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

Posts Tagged: avocado

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)

Why O Why, One Tree???

It's winter time and avocados and other subtropicals are prone to frost damage.  Little trees especially that haven't developed a canopy that can trap heat are the most prone.  So it gets cold and all the orchard looks fine, but there's one tree that doesn't look right and in a couple of days it really stands out.

Here's an example of a year old tree that turned brown and it actually looks like it was doing better than the trees surrounding.  It's bigger and has a fuller canopy..... or at least it did. 

But there's all the symptoms of frost damage - bronzed leaves and dead tips.

A week after the cold weather, there is already sunburn damage on the exposed stems.  See the brown spots on the upper fork?  That will soon turn all brown and dry up.

This is still a healthy tree with green stems, in spite of the burned leaves. Now is the time to protect the tree from sunburn damage.  This is what can kill the little tree.  Time to white wash it.

Why did it happen to this one tree?  Maybe it was a little bigger and needed more water than the surrounding trees. Maybe sitting on a rock and didn't have enough rooting volume for water. Maybe a touch of root rot (although the roots looked pretty good even for winter time).  And there were ground squirrels in the area.  Easy to bklamne them.


Listen to the sound of winter frost control


And when freeze damage gets extreme




Posted on Wednesday, January 23, 2019 at 6:22 AM
Tags: abiotic (13), avocado (266), citrus (295), damage (23), freeze (9), frost (17), subtropical (2), winter (6)

Mulch and Avocado Root Rot and Gibberellic Acid Too!

Upcoming CAS/UC/CAC Seminar Addresses


             Phytophthora and

                     Gibberellic Acid Use

  • Jan 07, 2019

The California Avocado Society will host the first of its 2019 California Avocado Growers Seminar Series with workshops focused on mulch and Phytophthora. Dr. Ben Faber, Dr. Tim Spann and Dr. Carol Lovatt will deliver presentations at the seminars.

Dr. Ben Faber, UC Cooperative Extension Soils/Water/Subtropical Crops Farm Advisor, will speak about the benefits of using mulch in avocado groves. Ben will discuss the various types of mulch that can be used, how and when to apply them and the benefits of using mulch in avocado groves.

Dr. Tim Spann, California Avocado Commission Research Program Director, will cover Phytophthora 101. Tim will discuss what phytophthora species affect avocados, how to recognize symptoms of phytophthora infection in avocados and best management practices for dealing with phytophthora.

Dr. Carol Lovatt, UC Riverside Emeritus Professor of Plant Physiology, will discuss the use of gibberellic acid (GA) plant growth regulator on avocados. A special local needs registration was obtained in early 2018 for use of GA on avocado in California. Carol will discuss the benefits of using GA, and when and how to apply it for those growers interested in trying this new tool.   

The seminars will be held as follows:

Tuesday, February 5, 1:00 p.m. – 3:00 p.m.
SLO Farm Bureau, 4875 Morabito Place, San Luis Obispo, CA 93401

Wednesday, February 6, 9:00 a.m. – 11:00 a.m.
UC Cooperative Extension Office Auditorium, 669 County Square Drive, Ventura, CA 93003

Thursday, February 7, 12: 30 p.m. – 2:30 p.m.
Fallbrook Public Utility District Board Room, 990 East Mission Road, Fallbrook, CA 92028


And read more about Mulch Myths:



euc and a bit of scrap
euc and a bit of scrap

Posted on Friday, January 18, 2019 at 7:52 AM
Tags: avocado (266), flowering (4), fruit set (4), gib acid (1), mulch (12), root rot (19)

Better Soil, Better Water Workshop

SWEEP and Healthy Soils Grants

Opportunity Workshop

February 14, 2018

Ventura, CA

Co-sponsored by

University of California Cooperative Extension

Ventura County Farm Bureau

Ventura Co. Resource Conservation District

CA Dept of Food & Agriculture


Why:             Apply for CDFA funding- State Water efficiency and Enhancement Program (SWEEP) and Healthy Soils Program (HSP).Receive up to $100,000 in grant funding to improve your on-farm water and energy efficiency and healthy soil practices through the grant funding programs. During the workshop irrigation specialists will:

