Posts Tagged: olive
Pre-bloom foliar boron application on olive may improve yield
Olive orchards entering an OFF year in 2024 may benefit from pre-bloom foliar boron (B)...
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UCCE San Diego advisor educates growers on complex water regulations
‘Ag Order' for San Diego County expected to be enforced by end of 2023
Generally known for its steady warmth and picturesque beaches, San Diego County is also home to nearly 5,000 small farms and is an economic hotspot for nurseries and floriculture. But the great diversity of ornamental crops that dominate the growing region and complexity of regulations make compliance challenging for growers, some of whom grow over 400 crop varieties.
“The regulatory environment for the growers is still complicated and overwhelming because, along with the Regional Water Board, growers are regulated by the County of San Diego,” said Gerardo “Gerry” Spinelli, University of California Cooperative Extension production horticulture advisor for San Diego County.
To help growers with compliance, Spinelli is prioritizing education and expanding growers' knowledge. By partnering with organizations such as the Farm Bureau of San Diego County and the San Diego Region Irrigated Lands Group, Spinelli works to reach more than 1,200 growers, supporting them as they navigate regulatory agencies.
Formally referred to as the Regional Water Quality Control Boards, the Regional Water Board aims to develop and enforce water quality objectives and implement plans to protect the beneficial uses of California's waters.
A unique place to grow in California
About 10 years ago, the Regional Water Board created the Agricultural Order (Ag Order), a set of rules outlining how growers manage water discharge from agricultural operations.
The new Ag Order for San Diego County, expected to be enforced by the end of 2023, will focus on nitrogen management and groundwater quality. However, new considerations are needed to address the variety of crops grown by a single farmer, a common practice in San Diego.
Calculating nitrogen input and output for more than 400 crop varieties is not feasible for small farmers, a challenge exacerbated by the meticulous attention needed for San Diego's high-end specialty crops like ornamentals, native plants and specialty fruit.
Furthermore, many San Diego growers have limited expertise and experience because they are entering agriculture as a second or third career. Many have become “accidental growers” in that they purchased land with a preexisting avocado or cherimoya grove, for example.
To help address these challenges, the grower community is emphasizing the need for more educational opportunities that are accessible and relatable.
Equipping growers through education
Enrico Ferro, president of the San Diego Region Irrigated Lands Group – a third-party entity that manages water sample testing on behalf of growers – has relied on Spinelli's teaching to “bridge the gap” for growers, including himself.
“Gerry has been great because he has expertise in nurseries, but the educational content he creates is relevant to all growers,” said Ferro, who is an avocado and citrus grower in San Diego's North County.
Spinelli, who specializes in containerized production in nurseries and floriculture, has been instrumental in providing technical assistance to growers since he joined Cooperative Extension in 2020.
“I started teaching over Zoom since I became an advisor during the pandemic, and I try to cover different topics for each training,” Spinelli said, adding that he teaches in English and Spanish, making his content more accessible to the grower community in San Diego.
For in-person educational opportunities, Spinelli created the “Last Wednesday” monthly meetings hosted at the Farm Bureau of San Diego County, which brings together growers and other agricultural experts to learn from one another.
“We try to get our information out in creative ways and Gerry is instrumental in that. He's our primary source of really wonderful information delivered in an engaging way,” said Tasha Ardalan, program coordinator for the SDRILG. “He's proactive and is always willing to try new things, too.”
Planning for San Diego's agricultural future
Currently, the Ag Order is modeled around regulations for the Central Valley. As conversations and planning for San Diego County continue, Spinelli is supporting the Regional Water Board with information on nurseries and greenhouses in hopes that the final Ag Order will better serve San Diego growers.
“I'm trying to help others understand how nursery and greenhouse production systems function, and how and why they are different from an almond orchard or tomato field in Fresno,” explained Spinelli.
Michael Mellano, CEO of Mellano & Company, a fresh cut flower grower and distributor in Oceanside, feels the impact of the Ag Order and its failure to account for variability. Growing over 100 varieties of flowers, Mellano said that for several plants there is little scientific research on how much nitrate to apply.
“Farmers want to do a good job. We make mistakes and we try to fix them as quickly as we can, and we try to educate others on what works,” said Mellano, who is also a member of the SDRILG.
Growers like Mellano and Ferro agree that the farming community in San Diego needs to be given the latitude to solve problems within their means, an ability that requires an understanding of San Diego's uniqueness.
