UC Ag Experts Talk: Use of Plant
Growth Regulators on Citrus
August 19, 3-4:30 PM
Dr. El-kereamy will discuss the use of plant growth regulators that are registered for use on California citrus to increase fruit set, prevent fruit senescence, control preharvest fruit drop, and to control suckering. One DPR CE unit (other) and one CCA CE unit (IPM) were requested.
Ashraf El-kereamy has been named the new director of UC Agriculture and Natural Resources' Lindcove Research & Extension Center, he took on this additional role as of July 1, 2020. He will continue to serve as a UC Cooperative Extension specialist in the Department of Botany & Plant Sciences at UC Riverside and will be based at the Lindcove Research & Extension Center.
Remembering UCR's Dr. Charlie Coggins
(Remembrance courtesy of the California Citrus Quality Council)
It is with deep sadness that we learned that Charles W. Coggins, Jr. passed away on Aug 18, 2019 at the age of 88.
Coggins was an industry pioneer who recognized the potential advances with plant growth regulators (PGRs), beginning with gibberellic acid (GA) and continuing with programs to retain 2,4-D. It was said that his research on PGRs has been described as the single most economically beneficial research result of the last century. He authored more than 100 technical publications and nearly 50 semi-technical publications that have proved to be invaluable tools for citrus growers worldwide. He was the recipient of numerous awards for his leadership, agricultural excellence and research accomplishments.
Charlie, Professor Emeritus of Plant Physiology, officially retired from the University of California Riverside in 1994. During his 37 years at the University, he served as Chairman of the UC Riverside Department of Plant Sciences and helped create the Department of Botany and Plant Sciences. He also served 15 years as Executive Secretary/Treasurer for the International Society of Citriculture. To help succeeding generations of researchers, Coggins created The Coggins Endowed Scholarship Fund at UCR to provide financial assistance for graduate students in the College of Natural and Agricultural Sciences who demonstrate academic excellence, quality research and benefit to the citrus industry.
He served as Chairman of the Board of Directors for the CA Citrus Quality Council from Nov 1992 to Jan 2008. In 2003, he was presented with CCQC's highest honor, the Albert G. Salter Memorial award which recognizes and individual who has made outstanding contributions to and achievements in the citrus industry.
Charlie was born November 17, 1930 in North Carolina. He was proceeded in death by two sons from cystic fibrosis. He is survived by his wife Irene of 68 years, a son and four grandchildren. A memorial service is pending. In lieu of flowers, contributions can be made to support his scholarship at UCR in honor of him, to the Parkinson's disease foundation or cystic fibrosis charities. Cards can be sent to 819 Alden Road, Redlands, CA 92373.
The family of Dr. Charlie Coggins would like to welcome all
citrus industry friends to attend his memorial service.
September 7, 2019 | 2:00 PM
First Baptist Church
51 West Olive Avenue
Redlands, California 92393
Use of ProgGibb LV Plus® Plant Growth Regulator Increases Total Yield/ Fruit Size of Hass Avocados
As of March 27, 2018, foliar application of GA3 (ProGibb LV Plus®, Valent BioSciences, Corp.) to ‘Hass' avocado trees in commercial orchards has been approved. Dr. Carol J. Lovatt, emerita professor of plant physiology at the University of California – Riverside, recently completed research concerning the effectiveness of ProGibb LV Plus® on avocado fruit size and yield. A summary of her research — including best practices — follows.
Application Best Practices
ProGibb LV Plus® should be applied as a foliar spray when 50 percent of the trees in a block are at the cauliflower stage of inflorescence. If a grower cannot make an application at this time, it is best to apply the spray later, rather than earlier in order to ensure effectiveness.
The spray should be applied like a pesticide spray — full canopy coverage with a focus on the inflorescences. Those applying the spray should avoid spraying to run-off.
The ideal dilution for ground application is 12.5 fluid ounces of ProGibb LV Plus® (25 grams active ingredient [gai]) per 100 gallons of water/acre. For aerial application, use 12.5 fluid ounces (25 gai) in 75 gallons of water/acre. According to the research, the ideal application rate is 25g GA3 per acre; higher and lower doses were less effective. The pH of the water used should be adjusted such that the final pH of the spray solution is between pH 5.5 – 6.0.
Dr. Lovatt utilized organosilicone surfactant Silwett L-77® or Widespread Max® at a concentration of 0.05 percent as a wetting agent. Similar pure organosilicone type surfactants would be acceptable as wetting agents. It is important to note that until additional research can be conducted, other materials should not be included in the ProGibb LV Plus® spray solution.
