The Aliens Among Us

Photo credit: Asian citrus psyllid on a lemon Mike Lewis, CISR, UC Riverside
Photo credit: Asian citrus psyllid on a lemon Mike Lewis, CISR, UC Riverside

The fight to Save the Citrus

By Debra Chase

“The perfect organism. Its structural perfection is matched
only by its hostility…its purity.
A survivor – unclouded by conscience, remorse, or delusions of morality.”
From the 1979 film, Alien

Most scientists today would say that there is no such thing as a perfect organism. There is one pathogen that comes very close though, and it is living on earth. Enjoying the warmer temperatures of many sections of our planet, it has spread from its origin in China to other areas of the world. Arriving in the United States in 1998 it was first detected in Florida in 2005 and it has since spread to all of the southern states. Traveling on its own personal vector it is moving fast. California is desperate to avoid it and Florida is at war with it.

Driven by globalization, climate change and monoculture farming practices, the yellow dragon is spewing its fire over citrus orchards throughout the southern United States. This creature and its vector like the heat. They like it so much they have moved into Florida and over 80 % of the citrus crops have been affected, somewhere around 90,0000 acres of citrus. Arriving in Southern California in 2012 it has just recently been detected as far north as San Jose.

In China, they call it Huanglongbing, the Yellow Dragon Disease. An invasive microbe that originated from Asia and has circled the globe. Heat tolerant, the Yellow Dragon moves along on its own special spaceship, the Asian Citrus Psyllid, Diaphorina citri , an ugly little fly that moves around very quickly. The fly eats the new leaf growth and afterward its dark passenger is injected into the tree. The Yellow Dragon can kill a full grown tree in as little as 5 years. Escaping detection for the first couple of years, it has an opportunity to establish itself within the tree and once established it is impossible to eradicate. This lively little alien pathogen literally sucks the life out of a citrus tree. There is currently no known cure for this disease and no known strains of citrus varieties are immune. Commercial growers are using conventional management practices to control the little fly such as pesticides and antibiotics. In some areas the trees are dug up and burned in a final attempt to kill the Yellow Dragon. Scientists are also working to develop a bio-engineered or GMO version of certain varieties of citrus to combat the disease.

None of these practices aids the organic farmer. She cannot use the highly toxic pesticides or antibiotics and she certainly does not want anything to do with GMO’s but she may have a hero. Biologic control in an even smaller creature, a parasitic wasp, found to be a natural predator of the fly. Tamarixia radiata is about the size of a flea and this tiny creature from Pakistan has a big job ahead of it. Released last year in California by UC Riverside Scientists to help protect the citrus crop from the microbial invader, once established it will seek out, attack, and kill the invader fly, in turn killing the Yellow Dragon. So far, this is the organic citrus grower’s only hope.

We squeeze oranges, slice lemons, wedge limes and section grapefruits at an astonishing rate to the tune of billions of dollars annually in California alone. It is hard; no make that impossible to imagine a world without citrus fruits. If this alien is not eradicated we may end up in just such a world.

While we watch and await the fate of the alien invaders, being ever vigilant of our contributions to climate change and the spread of the disease, this simple beverage will assist in the long term appreciation of your orange, lemon, lime or grapefruit tree by creating a delicious beverage that enhances the natural flavors of the fruit and helps to preserve them.

Make a Citrus Shrub by adding 1 cup of your favorite citrus juice to a saucepan, (blood oranges are especially nice in this recipe) and mix it with ¼ cup local honey and ¼ cup organic apple cider vinegar. Bring the mixture to a high simmer, stirring constantly until reduced by 1/3. Remove from the heat allow it to cool and then pour it into your most beautiful quart jar. Stir well and cap it tightly. Leave it on the counter in the kitchen overnight. In the morning shake it gently and refrigerate for a few more days. The lovely citrus shrub is now ready to be mixed with sparkling water for a refreshing beverage.

“In a world where death is the hunter, my friend,
there is no time for regrets or doubts.
There is only time for decisions.” – Carlos Casteneda, Journey to Ixtlan

For more information on this invasive microbe and it’s devastating effects on the US citrus crop contact The California Department of Food and Agriculture .

Debra Chase is a self-taught traditional chef with over three decades of professional experience.  She currently resides in Colusa County on a small farm.  

About The Author

Disclaimer: the views expressed by guest writers are strictly those of the author and may not reflect the views of the Vanguard, its editor, or its editorial board.

