February 15 (10 AM - 12 PM)

In-Person and Zoom

Get Down - Fertilizers

 
in-person meeting will be at:

United Water Conservation District offices (1701 N. Lombard ST., Oxnard)

and zoomed for those who would prefer that option.

In 2004, Avocado Lace Bug was identified in backyard trees in Chula Vista and National City in San Diego County, probably originating from Mexico. Later in 2017, ALB was being picked up in the Oceanside, Fallbrook, and Temecula areas apparently originating from more Caribbean/Florida sources. That year, it also showed up in Long Beach and Culver City, and of the Mexican origin like in Chula Vista. Then in 2021, it showed up in Carpinteria, previously causing some major issues in Oahu, Hawaii that same year.

There has been some infill in the California infestations along the way, but it has not appeared to be as aggressive a spreader as persea mite or avocado thrips. Recently it was identified at a new site in Orange County. Mark Hoddle's lab at UC Riverside is following the spread and has helped in identifying where the infestations have been originating through DNA analysis.

Identification of ALB is quite easy since there are no other pests in California that it can be easily confused with. The first thing that usually draws your attention when looking for ALB is “islands” on the leaves. These necrotic regions develop because of the ALB adults feeding on the underside of the leaves and sucking the leaf juices from between the upper and lower leaf surfaces.

When the leaf is turned over, the adults, although only about 2 mm in length, are easily seen with the naked eye. Adults are oval, appear yellow to pale orange, and have dark heads. Nymphs are smaller than adults, oblong and are black, dark brown or reddish colored depending on their stage of development. Eggs appear as small black dots of varying sizes. What is visible is a dark sticky secretion covering the egg to protect it from predation. Under the sticky secretion, the eggs are oblong and yellowish.

Keep your eyes open for the damage and the pest, they are quite distinctive. The earlier it can be treated, the better the eventual control.

What Can Happen With Too Much Rain?  And Mud?

Rain is wonderful stuff. If it comes and washes the accumulated salts of the last several years out of the root zones of citrus and avocado, that's a good thing. But what happens if there is a little too much of the good stuff? In the winter of 2005, Venture got over 40” of rain, which is 200% of what is normal. The last time big rains occurred prior to that was in the winter of 1997-98. That year the rains were evenly spaced on almost a weekly basis through the winter and into the late spring and over 50" fell. That year we had major problems with both citrus and avocados collapsing from asphyxiation. The same occurred in 2005, but not so pronounced.

This winter we have had a lot more rain than we normally see and in some young trees with poorly developed root systems, we have seen some collapse.from asphyxiation. Avocados tend to be more susceptible than citrus, and some rootstocks more than others. We have also had some trees buried in mud slides, which can also lead to asphyxiation.

Asphyxiation is a physiological problem that may affect certain branches, whole limbs or the entire tree. Leaves wilt and may fall, the fruit withers and drops and the branches die back to a greater or lesser extent. The condition develops so rapidly that it may be regarded as a form of collapse. Usually, the larger stems and branches remain alive, and after a time, vigorous new growth is put out so that the tree tends to recover. Young trees can be harder hit, but sunburn damage from lack of leaves may be more of a problem.

Asphyxiation is related to the air and water conditions of the soil. The trouble appears mainly in fine-textured or shallow soils with impervious sub-soils. In 1997-98, this even occurred on slopes with normally good drainage because the rains were so frequent. When such soils are over-irrigated or wetted by rains, the water displaces the soil oxygen. The smaller roots die when deprived of oxygen. When the stress of water shortage develops, the impaired roots are unable to supply water to the leaves rapidly enough and the tree collapses. The condition is accentuated when rainy weather is followed by winds or warm conditions. These are exactly the conditions we have seen in the last two weeks, hence some of the problems in young orchards on heavier soils.

It doesn't take standing water to have asphyxiation occur.

Canopy treatment in less severe instances of asphyxiation consists of cutting back the dead branches to live wood. If leaf drop has been excessive, the tree should be whitewashed to prevent sunburn. Fruit, if mature should be harvested as soon as possible to prevent loss. In the case of young trees, less than two years of age, recovery sometimes does not occur, and replanting should be considered if vigorous regrowth does not occur by July. As soon as defoliation is evident, whitewashing should be done to protect them to give them a chance for recovery.

