Solano County’s Stand Against Olive Fly

FEB 28, 2014

This is a synopsis of the olive fly meeting held on Feb 28, 2014 in Solano County. This represents information given to participants by experts in the field. As with any synopsis this does not constitute a complete coverage of the subject of olive fly and growing olives. It is always best to consult professionals about how to manage pests and chemicals, whether organic or not. We at IL Fiorello use professional support for assistance and information, as you should also. At the end of this article please see a partial list of resources for your support.


Albert Katz, Grower and Miller, Katz Farm


Patty Darragh, COOC
General Comments on Olive Oil Quality and Impact of OLFF to Markets.

Fly first reported in LA county 1997.  Generally the regional parks and landscape olives are not treated.  For the COOC almost 4% (2% previous years) of submitted oils are not meeting certification criteria this year for a variety of reasons, maybe olive fly, maybe early frost. The counties hardest hit with fly are Sonoma, Napa, Solano Co and San Diego Co.


Mike Madison, PhD, Grower and Miller, Yolo Bulb, Yolo, CA
Mark Sievers, Grower and Miller, IL Fiorello Olive Oil Co, Fairfield, CA
Impact and Information on Olive Fly and Milling Olives

Use irrigation control as the hot weather dehydrates olive fly so limit/control your irrigation. In 100°F weather don’t irrigate the trees.  Heat makes female flies inactive and you should carefully monitor temperature and humidity in grove. It is mandatory to do annual heavy pruning as the olive fly likes a dark damp quiet eg. no wind, environment.  Black scale likes that environment also. Black scale is a food source for olive fly. Very important to get the fruit off the tree each year so the fly does not overwinter in the “mummy fruit”.

Damaged or frozen fruit falls first so you may have a crop after the bad fruit falls off. But do not let the damaged infested fruit stay on the ground to over winter. It is reported that the fly has a 6 mile flying radius. Discuss your olives with your miller if you have questions or concerns. Transport of olive fly is not a generally accepted practice. Milling olive fly infested fruit is not good practice, and some mills will not accept olive fly infested fruit at all.


Louise Ferguson, PhD UC Davis
Life Cycle of Olive Fruit Fly and Implications for Control

Reviewed the biology of the fly, the Bactrocera oleae (Rossi) single host pest that only destroys olives and not the tree. She is recommending that yearly traps are set by March first. Dr. Ferguson referred to a 2009 study by Dr. Frank Zalom, UC Agricultural and Natural Resources, UC IPM online, and are peer reviewed articles.

There may be genetic differences and California may have a unique genetic variety but this has not been scientifically proven yet.


Dr. Ferguson showed a Dendogram cluster describing the fly cycle.

1. Adult olive fly
2. Egg in fruit
3. First instar (instar being the process of growth of the pupae)
4. Second and third instar
5. Third instar
6. Pupa in fruit

Females can live 11 months and may pupate in the ground. They have 3-5 generations per year and can pupate in the soil. So sanitation in the orchard is important. Disking and tilling the soil around the trees is valuable in controlling olive fly.

Mc phial trap:  Torula yeast is used in the Mc phial trap and is effective in capturing females because of the liquid especially with the addition of GF-120 to the container. Read the directions carefully and keep up with the trap maintenance.

The olive fly population is bimodal: spring and July August.

Control essential with:

1. Early season control NO host able olives.
2. Winter sanitation program
3. Preseason and throughout the season control with Spinosid GF-120 is critical.
4.  High heat over 100° F will kill first instars
5.  Mass trapping should never be done alone use Spinosid GF-120
6. Harvest as early as possible to miss fall generation.
7. Consider the use of Kaolin clay, which does not prevent photosynthesis but seems to be effective as a fly deterrent.



Danitol pyrethroid registered for use in 2012, is not organic. Valent technologies states that “Danitol is a synthetic pyrethroid that provides a powerful knockout punch for more than 100 of the most troublesome pests, including the invasive Brown Marmorated Stink Bug (BMSB). It is labeled for more than 120 crops—such as peach and other stone fruit, citrus, pome fruit (apples and pears), grapes, cotton, tomatoes, strawberries, peanuts, bushberries and blueberries. Unlike other synthetic pyrethroids, Danitol is proven not to flare mites and combines the effectiveness of both an insecticide and miticide.”