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  1. Don Shor

    Thanks for this very timely article. I’ve been seeing misconceptions about this disease problem on citrus in social media. So just to clarify….

    The disease, HLB virus (“citrus greening”) is very destructive. It has wrought havoc in citrus groves in Florida. The only thing that can be done to an infected tree is to uproot it and destroy it.  Juice production in Florida has dropped by about 1/3, with a hit to the state of $4 – 5 billion.

    HLB has been found in California on one tree, an orange tree in Hacienda Heights (in the Los Angeles area) in 2012. That tree was destroyed and the area has been monitored. The disease is only spread by one insect, which we call the vector: the Asian citrus psyllid. It’s a pretty strong flyer, but the most common means of dissemination of the vector is by people moving plants or fruit that are infested.

    There are other plants than citrus that host the psyllid. So the California Department of Food and Agriculture manages a quarantine on the movement of certain plants out of areas known to be infested. The USDA routinely intercepts host plant materials being sent in to California from out of state and out of the country.

    DO NOT bring citrus trees, leaves, branches, flowers, or fruit from a quarantine area. That includes much of Southern California and certain counties in Central California. The nearest finds of the Asian citrus psyllid are Lodi and Manteca, where one psyllid was found in each location.

    Presently there are four main parts to the strategy for managing this disease. Quarantines on the movement of host plants. Insecticides to control the pest.  Research and development of trees that are resistant to the disease. And biological control of the vector via introduction of beneficial natural enemies.

    Quarantines are enforced on nurseries, growers and homeowners by the state Agriculture Department and/or the USDA, enforced by the county agricultural commissioner. They do have broad powers to manage pests on trees in your yard. Shipments of citrus trees that come from quarantine areas are inspected at the grower’s yard and at the retail nursery before they are put out for sale. Quarantines can work, though they impose costs on the industry and are not foolproof. Nurseries are very cooperative, because CDFA and the USDA can shut them (us) down if we aren’t. The most common issue is people who don’t know about them or don’t take them seriously.

    The insecticides used by commercial growers are neonicotinoids, including imidacloprid, on younger trees, and foliar applications of various insecticides on older trees. The first groups of pesticides are systemics that go into the plant and kill the pest while it feeds on the tree. One application a year is usually sufficient for control. Organic growers have to use sprays that kill the insect by contact or by smothering them, so they have to do repeated applications through the season.

    Genetic engineering is being used to create varieties of citrus that are resistant to HLB. Virologists have found genes in spinach that they have transferred into citrus, and the first trees from that were being field tested in Florida as of 2011. They are not immune, so this is not a panacea, and it takes a long time to get from research to field test to propagation, production, and yield. Any genetic solution is several years away.

    The parasitic wasps that are being released are from Pakistan and show good promise for suppressing the population of psyllids to manageable levels. With biocontrol, you never really know what the field results are going to be: whether the new insect will establish, overwinter, and whether it will be sufficient to reduce damage from the pest to economically-acceptable levels.

    For more on the subject, and information about some of the other areas of research underway, here is a great article from a recent article in National Geographic:

    And here is some info from the USDA:

  2. TrueBlueDevil

    Hopefully we can stop the spread. Thank you for the article.

    I watched a TV special a year or so ago about the spread of other invasive critters – Wild Boar, Pythons, and some kind of giant rodent in southern Florida. These invasive species are moving northward, they don’t seem to have natural enemies, and I didn’t get the impression that we were really giving a vigorous effort to eradicate them.

    It seems like Florida is a natural gateway, and these animals and plants are evolving. Some scientists thought the pythons or others wouldn’t move north past a certain parallel because of temperatures, etc., but they have moved past these markers.

    It seems like Florida should be our “beachhead” for many of these invasive species, because if they get up through the panhandle and into the southern US, they could cause tremendous and irreparable damage.

    We could put a bounty on these boars and pythons, enlist prisoners in the effort, do any number of actions to stop the flow. It may be impossible to completely eradicate the python, but I would think we could really slow it down.

    Unfortunately, a look at Wikipedia shows that there are numerous invasive plants, fish, and animals in Florida.


    1. Miwok

      Since no one seems to like hunters any more, maybe we can merely term them as invasive species warriors?

      When I watched the “Saving the Bay” show a while back, they claimed cows and most of the grass in California are invasive species. If they had not done this we would all be eating low-cholesterol elk or deer?

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