Over 250 growers, packers, and distributors met with representatives from the California Department of Food and Agriculture (CDFA) November 17 to discuss the discovery of Mediterranean fruit flies (Medfly) and Medfly larvae within Fallbrook’s greater agricultural community and the options available to them to save their crops.
Four adult Medflies and 68 larvae were found after a fruit stripping and cutting operation was conducted in the Fallbrook area from October 29 to November 1, causing the county to quarantine a 79 square mile radius around the infestation site.
CDFA crews are working with local growers, packing houses, transporters, farmers’ markets and other related entities to ensure compliance with quarantine regulations.
According to the CDFA, the quarantine will last for three generations of the Medfly life cycle, which would end in July. However, if more Medflies are found within the Fallbrook area, the quarantine will be extended for an additional 60 days.
A separate quarantine of 114 square miles is in place in the Escondido area, and while its boundaries come close to Fallbrook quarantine line, it does not overlap.
A half mile radius around the Medfly find site is considered the “core area” of the quarantine, said Vince Arellano, CDFA senior agricultural biologist. The Fallbrook quarantine is referred to as a “bullseye quarantine,” he said.
“There are three boundaries surrounding the core area,” explained Arellano. “We draw a half mile circle around the fly find, then extend the second diameter three miles out if we find two flies within the same life cycle. The third ring is a four and a half mile quarantine zone, which is where we place the hold.”
For groves that are partially bisected by the quarantine, global positioning system coordinates will be marked in order to clarify which fruit must be quarantined, said Arellano.
The damage caused by Medfly larvae makes fruit unfit for human consumption. In addition, the presence of an established population would cause severe economic impact via restrictions and prohibitions on the export of fresh fruit both domestically and internationally.
Records indicate that the Medfly has infested over 300 cultivated and wild fruits, including apples, apricots, avocados, bell peppers, grapes, grapefruits, guavas, lemons, limes, mangoes, nectarines, oranges, papayas, peaches, pomegranates, tangerines, tomatoes, and walnuts. In California, the combined 2005 gross value of the above hosts was over $9.5 billion.
“Growers must apply bait treatment during the quarantine every seven to 14 days,” said Bob Atkins, San Diego County agricultural commissioner. “We recommend that growers take advantage of the pre-harvest treatment.”
All exotic fruit fly host fruits and vegetables grown inside the quarantine area must be treated if intended for sale or for movement within or outside of the quarantine area. Treatments must be conducted in accordance with the product and pesticide labels and all county, state and federal laws. An officer from the CDFA must monitor all treatments.
One method of eradication of the Medfly is the use of Sterile Insect Technique (SIT). According to the CDFA Web site, SIT has been successful against pests in California, including the Medfly. Bait stations will be set up in area groves to release sterile male Medflies, which will mate with the fertile female flies, causing them to produce sterile eggs.
Aerial release of sterile Medflies is taking place at a rate of 250,000 sterile flies per square mile per week. The current release area is approximately 9.33 square miles.
Medflies are released seven days a week by private aircraft and pilots under contract to the USDA. Releases are made along predetermined flight lines using global positioning system navigation.
Ground applications of organically-approved Spinosad may be applied to all properties within a 200-meter radius of each medfly found within the eradication area. Fruit stripping will also occur on all known larval-infested and adjacent properties.
Spinosad is safe for certified organic growers to use as well, said Arellano.
A post-harvest treatment would require fumigation or cold treatment of the harvest, said Arellano, but the facilities may not be readily available for use. Additionally, in order to have a harvest fumigated, groves must be a quarter mile away from any school, which has been a problem for growers attempting to fumigate in the past.
“We are not going to compromise the quarantine in favor of other growers,” said Arellano. “Sometimes nothing can be done, and I am sorry for that.”
It is essential that growers inform the CDFA of what their plans are for their fruit during the quarantine, said Arellano.
“We need to know what growers do with the fruit, and who is planning to harvest before treatment,” said Arellano. “We will be available seven days a week. We know [growers] work holidays, early mornings and weekends. We want to work with them, but it’s upon growers to give us information and enough lead time to treat.”
“Once the fruit has been treated, it’s good to go,” said Arellano. “We will be monitoring the treatment of the groves, but the expense is upon the growers for the pesticide and treatments.”
Once cleared by the CDFA, growers are given a permit authorizing the movement of the treated commodity for ten consecutive days. The effective date of any permit issued is the day after completion of treatment. If harvest is expected to continue beyond the permit end date, additional applications will be required. Failure to comply with the treatment schedule will result in the fruit or vegetables becoming ineligible for movement.
Agricultural shipments from the quarantine zones are restricted by regulations designed to minimize movement of potentially infested commodities. Residents and people moving through the quarantine zone are urged not to remove fruits and vegetables from the area.
“The only way to get the fruit harvested is to be a part of our compliance agreement,” said Dan Hamon, director of domestic and emergency programs.
For growers considering waiting out the quarantine, Atkins warns that it may not be lifted in time for fruit distribution.
“We don’t know if we have gotten all of the Medflies,” said Atkins. “You are at risk, and holding out until the quarantine is over is a big risk.”
The breeding site “has been hit hard” by the CDFA, said Arellano. “We can only hope that nothing else will show up.”
The quarantine also requires that local residents not move home-grown fruits and vegetables from the property of origin and that fruits and vegetables may only be consumed on site. The CDFA recommends that growers let the fruit drop, or if disposed of, placed in plastic bags and thrown in the trash.
“The landfills are under compliance agreement, and the fruit will be buried under no less than a foot of dirt by a certified landfill,” said Atkins.
For more information on the quarantine, go to http://www.cdfa.ca.gov/PHPPS/PE/InteriorExclusion/current_grower_info.html. For a list of the restricted fruit and quarantine boundaries, go to http://pi.cdfa.ca.gov/pqm/manual/pdf/403.pdf.
To view the quarantine map for the Fallbrook area, go to http://pi.cdfa.ca.gov/pqm/manual/pdf/maps/3406MedFlyFallbrook.pdf.
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