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

Posts Tagged: organic

Make More Avocado Fruit

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.

TreatmentTotal FruitNet Increase (%)Large fruit (213-354 g/fruit)Net increase (%)
 lb fruit/tree
GA3           74.7 az             84           34.3 a              128
Control            40.6 b             15.0 b  
P-value 0.0997   0.0657  

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
TreatmentTotal FruitNet 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  
P-value 0.0029   0.0037  
GA3         215 a             76          141 a            70
Control          122 b              83 b  
P-value 0.0042   0.0026  

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.

TreatmentTotal FruitNet Increase (%)Valuable size fruit (178-325 g/fruit)Net increase (%)Large fruit (213-354 g/fruit)Net increase (%)
 lb fruit/tree
GA3       408.1 az         10      379.4 a            13       294.1 a           16
Control       372.6 b        335.3 b         253.3 b  
P-value 0.0626   0.0252   0.0626  

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

avocado fruit
avocado fruit

Posted on Thursday, April 19, 2018 at 7:23 AM
Tags: avocado (289), gibb (3), gibberelic acid (1), gibberellin (2), growth promoter (1), organic (12), PGR (5)

Organic Blueberries Make More Money

Synopsis of: “The Organic Premium for California Blueberries” by Hoy Carmen, professor emeritus in the Agricultural and Resource Economics Dept., UC Davis

Commercial-scale production of blueberries in California is a relatively recent development. California first reported blueberry statistics in 2005 when there were 1,800 acres of blueberries harvested and production of 9.1 million pounds with a total value of $40.58 million. Harvested acres increased to 3,900 acres in 2010 with production of 28 million pounds and a total value of $75.98 million. Growth continued through 2015 with California Agricultural Statistics Survey (CASS) reporting 5,700 acres of blueberries harvested, production of 62.4 million pounds, and total value of $116.98 million.

California blueberries are shipped throughout the U.S. and to a number of export destinations. During the 2016 harvest, California's largest U.S. market was California, which accounted for 34.75% of California's total fresh blueberry shipments of 46,493,407 pounds.

The largest out-of-state domestic shipments were to Texas, Oregon, Washington, Arizona, New York, Minnesota, Utah, and Pennsylvania. These states collectively accounted for 36.54% of California shipments. Canadian shipments of 5.54 million pounds accounted for 11.9% of California's volume and made up 67.1% of exports.

Typically, the price per pound of organically grown blueberries is higher than for conventional production. Prices also vary by package size, with smaller package sizes usually selling for more per pound than larger packages. There is usually a premium for the first portion of the crop-marketing year, and the overall level of prices will vary by year. Prices can also be expected to vary by geographic location. California organic blueberries are among the first domestic fruit on the market when prices tend to be seasonally high.

Growth in California organic blueberry production has outpaced conventional production for several years, and California accounted for about half of the U.S. supply of organic blueberries in 2014. The organic share of California blueberry shipments in 2016 was 23.1% in terms of volume and 34.8% in terms of value. The larger share of value is due to the premium price for organic blueberries.

The organic premium, which averaged $2.28 per pound in both 2015 and 2016 (78–79% of the conventional fresh blueberry price), varies by package and over time. California has some of the earliest domestic blueberry production, with relatively high prices for both conventional and organic blueberries at the beginning of the season. The proportion of shipments that are organic decreases as the season progresses and the organic premium tends to be highest after the first one-third of the season. The growth of organic blueberry production in California, relative to overall California production as well as U.S. organic blueberry production, seems to indicate a comparative advantage for organic blueberries in California. Further growth of organic as well as total blueberry production in California is expected.


For the full article see:

Organic production costs, South Coast

Conventional costs, South Coast

Conventional, San Joaquin Valley

Report on US Organic Sales, 2016


Blueberry fruit
Blueberry fruit

Posted on Friday, October 6, 2017 at 7:20 AM
Tags: blueberry (7), California (13), conventional (2), costs (1), development (1), organic (12), prices (1), production costs (2), sales (3)

California Testing Finds Little or No Pesticide Residues on Most Fruits and Vegetables in 2015

Out of 3,600 samples of 145 fresh fruits and vegetables tested in California in 2015, just 43 had pesticide residue over legal limits, and 113 contained residue of a pesticide not approved for that commodity. Pesticide residue limits are set based on legal use of the product and violations are generally not health concerns.‚Äč

The tests were conducted by the California Department of Pesticide Regulation, which for three decades has been conducting one of the most comprehensive pesticide monitoring programs in the country.

Other highlights from the just-released results:

  • 39.8% (1,434 of 3,600 samples) had no pesticide residues detected.
  • 55.8% (2,010 of 3,600 samples) had one or more detected pesticide residue less than or equal to established tolerances. 

As in recent years, the majority of these samples had residues at less, usually much less, than 10% of the tolerance level.

The department also tested 170 fruits or vegetables labeled organic and 85.3% had no detectable pesticide residue, 11.8% had residues acceptable under organic regulations, 2.4% had residues acceptable in conventionally grown produce but not organic, and 0.6% had unacceptable residues.

Certain products from China and Mexico had the highest level of illegal pesticide residues detected.

See the testing data

   Newsletter of the Western IPM Center                                      January 2017

fruits veg
fruits veg

Posted on Wednesday, January 4, 2017 at 8:50 AM
Tags: agriculture (13), contaminants (1), conventional (2), fruits (3), organic (12), pesticides (26), residues (2), vegetables (2)

Organic Control of Asian Citrus Psyllid is Challenging

With the detection of Huanglongbing (HLB) in California in 2012 and 22 additional cases reported during 2015 through June 2016 there is a major concern among citrus growers about the spread of this incurable bacterial disease. The vector of the disease, the Asian citrus psyllid (ACP), is a hardy insect with good dispersal capabilities and can be found in many southern California citrus groves today. With no direct cure for HLB at present, the only option for growers to combat the disease is to control the psyllid. This can prove difficult for conventional citrus growers with broad spectrum insecticides, but for organic citrus growers, which grow an estimated 7% of citrus in California, the task is even more difficult with the currently available options.

