Asian Citrus Psyllid Eradication Program Causes Outbreak of Citrus Leafminer

Florida citrus farmers have been blanketing their orchards with pesticides in an attempt to eliminate the Asian Citrus Psyllid, an insect that caries a fatal citrus disease. But the campaign has had unintended consequences, namely the eradication of the natural predators of another citrus pest, the leafminer. According to the USDA Agricultural Research Service,

“The leafminer moth, Phyllocnistis citrella, forms channels as it feeds inside citrus leaves and, as a result, often makes the plant more susceptible to canker disease. Further exacerbating the leafminer problem is the spraying of more insecticide to combat another pest—the Asian citrus psyllid. The insecticide is killing off the leafminers’ natural enemies, allowing the pest to increase in numbers.”

The moral, in my opinion, is the same for both nature and the economy: don’t tinker with complex systems and avoid putting all your eggs in one basket, i.e. crop monocultures. Doing so is asking for “black swans” and catastrophic failure. As Nassim Taleb says, “counter-balance complexity with simplicity.” The race to layer insecticides on top of insecticides and then search for pheromonal solutions is too complex for my taste.

Italy Questions Neonicotinoid Pesticides, California Department of Food and Agriculture Loves Them

Can I report the CDFA as a pest?

Responding to concerns about the safety of nicotine based pesticides, such as imidacloprid, the Italian government, last year, banned them as a seed treatment. According to the Institute of Science in Society, Researchers with the National Institute of Beekeeping in Bologna, Italy discovered that “pollen obtained from seeds dressed with imidacloprid contains significant levels of the insecticide, and suggested that the polluted pollen was one of the main causes of honeybee colony collapse.”[1] Since the Italian government’s ban last year bee colonies have sprung back. In some regions no hives have been lost at all with the exception of citrus groves in Southern Italy where neonicotinoids were sprayed.[2]

Which brings me to the California Department of Food and Agriculture, whose love for the neonicotinoid pesticide imidacloprid I got to experience first hand. Last year our neighborhood was one of the first targeted by the CDFA for treatment in Los Angeles county after the appearance of the dreaded Asian Citrus Psyllid, a carrier of a fatal citrus disease called Huanglongbing (HLB)–see my early post about the psyllid and HLB. During a brief treatment period last fall CDFA agents and their contractors TruGreen attempted to spray every citrus tree with Bayer Crop Science’s version of imidacloprid, brand name Merit. During that spraying in my neighborhood CDFA agents and TruGreen:

1. Entered private property without warrants or permission.

2. Left misleading notices (click on image at right to enlarge) which failed to note that the treatment was voluntary.

3. Acted in an arrogant, condescending and rude manner. They also lied. When I declined treatment and noted that I was particularly concerned about the use of imidacloprid one agent offered what he called, “an alternative.” Upon further questioning he admitted that the “alternative” was a pellet version of imidacloprid–not an alternative at all, just the same insect neurotoxin in another form.

4. Ran out of pesticide. There are so many citrus trees in our neighborhood that the CDFA ran out of their precious imidacloprid tablets. They never returned to finish the job leading me to conclude that the operation was a kind of pesticide theater, a way to both justify their funding and please their friends at Sunkist.

European beekeepers would like to see all neonicotinoids banned for good. I’d like to see the same here. While imidacloprid is probably not hazardous to humans, all the oranges in the world are not worth killing our pollinating insects. And fighting invasive species this way is a losing game. I believe that HLB is inevitable. It’s just like Pierce’s disease in grapes, which is now an unavoidable part of viticulture in Southern California.

To my neighbors: I suggest we organize. Let’s resist CDFA’s attempt to spray more imidacloprid should they come around again. I’ve created a form where you can leave your email address here. I promise not to share the email addresses you provide or to send out spam. The list I create will only be used in the event we need to organize as concerned citizens. Hopefully I’ll never have to send out an email. But let’s not let CDFA treat us in a rude or condescending manner again. The next time CDFA pays a visit they may come with warrants and be even more surly. I’d love it if we had a crowd to greet them.

Nutria Trappin’ by Bike!

I like to keep up on all the “urban homesteading” trends, but bikesnobnyc beat me to this one: nutria (Myocastor coypus) trapping via bike.

“We then returned with our catch and skinned them, prepared the hides for tanning and butchered the carcass and cooked up a bit of the meat. Most folks seemed pleasantly surprised at the “chicken- like” taste of the meat.”

Read more about it at dellerdesigns.blogspot.com, “Maker of Fine Hats for Town and Country Cyclists.”

