expo

The California and Dutch AgFoodTech innovation partnership is reuniting in California during the show to share their action plan and scope the projects. Contact Gabe Youtsey, UC ANR chief innovation officer, to request an invitation to the presentation and networking luncheon on Feb. 12 at the UC Cooperative Extension office across the street from the International Agri-Center in Tulare.

–UC Agriculture and Natural Resources


citrus cornucopia
citrus cornucopia

Posted on Monday, February 4, 2019 at 6:56 AM
Tags: AG Fair (1), ANR (1), citrus (295), exposition (1), Tulare (1)

Tree Staking Myths

"Trees should be firmly staked at planting"

        MYTH!!!!!!!!!!!!!!! Read on:

Chalker-Scott, L. , Extension Specialist And Associate Professor, Washington State University
Downer, A.J., Farm Advisor, University of California

Nursery-grown shade trees are often rigidly staked to prevent blowdown and damage during cultivation. In some cases, trees are pruned to a long, untapered standard with a bushy top that requires a tight stake to hold it up. Nurseries often remove side branches from the young trunk and while this creates the illusion of a small tree, the practice actually inhibits the development of taper in the trunk (Harris, 1984; Neel and Harris, 1971). Trees without taper will not stand without staking. Poor culture of ornamental trees in nurseries necessitates staking once trees are planted into landscapes because they do not have the structural development in their trunks to stand on their own. Due to these cultivation errors, landscape installers frequently keep the nursery stake and add more stakes to firmly secure the tree in place and further prevent its movement in the landscape.

Staking takes three basic forms: rigid staking, guying, and anchoring. All methods of staking reduce development of taper, increase height growth, and decrease caliper of the developing tree relative to unstaked trees (Figure 7). Moreover, improper staking can result in increased tree breakage either during the staking period or after staking is removed (Figure 8a-b) (Thacker et al., 2018).

Decades ago, researchers discovered that movement of the trunk and branches is necessary for the development of trunk taper (Neel and Harris, 1971). Trees grown in a growth chamber without movement did not develop taper and instead grew taller, while trees in an identical chamber that were hand shaken each day developed significant taper and remained shorter.

Until trees are established in landscapes they may require some staking. In areas of high wind, guying (which involves cables staked to the ground) gives the greatest protection against main stem breakage or blowover (Alvey et al., 2009). Whatever system is used, any such hardware should be removed as soon as the tree can stand on its own:

  • The traditional two stakes and ties system is the least harmful to trees staked in landscapes.
  • Staking should be low and loose to allow trunk taper to develop naturally.
  • Remove all staking material as soon as possible.

If a tree is not established after a year of staking, it is unlikely to ever establish

Read on:

avocado lindcove
avocado lindcove

Posted on Friday, February 1, 2019 at 6:07 AM
Tags: avocado (266), citrus (295), planting (8), stake (1)

ACP and HLB News

News from the Ventura County ACP-HLB Task Force

Winter 2019 area-wide treatment cycle has begun

This is a reminder that the Winter 2019 area-wide management (AWM) treatment window opened Jan.7. You are encouraged to file pesticide use reports (PURs) electronically through CalAgPermits, Agrian, or another system that allows treatments reports to be rapidly filed and recognized. Treatment reminders will be emailed (mailed for those without an email record) about 2-3 weeks prior to the treatment window. In some instances, our contact list may only have contact information for your farm manager, pest control advisor, or pest control operators. If you are not receiving emails, please contact one of your grower liaisons (see contact information below) to receive information about ACP, HLB and your citrus.

Website redesigned

The Citrus Pest & Disease Program (CPDPP) launched a redesign of its website to provide members of California's citrus industry easier access to the key maps, regulatory updates and events they need to stay informed on the fight against HLB in California. The website is at

HLB confirmations continue to increase

At least 1,024 residential trees had been confirmed as infected with HLB as of January 2019. No HLB-positive trees have been found in commercial groves. The HLB quarantine boundaries and the latest tally of HLB confirmations, updated weekly, is available online at

Report neglected and abandoned citrus

Help prevent neglected and abandoned citrus from serving as a breeding ground for ACP and the spread of HLB by reporting its location County Agricultural Commissioner's office at (805) 388-4222. If your citrus is not worth the resources required to protect it from ACP and HLB, it may be a good time to consider removing the trees. Tree-removal assistance is offered to small growers through the California Citrus Mutual and Bayer's ACT NOW program. For more information contact Joel Reyes at or (559) 592-3790.



UCR Citrus Day (Jan. 29)

This year's UC Riverside Citrus Day will be on Tuesday, Jan. 29. Agenda and registration information can be found by clicking here.

International Research Conference on HLB/Citrus Virologist Conference (March 10-15)

The joint International HLB and Citrus Virologist conference will be at the Riverside Convention Center in Riverside, CA. Registration and more information can be found here.

Citrus Pest and Disease Prevention Committee meeting (March 12)

The CPDPC is charged with advising the state on management of the Citrus Pest and Disease Prevention Program. The CPDPC and subcommittee meetings are open to the public, and options for participation include in person or by webinar and conference call. Click here to view and register for upcoming committee and subcommittee meetings. Attendance is free. 



University of California ACP area-wide materials list and ACP monitoring protocols

Movement of bulk citrus materials list

Ventura County AWM maps and schedule

Citrus Pest and Disease Prevention Program

Ventura County ACP-HLB Task Force mailing list signup


Contact your grower liaisons if you have additional questions: 


Sandra Zwaal

(949) 636-7089


Cressida Silvers

(805) 284-3310

hlb defprmed citrus
hlb defprmed citrus

Posted on Friday, January 25, 2019 at 6:29 AM
Tags: acp (75), asian citrus psyllid (51), citrus (295), hlb (58), huanglongbing (58), lemon (91)

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