- Author: Jim Downing , UC Agriculture and Natural Resources Lucien Crowder, UC Agriculture and Natural Resou
California avocados often are exposed to high temperatures after harvest, either in the field or during preconditioning (ethylene treatment), especially in summer. It's been known that long periods of high temperatures can delay ripening time and reduce fruit quality, but a new study indicates pronounced effects after only short periods of high temperature following harvest. Authors of the study concluded that it's important to maintain avocados at temperatures below 25°C following harvest and that the ideal temperature to ripen the fruit is 20°C. The authors also found that ripening below 20°C resulted in significantly longer ripening times and resulted in poorer coloration of the ripened fruit.
Mary Lu Arpaia, UC Cooperative Extension specialist, Jim Sievert and Sue Collin, staff research associates (retired) in the Department of Botany and Plant Sciences at UC Riverside, working with David Obenland, research physiologist with the USDA Agricultural Research Service, Parlier, studied for two seasons holding avocados from multiple harvest times for the first 24 or 48 hours of the ripening period at high temperatures (20°C to 35°C), with and without ethylene. In the third season, they made a detailed assessment of ripening temperatures (15°C to 25°C) on ripening time and fruit quality.
Results from the first two seasons showed that even a 24-hour exposure to temperatures of 25°C and above inhibits ripening and increases postharvest disorders such as stem end rot and body rot. In season 1, the incidence of stem end rot increased from 9.7% at 20°C to 32.3% at 35°C, and body rot increased from 3.9% to 20.2% for the same treatment comparison. Ethylene applied during the exposure period was ineffective in preventing the disorders.
In the third-season trial, temperature was also shown to be critical. Fruit ripened below 20°C took slightly longer to ripen. Additionally, the authors found that the ripened fruit at either 15°C or 18°C remained more green then fruit ripened at the higher temperatures. Avocados ripened above 20°C were more likely to develop pink discoloration in the mesocarp. Ripening temperature had no effect on overall likeability, or ratings of grassy or rich flavor.
- Author: Ben Faber
Got trees/brush to remove?
The CREW is ready to work:
With a decline in federal funding to work on Forest Service lands and elsewhere our local non-profit, The CREW is looking for work. They are great at getting all kinds of brush cleared, trees removed and as a non-profit their rates are reasonable. In hiring The CREW you are helping train a new generation of folks to use saws and work in the field.
If you have need for dead trees/limbs to be removed, one local resource is The C.R.E.W. - Concerned Resource & Environmental Workers. Since 1991 this Ojai-based nonprofit has provided paid employment to young people in conservation and forestry work. With a workforce trained in chainsaw use for fire abatement, The C.R.E.W. is available at a reasonable fee to take down trees and limbs in orchards. They also have a chipper.
The C.R.E.W. works throughout Ventura and Southern Santa Barbara counties. In fact, The C.R.E.W. was hired in 2016 by California Citrus Mutual to take out neglected orange trees on private property to limit growers' exposure to ACP/HLB.
If you're interested in learning more, contact Todd Homer at thomer@thecrew.org or call 805-649-8847.
CREW Equipment Ready
The CREW does great fire clearance.
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- Author: Ben Faber
One avocado tree, wholesale, recently sold for $92 in South Africa with 250 trees in a bunch costing about $23,000. They are ‘Maluma', of course, which means it is a new variety that has similar properties to the traditional ‘Hass', and might have some unusual properties like higher productivity, upright growth lending itself to higher planting density and fruit production inside the canopy protecting it from wind and sunburn (Fresh Fruit Portal, 2017).
At a traditional California tree spacing of 273 trees/ha, that would be $25,116 / ha. At some of the new high density spacings of 1 m x 1m, that is nearly a million dollars per hectare alone in trees, let alone the cost of the land and infrastructure. And that is just one hectare, not the multiples of hectares that growers are planting. There are growers investing in five, ten, twenty and more hectares per planting. Big investment.