The Skunk Whisperer

Normally I ignore the business related facebook pleas filling up the Homegrown Evolution in box, but one came today that I had to grant some free publicity. We’ve all heard of horse whisperers and TV’s dog whisperer. You may have even heard of the chicken whisperer. Step aside for the . . . skunk whisperer, a “no-kill, no-trap” pest control company based in Oklahoma which seems to consist of at least two skunk whisperers, each with their own cartoon avatar and territory.

From what I can tell from the Skunk Whisperer’s website, www.totalwildlifecontrol.com, they seem to practice a common sense integrated pest management (IPM) approach to critter control. In other words, work first on eliminating habitat. Studies have shown that if you trap and try to relocate animals such as skunks and raccoons, you’re just making room for a another one to take their place. If you poison them you risk killing predators up the food chain, not to mention pets and humans. And poisoned mammals have a nasty tendency to crawl into a wall to die leaving a stench that lasts for months.

As a chicken owner I’m sensitive to the raccoon menace. Following the IPM approach, just like the Skunk Whisperer, I made sure the chicken coop was well fortified and I got rid of a water feature that was a nightly raccoon attractant. Our Doberman is the icing on the anti-raccoon cake.

It’s easy to see how preventing points of entry into our homes is one important part of fending off critters. Judging from the voluminous photos on the Skunk Whisperer’s facebook page they focus on screening out critter access. The beehive relocation I helped with recently and the one I’m going to do in the spring are both because hives made their way into buildings with gaps in the woodwork. Close up the gaps and you exclude most non Homo sapiens. And can we please stop leaving pet food outside?

Possum whispering and bare handed trappin’.

It turns out that the Skunk Whisperer also uses a technique I just tried. The contractor who did our foundation work left the crawlspace access door open. I’m pretty sure something took up residence down there. If I just closed the access door I risked having a critter die under the house, or possibly killing someone’s cat. Instead, I got a cheap raccoon-sized trap and rigged it up as a one-way door. Critters can exit, but they can’t come back in. It seemed to work–the trap sprung and something either left or tried to get in and couldn’t. Now I can close off the access door and not worry about the scent of death wafting up through the house. Here’s what my skunk trap-out looks like–excuse the bad picture and remember that it’s not a trap as the exit end is always open:

I cut a board to fit around the trap-out and nailed it to the corners of the crawl space opening.

The next step is to get a cartoon of myself and I’ll be making the big money.

Here’s the Skunk Whisperer removing the Pepsi machine raccoons. As he put it, “They’d put money in and a raccoon hand would come out.”

Root Knot Nematodes, Meliodogyne spp.

Root knot nematodes are my current sworn enemy in the garden. They are very frustrating because unless you know what to look for, you may never know you have a problem. Nematodes are microscopic soil dwelling roundworms. There are many different kinds of nematodes and not all are garden pests. However, the root knot nematode is a very annoying pest indeed. Above ground, plants are stunted. Below ground, the little guys are sucking on the plant’s roots and robbing it of nutrients. This weakens the overall root system, starves the plant and allows entry points for fungus and disease. Bad stuff.

I have had plants that mysteriously won’t grow. No amount of fertilizer, water or sunlight seems to make them happy. Then, I pull out the plant and find the tell-tale sign of root knot nematodes- galls on the roots. The roots are stunted and distorted. They look like they are covered in tumors.

According to my California Master Gardener Handbook, plant parasitic nematodes (including the root knot type) can form complexes with pathogenic fungi in the soil. The pathogens and nematodes work together to damage the plant. Susceptible plants are damaged more than would be predicted from each pathogen alone. They are in cahoots! What is a gardener to do?
Nematodes are known to affect many valuable crop plants. There are chemical treatments available, but for a home gardener who wants to be organic, the options are more limited. I read somewhere that adding organic matter can help by encouraging beneficial soil microbes. I tried that. Plants were still stunted. So I bought nematodes to kill the nematodes. They are supposedly beneficial nematodes that prey on root knot nematodes. Of course, you can’t see nematodes so I felt like I could be the Emperor with no clothes. I have no idea whether there was something in the package or not, much less what the invisible material may do in the garden. But I was desperate so I shelled out the money to give it a try. I applied the beneficial nematodes in my garden and at a client’s house. So we have two experimental plots. I’ll let you know how it goes.
Of course, you can always grow plants that are resistant or not affected by parasitic nematodes. I have noticed that new zealand spinach is totally immune. While other plants are stunted and won’t grow, new zealand spinach flourishes. So if all else fails, I’ll always have that.

The End of California Citrus?

As small as an ant, the Asian citrus psylid is big trouble!