“San Diego is significantly different, and we need an Ag Order that is reflective of our differences,” said Valerie Mellano, SDRILG consultant and former UCCE environmental issues farm advisor. “In developing the new Ag Order, there's a huge opportunity for education and research, something that we know Gerry can easily do and continue to support us in.”
Thus far, Spinelli's educational content has reached two-thirds of SDRILG's 1,200 members. In addition to the live training sessions, growers can watch videos that cover topics such as evapotranspiration, irrigation distribution uniformity, water quality indicators and more on Spinelli's YouTube channel.
Since the Ag Order requires all growers to complete two hours of water-quality education, the SDRILG has agreed to apply one hour of credit to growers who attend a one-on-one session with Spinelli.
As San Diego's growers continue to leverage educational opportunities – whether it's alongside Spinelli, SDRILG or learning from one another – Spinelli emphasized that their success also relies on an ag order that adheres to a distinctive landscape, multitude of specialty crops and growers with varying expertise.
/h3>Fertilizing Olives
Developing a nitrogen fertilizer plan for olive orchards
Elizabeth J. Fichtner, Farm Advisor, UCCE Kings and Tulare Counties
Nitrogen management plans (NMP) for California olive orchards are essential for the Irrigated Lands Regulatory Program and can increase net return. A good NMP has the potential to increase yield, improve oil quality and mitigate biotic and abiotic stresses while reducing nitrogen losses from the orchard.
Olives differ from other orchard crops in California in that they are both evergreen and alternate bearing. Individual leaves may persist on the tree for two to three years. Leaf abscission is somewhat seasonal, with most leaf drop occurring in late Spring. Rapid shoot expansion occurs on non-bearing branches during the hottest part of the summer (July-August) on ‘Manzanillo' olives in California. The fruit on bearing branches limits current season vegetative growth. Olives bear fruit on the prior year's growth, and the alternate bearing cycle is characterized by extensive vegetative growth in one year followed by reproductive growth the following year (Figure 1). With bloom occurring in late April to mid-May, fruit set can be estimated in early July, allowing for consideration of crop load while interpreting foliar nutritional analysis in late July-early August.
Critical Nitrogen Values. Foliar nitrogen content in July/August should range from approximately 1.3-1.7% to maintain adequate plant health. The symptoms of nitrogen deficiency manifest when foliar nitrogen content drops to 1.1% nitrogen. As leaves become increasingly nitrogen deficient, foliar chlorosis progresses from yellow/green to yellow. Leaf abscission is common at nitrogen levels below 0.9%. Nitrogen deficiency in olive is associated with a reduced number of flowers per inflorescence, low fruit set, and reduced yield.
Excess nitrogen (>1.7%) adversely affects oil quality. Oil with low polyphenol concentration is associated with orchards exhibiting excess nitrogen fertility. Since polyphenols are the main antioxidant in olive oil, reduced polyphenol levels are associated with reduced oxidative stability.
Nitrogen content may impact orchard susceptibility to biotic and abiotic stresses. For example, while excess nitrogen content has been associated with increased tolerance to frost prior to dormancy, in spring (post-dormancy) it is associated with sensitivity to low temperatures. High nitrogen content has also been associated with increased susceptibility to peacock spot, a foliar fungal disease on olive.
Foliar Sampling for Nitrogen Analysis. By convention, foliar nutrient analysis is conducted in late July-early August in California. Fully-expanded leaves are collected from the middle to basal region of the current year's growth at a height of about 5-8 feet from the ground. To capture a general estimate of the nitrogen status of the orchard, samples should be taken from 15-30 trees, with approximately 5-8 leaf samples collected per tree. Leaves for analysis should only be collected from non-bearing branches. Growers may find it beneficial to make note of the ON and OFF status in the historical records of each block. The orchard bearing status, combined with anticipated yield and foliar analysis will guide decisions for nitrogen applications the following year.
Distribution of nitrogen in the olive tree. Over 75% of the aboveground nitrogen in the olive tree is incorporated in the vegetative biomass (Figure 2). The twigs, secondary branches, main branches, and trunk account for approximately 33% of aboveground nitrogen (Figure 2). Twenty-three percent of the aboveground nitrogen is harbored in the fruit, with the majority in the pulp (19%) (Figure 2). Fruit is only an important nitrogen sink during the initial phase of growth. As fruit size increases, the N concentration decreases due to dilution.