Effect of ProGibb LV Plus® (GA3)
Dr. Lovatt's research team tested the effect of ProGibb LV Plus® on fruit size and yield for both ground and aerial applications. Overall, the research team noted that GA3 had no negative effects on ‘Hass' avocado fruit quality.
Ground applications were tested in March at groves located in Corona, Irvine and Somis, California. The tests were run on Duke 7 clonal rootstock trees at the cauliflower stage of inflorescence development. Each of the groves reported net increases in total yield and large/commercially valuable size fruit. The results were as follows:
Table 1. Effect of GA3 (25 g ai/acre) applied at the cauliflower stage of inflorescence development on yield and fruit size (pounds/tree) of ‘Hass' avocado trees in Corona, CA.
|Treatment||Total Fruit||Net Increase (%)||Large fruit (213-354 g/fruit)||Net increase (%)|
|GA3||74.7 az||84||34.3 a||128|
|Control||40.6 b||15.0 b|
z Values in a vertical column followed by different letters are significantly different at specified P-values by Duncan's Multiple Range Test at the P-values indicated. (From the work of Salazar-García and Lovatt, 2000).
Table 2. Effect of GA3 (25 g ai/acre) applied at the cauliflower stage of inflorescence development on yield and fruit size as pounds and number of fruit per tree in an alternate bearing ‘Hass' avocado orchard in Irvine, CA.
|Year 1 Yield|
|Treatment||Total Fruit||Net Increase (%)||Valuable Size Fruit (178-325 g/fruit)||Net increase (%)|
|GA3||92.2 az||70||67.9 a||65|
|Control||54.2 b||41.2 b|
|GA3||215 a||76||141 a||70|
|Control||122 b||83 b|
z Values in a vertical column followed by different letters are significantly different at specified P-values by Duncan's Multiple Range Test at the P-values indicated. (From the work of Lovatt and Salazar-García, 2007; Zheng et al., 2011)
Table 3. Effect of GA3 (25 g ai/acre) applied at the cauliflower stage of inflorescence development at on yield and fruit size of ‘Hass' avocado trees in Somis, CA. Percent net increase reflects the benefit of GA3 at 25 g ai/acre relative to the untreated control trees.
|Treatment||Total Fruit||Net Increase (%)||Valuable size fruit (178-325 g/fruit)||Net increase (%)||Large fruit (213-354 g/fruit)||Net increase (%)|
|GA3||408.1 az||10||379.4 a||13||294.1 a||16|
|Control||372.6 b||335.3 b||253.3 b|
z Values in a vertical column followed by different letters are significantly different by Fisher's Protected LSD test at the P-values indicated.
Overall, ground application of GA3 resulted in a net increase of 3,905 lb/acre, with a net increase of 4,851 lb/acre of commercially valuable size fruit (packing carton sizes 60+48+40; 178-325 g/fruit) and a net increase in large fruit (packing carton sizes 48+40+36; 213-354 g/fruit) of 4,488 lb/acre.
Aerial applications were tested on groves located in Pauma Valley and Carpinteria, California. Together, the aerial applications demonstrated that GA3 increased fruit set (fruit retention) by 55 percent into the last week of August and fruit size by 6 percent through mid-August.
Ultimately, Dr. Lovatt's research indicates that use of GA3 could result in substantial increases in net dollar return per acre to the grower due to increase in yield and commercially valuable size fruit. In addition, growers whose avocado groves are not suited to ground applications (groves located on slopes or in high-density formations) can benefit from the efficacy of utilizing aerial applications. In summary, ProGibb LV Plus® is “vital to the California avocado industry to increase grower income per acre to help sustain the California avocado industry.”
N.B. Remember, only well managed trees are going to respond. This will not turn around a poor producing orchard. only potentially increase production on an already good producing orchard. Ben
The California Avocado Commission is pleased to announce the availability of ProGibb LV Plus Plant Growth Regulator Solution (gibberellic acid) for use on avocados in California under a Special Local Needs (SLN) registration effective March 27, 2018. ProGibb has been shown to effectively increase fruit size and set when applied at the cauliflower stage of bloom.
ProGibb LV Plus can be applied from the ground or by air. Ground applications should be made by mixing 12.5 fluid ounces of product in 100 gallons of water per acre. Aerial applications should be made by mixing 12.5 fluid ounces of product in 75 gallons of water per acre. Only one (1) application is allowed per year.
The restricted entry interval (REI) is 4 hours, and the preharvest interval (PHI) is 0 days, so ProGibb LV Plus can be used with minimal disruption to harvesting and other grove management activities.
- A copy of the SLN Label must be in the possession of the user at the time of application.
- The signature of the County Agricultural Commissioner or their designee must be obtained prior to the use of ProGibb LV Plus.