When I spotted state agriculture agents on our street I knew something was wrong. It turns out that a specimen of the dreaded Asian citrus psylid showed up in our neighborhood. The Asian citrus psylid is not a problem in itself, but carries an incurable bacterial disease called huanglongbing (HLB). HLB, first reported in Asia in 1919, renders citrus fruit inedible and eventually kills the tree. Parts of Africa, Asia and South America are infected with HLB and in some regions of Brazil the disease is so bad that they’ve given up growing citrus altogether. HLB is in Florida and is adding to a nightmarish collection of other diseases afflicting citrus in the Sunshine State. Now California growers are panicking with the appearance of the psylid.

So far the psylids found in California do not carry HLB. However, according to an article in the Journal of Plant Pathology (pdf), HLB inevitably follows the citrus psylid within a few years. In several ways HLB resembles Pierce’s disease which has killed most of my grape vines and basically made growing table or wine grapes in Southern California impossible without copious pesticide application. Both diseases are bacterial and both are spread by phloem sucking insects. The pesticides used to control the Asian Citrus Psyllid and the Glassy Winged Sharpshooter (the insect that spreads Pierce’s disease) are also the same, and include a ground application of imidacloprid, marketed under the brand name Merit and manufactured by Bayer Environmental Science. State agricultural officials that I spoke with at an informational meeting on Wednesday in Echo Park hope that applications of imidacloprid and pyrethroids will slow the progress of the psylid and, “buy some time”, as they put it, to come up with a strategy to deal with the possible appearance of HLB. California agriculture officials hope that their proactive approach combined with lessons learned from missteps in psylid control in Florida and the rest of the world will slow the progress of the insect and minimize the damage of an emergence of HLB in California.

Compliance with the residential pesticide application program is voluntary. State agriculture officials will knock on the doors of residents in three areas in Los Angeles where the psylid has appeared to ask for permission for a foliar application of pyrethroid and a ground application of imidacloprid to any citrus trees a homeowner might own.

While I understand the gravity of the situation–we really are looking at the possible end of citrus in California if HLB gets a foothold–the use of imidacloprid gives me cause for concern. Imidaclopred is highly toxic to honey bees and has been banned in several European countries for its likely connection to colony collapse disorder. When I told an employee of the Department of Pesticide Regulation at the meeting on Wednesday that people in my neighborhood keep bees he paused and said, “you’ve got a problem.” Another official said to me that our bees (and presumably other pollinators in the neighborhood) will be sacrificed for the greater good of preserving the state’s citrus industry.

As with Pierce’s disease the best long term solution to this problem will be to breed trees resistant to HLB. This is easier said than done as, unlike Pierce’s disease and grapes, no HLB resistant citrus cultivars have been found. It may be that the only way to breed for resistance soon enough to head off the HLB will be through the development of transgenes with antimicrobial properties. This approach is already being funded by the USDA and the citrus industry.

As a backyard gardener and rabble rousing blogger, I could lose a lot of sleep pondering all the thorny questions this crisis brings up. Are there situations where genetic modification is warranted, or do antimicrobial transgenes pose unintended consequences? Will localized applications of imidacloprid kill our pollinators in significant numbers or will strategic applications head off more widespread use later on if nothing is done? What are my responsibilities as a backyard gardener to large scale growers? Do the benefits of international trade outweigh the inevitable appearance of invasive species? Should we close the downtown flower markets and produce distribution warehouses where state entomologists suspect the psylids might have come from?

Rather than try to answer the unanswerable, I’m going back to two of my favorite books books that don’t have anything to do with plants. Nassim Nicholas Taleb’s The Black Swan: The Impact of the Highly Improbable, a meditation on the logical fallacies of economists and Seneca’s Letters from a Stoic have all the strategic wisdom a gardener needs. Seneca would say, do what is in your power to do and don’t worry about what you can’t fix. Taleb would advice always maximizing upside potential while minimizing exposure to the downside. My unsentimental conclusion: don’t try to grow citrus. If I had a mature tree I’d leave it in place and rip it out at the first sign of HLB. Despite the state’s offer to replace any HLB infected tree with a free citrus tree I wouldn’t take them up on the offer. In our case we have three small, immature citrus trees that are already chewed up by citrus leafminers. I’m pondering pulling them up and replacing them with fruit trees unrelated to citrus. This follows our stoic, get tough policy in the garden. Planting a tree entails a considerable investment in time. It can take years to get fruit. Why not plant pomegranate instead and let other people worry about citrus diseases? If a pomegranate disease shows up, rip it up and plant something else. Following this approach will eliminate habitat for the psylid and negate the need for pesticides.

Orange v. Tuna ¿Quien es Más Macho?