Estimation of nitrogen removed from the orchard. The easiest component of orchard nitrogen loss to estimate is the nitrogen in the harvested fruit. A ton of harvested olives removes approximately 6-8 lbs of nitrogen from the orchard. The quantity of nitrogen in the fruit varies slightly between olive varieties (Table 1). Growers can use the Fruit Removal Nutrient Calculator for Olive on the California State University, Chico (CSU Chico) website to gain estimates of N removal by the three oil varieties (Arbequina, Arbosana, and Koroneiki), and the Manzanillo table olive. This tool was developed by Dr. Richard Rosecrance (Professor, CSU Chico) and Bill Krueger (Farm Advisor, UCCE). To access the Fruit Removal Nutrient Calculator for Olive, visit the following URL:
http://rrosecrance.yourweb.csuchico.edu/Model/OliveCalculator/OliveCalculator.html
Pruning may generate a second component of nitrogen loss from orchards. The best practice to mitigate nitrogen loss from pruning is to reincorporate the pruned material into the orchard floor by flail mowing. The nitrogen in this organic material will gradually become available to the trees through mineralization.
In mature orchards, the wood removed by annually pruning is approximately equal to the annual vegetative growth. Consequently, the input and removal of nitrogen in vegetative growth is cyclic and almost equal in mature orchards. In young orchards, nitrogen inputs are utilized to support vegetative growth and little nitrogen is removed from the orchard in prunings or crop. During this time nitrogen must be supplied to meet the demand to support vegetative growth. It is estimated that approximately 2.5 lbs nitrogen is required to produce 1,000 lbs. fresh weight of tree growth.
Nitrogen Use Efficiency. Not all the nitrogen supplied to the orchard from fertilizer and other inputs (ie. organic matter, irrigation water) is utilized for tree growth and crop production. A fraction of nitrogen is lost from the orchard ecosystem through processes such as runoff, leaching, and denitrification. Efficiency varies among orchards, with some orchard systems exhibiting higher nitrogen utilization rates than others. The efficiency generally varies from 60% - 90%. Higher values denote more efficient use of nitrogen inputs. To estimate the amount of nitrogen to supply an orchard, the demand is divided by the estimated efficiency. For example, if nitrogen demand is 50 lbs. per acre and efficiency is estimated at 0.8, then 62.5 lbs. of nitrogen per acre should be applied.
Summary. Nitrogen management plans are site-specific and designed to meet orchard and crop demand while reducing environmental losses. Nitrogen utilization is never 100% efficient. Nitrogen use efficiency can be maximized by minimizing losses from irrigation and fertilization practices while utilizing foliar analysis and knowledge of alternate bearing status to fine-tune applications.
Select References:
Fernández-Escobar, et al. 2011. Scientia Horticulturae 127:452–454.
Hartman, H.T. 1958. Cal Ag. Pgs 6-10.
Rodrigues, M.A. et al. 2012. Scientia Horticulturae 142:205-211.
The Achemon Sphinx Moth: A Lovely Beast, Indeed
It is indeed a “lovely beast,” as lepidopterist Art Shapiro, UC Davis...
Eumorpha achemon, the Achemon Sphinx, is a "lovely beast," says UC Davis distinguished professor Art Shapiro. Ann Sievers, owner, grower and miller Il Fiorello Olive Oil Co., recently found this one the wall of her patio. (Photo by Ann Sievers)
What's for lunch? A chicken in one of Ann Sievers' flocks at Il Fiorello Olive Oil Co., eyes the photographer. Chickens eagerly eat lots of bugs--if they're available. The larvae of the Achemon Sphinx moth feed on grape leaves. (Photo by Kathy Keatley Garvey)
Naturalist-photographer Greg Kareofelas took this image of an Eumorpha achemon larva in his yard in Davis several years ago. It was feeding on native grape, Vitus californica. (Photo by Greg Kareofelas)
An adult Eumorpha achemon, photographed by naturalist-photographer Greg Kareofelas in his yard in Davis several years ago. It was feeding on native grape, Vitus californica. (Photo by Greg Kareofelas)
Unusual and Uncommon Fruits in the Garden
By Susanne von Rosenberg, U.C. Master Gardener of Napa County After you have been gardening a...
Calif Rare Fruit Growers (crfg.com)
UC IPM (UC ANR) http://ipm.ucanr.edu/
The Home Orchard (UC ANR) http://homeorchard.ucanr.edu/
UC Fruit and Nut Research (UC Davis) http://fruitsandnuts.ucdavis.edu/
UC VRIC (UC Davis) https://vric.ucdavis.edu/
CNPS (cnps.org) https://www.cnps.org/