Entrust (spinosad) + oil, Pyganic (pyrethrin) + oil, and oil alone are currently the recommended and most widely used insecticide options for organic growers (UC IPM Guidelines for Citrus). While these insecticides are fairly effective in killing ACP if they make direct contact, the residual life of these pesticides is very short (days) compared to conventional insecticides (weeks to months). For example, in our petri dish studies, 10 fl oz/acre Entrust SC + 0.25% Omni supreme spray oil caused 89% mortality, 17 fl oz/acre Pyganic 5.0 EC + 0.25% Omni supreme spray oil caused 73% mortality and 0.25% Omni supreme spray oil caused 42% mortality when 1st-2nd ACP nymphs were exposed to treated leaves one day after application. Nymphal mortality continued to decline for the Entrust + oil treatment (69% mortality) and even more severely declined for Pyganic + oil (27% mortality) 3 days after treatment. In contrast, one-day-old residues of a conventional insecticide, the neonicotinoid 5.5 oz Actara (thiamethoxam), resulted in more than 95% mortality of nymphs and mortality remained high for more than a month.

Studies of grower orchard treatments confirmed laboratory studies that showed a short residual effect of organic treatments (Entrust + oil and oil alone) compared to conventional insecticides (Actara). We monitored changes in population densities of ACP (adults by tap, nymphs and eggs by flush examinations) in the fall of 2015 before and after a grower sprayed separate orchards with one of three insecticides; 1) 1.25% 440 Supreme Spray Oil by ground application (400 gpa), or 2) 9 fl oz Entrust SC + 1% oil by air (50 gpa), or 3) 5.5 oz Actara by air (50 gpa). The oil treatment had little effect on the adult population, but significantly reduced psyllid nymph densities for 17-24 days. Entrust was completely ineffective in controlling psyllid nymphs, but suppressed adult and egg populations for about 14 days. Actara, a conventional insecticide, was the most effective treatment in the study and provided more than 5 weeks of both adult and nymph control. Because of the short residual effect of organic insecticides in citrus, repeat treatments are needed at a frequency of about every 2 weeks for ACP control.  

Tamarixia radiata wasps released for biological control of ACP provide 20% to 88% parasitism depending on geographical location and time of year. If there were no disease to be concerned about, this level of parasitism by Tamarixia would be sufficient to protect citrus from the feeding damage of the psyllid. However, the disease spreads rapidly with just a few psyllids and so a greater level of control is needed. Generalist predators, such as lady beetles, lacewings and assassin bugs, also assist with control. Argentine ants can severely disrupt this parasitism by protecting psyllids from natural enemies. Unhappily, Entrust + oil, thought of as a very selective insecticide combination, was found to be highly toxic to adult Tamarixia wasps exposed to 3 day old residues. Thus, the organic insecticide that is the best for controlling the psyllid pest is not compatible with the parasitoid natural enemy, limiting our ability to use integrated strategies to control the psyllid.

At present, it is not mandatory, but is strongly recommended, that all southern California citrus growers treat their orchards in an area wide manner. The area wide program consists of coordinated treatments twice a year (winter and fall), and additional treatments in between. Due to the short residual nature of organic insecticides, organic applications should be applied twice within 10-14 days of each other for every single conventional insecticide application. This is especially important for younger groves as ACP nymphs thrive in new flush. Organic growers have a tough decision to make between treating frequently for ACP and the high cost associated with those treatments or transitioning into conventional management in order to more effectively control ACP. Additional solutions are needed for organic citrus.

UC IPM Guidelines for Citrus: Asian Citrus Psyllid.

ACP adult and nymph
ACP adult and nymph

Posted on Monday, July 25, 2016 at 4:57 AM
  • Author: Nastaran Tofangsazi and Beth Grafton-Cardwell, Department of Entomology, UC Riverside
Tags: ACP (86), actara (1), Asian Citrus Psyllid (57), entrust (2), HLB (71), huanglongbing (66), insecticides (2), neonicotinoid (1), oil (3), organic (12), pesticides (26), pyganic (1), Tamarixia (5)

New Contact Herbicide Trials

There has been more than the usual number of questions about what I am calling "bio-based" herbicides recently. Arguably, this is coming from news that some school districts and cities specifically calling out the use of glyphosate on the properties they manage.  Landscaping departments want to know which of the products available work the best.

To start, please be aware that all of these products are contact herbicides that will not move through the plant. Therefore, they will not be effective if you are trying to get to any underground organ such as the roots, rhizomes, tubers, etc. of any perennial plant. Do not try to make a head to head comparison to glyphosate - glyphosate will win every time.  These act more like diquat (Reward) so if you are using Reward, some of these could be a good replacement, if needed.

 Here's what I have in:





















Roundup Pro


*listed as “organic” but not necessarily OMRI certified

**listed as a biopesticide

 I also tried A.D.I.O.S. (active ingredient:  sodium chloride + other ingredients: potassium chloride, sodium bicarbonate) in a preliminary experiment and found that it was a waste of my time.

 The rates for most of these can be quite high. For example, WeedPharm is applied with no dilution even though it carries a “Danger” signal word on the label. Other are applied at 3-25% rates by volume.


Posted on Friday, July 1, 2016 at 6:33 AM
  • Author: Cheryl Wilen - Area Wide IPM Advisor
Tags: bio-basedk (1), contact (1), herbicides (18), organic (12), pesticides (26)

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