  • Provide a comprehensive review of SWEEP/HSP and summary of other CDFA Climate Smart Grant programs
  • Guide you through the required water savings and greenhouse gas reduction calculations
  • Show you how to assemble a strong grant proposal


When:          Thursday, February 14, 2019

                        2:00 PM - 4:00 PM

Where:         UC Cooperative Extension office, 669 County Square Dr., Ventura 93003. California Conference room

Presenters:     Andre Biscaro, Irrigation and Water Resources Advisor

                        Jamie Whiteford, Irrigation Specialist, Ventura/Cachuma RCDs

Khaled Bali, Irrigation Specialist, UC Kearney Agricultural Research and Extension Center

Daniele Zaccaria, Agricultural Water Management Specialist, UC Davis

Registration:  To register go to:

Questions:      Contact Andre Biscaro, 805-645-1465, email:

Grant info.:    Applications are due March 8, 2019 online at


The SWEEP/HSP provides financial assistance in the form of grants to implement irrigation systems that reduce greenhouse gases and save water on California agricultural operations. Eligible system components include (among others) soil moisture monitoring, drip systems, switching to low pressure irrigation systems, pump retrofits, variable frequency drives and installation of renewable energy to reduce on-farm water use and energy.

Please feel free to contact us if you need special accommodations.


Free One-On-One Technical Assistance to Apply for Grant Funds

Need help in developing and /or submitting your project proposal? Schedule your free one-on-one Technical Assistance session, contact your local UC Cooperative Extension Office for additional information at 805-645-1465

The University of California prohibits discrimination or harassment of any person in any of its programs or activities. (Complete nondiscrimination policy statement can be found at Inquiries regarding the University's equal employment opportunity policies may be directed to Affirmative Action Contact and Title IX Officer, University of California, Agriculture and Natural Resources, 2801 2nd Street, Davis, CA 95618, (530) 750-1397;


Posted on Thursday, January 17, 2019 at 6:01 AM
Tags: avocado (266), citrus (295), HSP (2), SWEEP (3), workshops (1)

Yikes!!! More Shot Hole Borers

So Many Shot Hole Borers: New Research Charts Four Nearly Identical Species

by Jiri Hulcr, Ph.D., and Jackson Landers

When an insect spends most of its life in total darkness, it doesn't much matter what color it is. So, it comes as no surprise that so many species of bark and ambrosia beetles maintain the same brown hue as they slowly tunnel through wood and feed on a fungus that they carry with them into their trees. This similarity of appearance has been taken to an extreme in what has turned out to be a cryptic species complex. What was once referred to as the “tea shot hole borer” is actually four distinct species who all look almost exactly the same.

The tea shot hole borer first attracted notice from North American entomologists when it appeared in Florida in 2012, appearing harmless. But the beetles were first described as an economically significant pest in Sri Lanka in 1968. In 2009, the beetles were found eating through avocado and street trees in Israel. Then, in 2012 in California, with a bang, avocado trees were being attacked and killed. Given the value of global avocado crops and tea plants, entomologists had to start taking a closer look at these beetles.

Many taxonomists eventually came around to the idea that they were looking at three identical species rather than one: the tea shot hole borer (from southern Southeast Asia), the Kuroshio shot hole borer (originating in the Pacific Islands), and the polyphagous shot hole borer (presumed native to northern Southeast Asia). A 2017 paper authored by Richard Stouthamer and his team from the University of California, Riverside, first designated those three clades and established common names for them.


The four newly delineated species of the Euwallacea fornicatus species complex are, from left to right, E. fornicatior, E. fornicatus, E. whitfordiodendrus, and E. kuroshio. The wood-boring beetles known as various kinds of “shot hole borers” are so similar in morphological characteristics while also variable in body dimensions that their appearance can't be reliably used for differentiating specimens. (The four shown here vary in size but some of their cousins within each species can all range from 1.8 to 2.9 millimeters long.) New research has used molecular genetic techniques to identify the different species within the complex. (Photo credit: Demian Gomez)


And read more from the folks at UC:



Posted on Monday, January 14, 2019 at 6:39 AM
Tags: avocado (266), laurel wilt (6), shot hole borer (8)

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