Dr. Ferguson states that “it is to be used only late in the season and only once, then return to GF-120.”  See the manufactures handout on their instructions for application of the product.

Spinosid resistance was an ongoing question, but the investigated ration is a resistance ratio of about 10.93. Which is described as quite low.


Resistance is a function of the total number of applications.  We don’t have a resistance problem now but we could.  Monitor the fruit as well as the traps. Danitol should be used only once and only late in the season. It is not organic. Use a HOBO data temperature and humidity monitoring station that displays real time data information. This is very useful in irrigation monitoring.  Set two traps per 5 to 10 acres in the orchard. Place them mid canopy in the shade in the north-east side of the tree.  Monitor weekly for catch.


 Jill LeVake, DOW Chemical
Considerations for use of GF-120 Spinosid in Controlling OLFF

Spinosid is an organic compound composed of sugars and protein. It has stabilizers to improve shelf life and humectants to prevent drying. The re-entry interval (REI) is 4 hours and the pre-harvest interval (PHI) is 3 days. Once mixed use that amount within one day, as it begins to deteriorate after being mixed. The use amount is 20 oz per acre per tree 2 to 3 ounces of the ratio based per tree.  The 1 to 1.5 dilution ratio results in little bait stations on each tree.  The use is about 20 ounces in 80 ounces of water. The nozzle stream is important, use a D 1 to D 2 size nozzle with no swirl plates or screens.  Almonds near olive orchards should be also treated and provide some synergistic effect for the olives. Put the traps out March first. Get them out early and monitor them. Then begin applications of GF-120 in April. Apply to every other row every 7 days.

Spinosid is pH sensitive 7.0 so mix with neutral water, and test well water if that is what you are using for diluent.



Jim Allen, Solano County Ag Commissioner
Regional Approaches to Pest control and Abatement

These are regional issues and proximity is really the issue.  Agricultural commissioner has the authority to supervise re abandoned orchards. This is a civil vs commercial issue.

Another pest is being monitored for progression, the olive psyllid is a relative of aphids and sucking insects.  Don’t bring fruit or fruit trees from Southern California to stop this infestation. If you do not want olives apply Fruit Stop at bloom or purchase Swann Olives that are non-bearing.


Dan Flynn, Executive Director of the UC Davis Olive Center
Future for Olive Fruit Fly control, Making New Tools Available

He stated that the goal of the center in multipurpose, including table olives and oil producing olives. He is dedicated to quality in all olives both table and olive oil and to research in both areas. There is funding and ongoing projects in both.

Please refer to the UC Davis IPM pest management site for great information.

He repeated the caution of using Danitol to use it only late in the season and then go back to GF-120. To research the use of Kaolin clay and referred to an article by Paul Vossen from 2006.

There is research being done regarding the olive fly

1. Kent Dane at UC Berkeley has a funded study on parasitoids with initial funding of $250,000.
2. USDA is investigating a male olive fly irradiation methods of sterilization.
3. Research in Spain is investigation a genetically engineered male olive fly study.
4. CDFA olive psyllid research ongoing
5. Frank Zalom researching GF-120 resistance in table olives.

Flynn also reminded everyone that there are years to come to have the research answers.

Olive center can be the distribution of information and he is placing articles on line for reference. Please find best practice information on line at the UCD Olive Center web site, and the IPM web site.



1. UC Davis Olive Center

2. UC Davis Integrated Pest Management

3. Olive Fruit Fly F. G. Zalom, Entomology UC Davis

4. L. Ferguson PhD Pomology, UC Davis

5. California Olive Oil Counsel

6. Dow Chemical,  Dow AgroSciences LLC GF-120 Naturalyte Fruit Fly Bait

7. Marvin Martin,  Master taster and olive oil expert at