One million dollars in trees. Nurseries are happy to hear this. If a grower in California or South Africa or Australia wants to plant a new orchard, they are told to get in line. And then, they need to wait for one or two years until the nursery can ramp up supply. I have gotten calls from China, Philippines, and Italy of all places for trees. Everyone wants to plant trees now, and this has been after a steady increase in world-wide planting that has gone on for the last 20 years. World-wide consumption has seen a steady increase over this time. World-wide, global marketing has assured a steady supply to local markets, regional markets and now all those consumers in far off places like North Dakota in the US, or other countries, such as Beijing and Moscow. French and German consumers have always been reliable importers of the fruit over the years. But now even traditional Italian foodies are eating the fruit.
What is driving this activity? Well, consumers, of course. They have caught the ‘avocado toast' bug. And the health benefits bug. It's all online and a lot of the claims are backed up by science (Scott et al, 2017). According to IndexBox (2017), a data compiling news service, the avocado market expanded at +5.6% per year from 2007 to 2016. Over the last six years, the market displayed a consistent growth; it accelerated sharply from Price of the fruit showed growth. Wholesale prices in 2016 totaled $13,797M, a growth by 23% over the previous year.
Read more at:
http://ceventura.ucanr.edu/news/Topics_in_Subtropics/
- Author: Ben Faber
Avocado is a neotropic tree which has been commercialized world-wide, yet it's native pollinators have been little studied. The most frequently studied pollinator has been the old-world insect, Apis mellifera. In commercial orchards it is common practice to introduce honey bee colonies, although it is not clear exactly what the extent of their effect is in California orchards in the presents of native bees and other pollinators. The purpose of this study is to evaluate the range of avocado flower visitors and to assess whether those numbers can be affected by the introduction of gardens that might promote their numbers in the orchards during the avocado bloom period.
Measuring pollinator performance is difficult because of weather impacts, alternate bearing habit and the high level of fruit shedding in avocado. In this study, pollination gardens have been established in three avocado orchards in coastal California near Santa Barbara, just north of Los Angeles. These gardens have been established since 2014 with a variety of perennials that can supply nectar and pollen over the year and especially during the prolonged flower season. The three orchards where the gardens are established each exceed 40 ha. Gardens have been established in just one portion of the orchards, so that flower visitation can be assessed near and far from the gardens. The individual visitation activity of flower visitors was evaluated per unit time and their abundance on avocado flowers near the gardens and away from the gardens. Visitation was also similarly assessed on the pollinator gardens. Pan traps were also used to assess the presence of native bees in the orchards.
The most abundant visitors in all years have been Syrphid spp. along with a variety of other flies and wasps. The most abundant native bee species have included Ceratina, Halictus, Agapostemon and several andrenid species. The highest diversity and abundance of visitors has occurred after the high rainfall year of 2016/17 after previous drought years.
Read more at:
http://ceventura.ucanr.edu/newsletters/Topics_in_Subtropics76791.pdf
- Author: Beth Grafton-Cardwell
What Are the Ag Experts Talking About?
Event Name | Date |
---|---|
UC Ag Expert talks about citrus thrips | 10/17/2018 |
What is involved in the webinars?
A series of 1 hour webinars will highlight various pest management and horticultural topics for citrus and avocados. During each session, a UC Expert on the subject will make a presentation and entertain write-in questions via chat during and/or after the presentation. As we develop this program, we may expand to other crops. These programs are open to all, but are geared to those individuals, such as PCAs and Growers who need CEUs.
Topics: pests and diseases of citrus and avocados
What are the topics and how do I register?
Citrus Thrips - October 17, 2018 at 3 pm
Register in advance for this webinar by clicking on the event link above.
Are there Continuing Education units?
When the subject discusses pest or disease management, continuing education units will be requested from DPR (1 unit per session). Participants will pre-register, participate in the webinar and be awarded the unit. The sessions will be recorded and hosted on this web site for future study. However, continuing education units will be awarded only to the participants who attend the live version of the webinar.
Who is involved?
This webinar series is brought to you by Ben Faber (UC ANR Ventura Advisor) and Dr. Beth Grafton-Cardwell (Depart of Entomology UC Riverside Extension Specialist) with the technical support of Petr Kosina (UC IPM Contect Development Supervisor) and Cheryl Reynolds (UC IPM Interactive Learning Developer).
https://ucanr.edu/sites/ucexpertstalk/
Photo: The mighty citrusthrips - Scirtothrips citri
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