- This SLN is only valid for the ProGibb LV Plus product manufactured by Valent BioSciences Corporation. Generic gibberellic acid products may not be used under this SLN.
The California Avocado Commission wishes to thank Dr. Carol Lovatt, University of California Riverside, for her many years of dedicated research that made this registration possible. We also thank the many growers, PCAs, and pesticide applicators who participated in the research trials.
If you have any questions about this SLN registration and the use of ProGibb LV Plus, please consult with your local PCA or you may contact Tim Spann at firstname.lastname@example.org.
Photo: Cauliflower stage of flowerr/span>
Growers are faced with an ever-changing list of commercial “tools”, each with the promise of providing some advantage to the farmer. Frequently, these are new fertilizer mixes presented as proprietary cocktails promoted and dispensed with promises of a multitude of profitable (yet improbable) benefits to the buyer. With the large number of new products available, and the number of salespeople promoting them, it is often difficult for growers to distinguish between products likely to provide real benefit, and those that may actually reduce the profitability of the farm.
In all situations when a company approaches the University or a commodity research board with a new product or technology for sale to California growers, these institutions act as grower advocates. They are charged with sorting through the available information; asking the right questions; getting the necessary research done if the available information warrants this pursuit; disseminating accurate information on these new technologies and products, and doing all that can help maximize grower profits now and in the future. When approached with a new product or technology it is obligatory to challenge claims with the following questions:
Is there some basic established and accepted scientific foundation on which the product claims are made?
Language that invokes some proprietary ingredients or mysterious formulations, particularly in fertilizers mixes registered in the State of California, raises red flags. A wide range of completely unrelated product benefit claims (such as water savings, pesticide savings, increased earlier yield) raises more red flags. Product claims that fall well outside of any accepted scientific convention generally mean the product is truly a miracle, or these claims are borderline false to entirely fraudulent. Some of the water treatment products on the market fall into this category and can easily be checked against some of the studies found at this site: http://www.chem1.com/CQ/index.html
Has the product undergone thorough scientific testing in orchards?
Frequently, products are promoted based on testimonials of other growers. While testimonials may be given in good faith, they are most often not backed up by any real scientific testing where a good control was used to compare orchard returns with and without the product.
A “test” where a whole block was treated with a product and which has no reliable untreated control does not meet accepted standards for conducting agricultural experiments. Also, a treated orchard cannot reliably be compared to a neighboring untreated orchard; and a treated orchard cannot be compared to the same orchard that was untreated the previous crop year. Even a test with half a block of treated trees and half untreated is not considered dependable by any known scientific standard of testing.
Only a well designed, statistically replicated, multi-year trial allows for direct comparison of untreated versus treated trees with statistical confidence. Verifiable data from tests that meet acceptable standards of scientific design, along with access to raw baseline (before treatment) yield data from the same trees (preferably for the two years prior) should be used to determine the validity of test results provided.
Are the test results from a reliable source?
If the testing were not done by a neutral party, such as university scientists, agency, or a reputable contract research company using standard scientific protocols, this raises red flags. If the persons overseeing the tests have a financial interest in seeing positive results from the product, it raises red flags.
Does the product have beneficial effects on several unrelated farm practices?
A product that increases production of trees, makes fruit bigger, reduces pests, reduces water use, and reduces fertilizer costs, is more than a little suspicious. In reality, if such a product really existed, it would not need any testing at all because its benefits would be so obviously realized by the grower community that it would spread rapidly by word of mouth and embraced by the entire grower community.
Are other standard and proven farm products put down in the new product sales delivery?
If a new product vendor claims that their product is taken up 15 times faster than the one growers are currently using, or is 30 times more efficient, it probably costs 15 to 30 times more per unit of active ingredient than the standard market price. Growers should always examine the chemical product label to see what active ingredient they are buying. There has to be a very good reason to pay more for an ingredient where previously there had been no problem supplying the same ingredient at a cheaper price to trees in the past.
So what is a grower to do ?
New products come and go. Snake oil products often disappear rapidly, when their efficacy fails to materialize after application. Products that confound their purported results with fertilizers or growth stimulators can persist, but eventually they too fail to live up to expectations at some point and will fade from popularity. Try to obtain some kind of consensus with university‐based research or other peer reviewed research reports, field efficacy trials that you run for yourself, and not on the testimonials of others. If you decide to conduct your own trials, they must be replicated and statistically analyzable, otherwise they are little more than anecdotal observations that have little value in quantifying the effects of a product or practice. For more help with trials, seek out University Extension advisors and specialists. This is their job, and they are willing partners in field research. After awhile, you will be able to ascertain the nature of the “oil” before you purchase it.