Asphyxiation can be reduced by proper planting and grading. If an impervious layer is identified, it should be ripped prior to planting. The field should be graded so that water has somewhere to run off the field during high rainfall years. Heavier soils might require planting on berms or mounds so that the crown roots have a better chance of being aerated.

Hindsight is always great. Post-plant, if an impervious layer can be identified and is shallow enough to break through, ripping alongside the tree or drilling 4-6 inch post holes at the corners of the tree canopy can improve drainage. It is important that the ripper blade or auger gets below the impervious layer for this technique to be effective. If there is a thick layer of mulch reducing soil evaporation, pulling it back to allow the sun to help dry it out faster will help. It's not a lot of work with small trees, but big time work if it's big trees with thick mulch.

Asphyxiated tree that has been whitewashed

In the case of trees being buried, especially covering the bud union, they should be dug out as soon as practical.They need to be dug out down to the original ground level about 3 feet out from trunk.  Then over time, excavated out about 6-8 feet from trunk.  It doesn't have to be done today, but soon, before the weather heats up and transpiration demand increases.  So in the next month at latest.  Start slow and gradually the mud can be moved out further from the tree.

Trees buried above bud union that need to have soil removed down to original soil level.

Planning and Planting the Small Orchard Block

February 23-26, 2023

Course Overview

This new short course will offer a wealth of information from orchard expert, Orin Martin, long-time manager of the Alan Chadwick Garden and instructor at the UC Santa Cruz Center for Agroecology. The course will walk participants through the planning and planting of a new apple orchard block at the UCSC Farm, from site selection and soil preparation to sourcing and planting quality trees (in quality holes). At the UCSC Farm and Alan Chadwick Garden, participants will look at orchard blocks of different ages and varieties for lessons on seasonal care, pest/disease/weed management, and winter pruning. At Fifth Crow Farm, participants will visit an orchard block Martin helped plant with the Fifth Crow farmers 15 years ago and hear from the farmers about the orchard's growth, maintenance, and production for their diversified organic farm with direct markets around the Bay Area. The course includes an introductory webinar online along with a set of videos on soil preparation for the orchard block, planting, winter pruning, summer pruning, and more.

The course will have an emphasis on growing apples, but will also cover pears and stone fruit. Key considerations, concepts, and skills covered will include:

• Site selection - flat ground or sloping ground, aspect (direction of slope)
• Sunlight (>6-8 hr/day)
• Climate and weather (microclimate too)
• Soil (assessment and improvement)
• Fertility plan
• Scale and types of fruit to be grown
• Orchard layout
• Rootstock selection (size control)
• Sourcing quality trees
• Pollination factors
• Irrigation
• Weed management
• Pruning and training
• Pests/disease
• Planting and seasonal care

This is a course for anyone, novice to intermediate-level grower, wanting to learn more about the 'hows (skills and techniques) and whys (a little of the relevant science behind the hows (in bite-sized, digestible morsels)' of deciduous fruit tree growing.

About the Instructor

Orin Martin is the author of Fruit Trees for Every Garden: An Organic Approach to Growing Apples, Peaches, Plums, Citrus and More (2020 American Horticultural Society Book Award Winner). Since 1977, he has taught classes, lectures, and workshops to thousands of home gardeners, apprentices, students, and budding farmers.

About Fifth Crow Farm

Fifth Crow Farm, a diversified organic farm founded in 2008, is located in Pescadero about 35 miles north of Santa Cruz. The three farmer/owners—Teresa Kurtak, Michael Irving, and John Vars—and a committed team of farm staff manage 30 acres of row crops, a 24-variety apple orchard, a young pear orchard, and a pastured egg operation, marketing through a CSA and farmers markets throughout the Bay Area, as well as to restaurants. For information about their farm and orchard operation, visit their website.

Registration Information

Pre-registration for the course is required. The course carries extension credit from UCSC Extension and has a $200 fee. REGISTER FOR THIS COURSE

Scholarship Information

Scholarships are available. APPLY NOW FOR A SCHOLARSHIP

Course Schedule

• Thursday, February 23rd, 5:30-7:00pm — Online introductory webinar
• Saturday, February 25th, 9:00am -12:00 pm — UCSC Farm; 1:00-4:00pm — Alan Chadwick Garden
• Sunday, February 26th, 9:00 am-12pm —Fifth Crow Farm

See Also

• Organic Citrus Growing Short Course
• Short Courses