The first consideration with any domestic plant or animal should be choosing species with robust immune systems and then following that up with an objective selection process. This is an approach that mimics one of the fundamental laws of evolution: survival of the fittest. True, there is often a trade off between the flavor and yield of a fruit and strength of its natural defenses. Oranges are juicier and easier to peal than the spiny and seed filled fruit of the prickly pear cactus. But the long term odds of having a reliable supply of prickly pear fruit are a lot higher than a steady flow of orange juice. I may get a few spines in my fingers, but it will be the citrus farmers who will be losing sleep. As Seneca says, “If you shape your life according to nature, you will never be poor; if according to people’s opinions, you will never be rich.”

View a video on how to recognize Asian citrus psylids here.

Behold the Glassy Winged Sharpshooter (Homalodisca coagulata)


I finally spotted my first glassy winged sharpshooter (Homalodisca coagulata or GWS for short) sinking its vampire like feeding tube into one of my hops vines. The GWS transmits Pierce’s disease, fatal to many grape varieties including my flame seedless, a gardening frustration I blogged about last week. For your enjoyment I captured a 1/2-inch GWS specimen and scanned it. Note that the GWS was harmed in the process, for which I’m unapologetic.

While there are many varieties of native sharpshooters in California, the GWS is an interloper from the Southeast US and is much more mobile. The native varieties tend to hang out in riparian areas while the GWS enjoys jumping around backyards, citrus groves and vineyards, spreading a host of nasty plant diseases including almond leaf scorch and Citrus Variegated Chlorosis. The GWS is also responsible for spreading oleander leaf scorch. Astonishingly, 20% of home gardens in California contain oleander and 2,000 miles of highways in the state are landscaped with it. The University of California estimates that oleander leaf scorch could cause over $52 million in damage.

Dig the GWS’s built-in hypodermic syringe!

The discovery of a GWS in our yard has solved a mystery that has puzzled us for years. When sitting under the grape vine covering our arbor we’ve often felt little droplets of water, highly unusual in a place where it never rains past April. Turns out it was sharpshooter pee. Sharpshooters feed on the xylem, the water bearing veins of plants. As the xylem contains mostly water, the sharpshooter must process large quantities of material in order to survive. Excess water is puffed out their rear ends, a fascinating thing to see close up. The constant water puffing combined with their fast side to side movements make GWS seem more like machines than insects. Perhaps we could “monetize” this blog by teaming up with Hasbro and Michael Bay to create a line of glassy winged sharpshooter toys, video games and action movies.

Barring a GWS blockbuster we can instead offer our fellow plant and insect geeks an industrial film from the University of California that delves into the GWS in pornographic detail. Nice retro voiceover talent on that video UCTV (one of Mr. Homegrown’s former employers, fyi)!

If you like that video, you’ll also enjoy UCTV’s 90 minute Home Vineyard lecture. I’ll add one point to that talk: if you’ve got GWS, grow muscadine or native grape varieties. Don’t bother with table or wine grapes until the bright folks at UC figure out how to breed Pierce disease resistant vines.

The Squirrel Menace

In our garden squirrels are a serious problem. Their worst offense is grabbing avocados off our tree, taking a few small bites and then dropping them on the ground for our Doberman to finish off. This year only five avocados made it into the kitchen. Today’s New York Times has just about the only effective solution. Anyone for squirrel tacos with guacamole?

“With literally millions of squirrels rampaging throughout England, Scotland and Wales at any given time, squirrels need to be controlled by culls. This means that hunters, gamekeepers, trappers and the Forestry Commission (the British equivalent of forest rangers) provide a regular supply of the meat to British butchers, restaurants, pâté and pasty makers and so forth.

The situation is more than simply a matter of having too many squirrels. In fact, there is a war raging in Squirreltown: invading interlopers (gray squirrels introduced from North America over the past century or more) are crowding out a British icon, the indigenous red squirrel immortalized by Beatrix Potter and cherished by generations since. The grays take over the reds’ habitat, eat voraciously and harbor a virus named squirrel parapox (harmless to humans) that does not harm grays but can devastate reds. (Reports indicate, though, that the reds are developing resistance.)”

Two tangents here:

1. Please note the dapper gamekeeper photographed for the story. Here at Homegrown Evolution we think it’s about time the work clothes with tie look, such as this gamekeeper’s traditional hunting attire, makes a comeback. No more walking around in pajamas!

2. We’ve got another excuse to replay this old video:

Thanks to neighbor Lora Hall for the link to the New York Times story!

Whiteflies

The upside to garden pests and diseases is getting to do a little amateur backyard science. Any excuse to mix up a martini, pull out the microscope and take a close look at things and we’re all over it. This week’s happy hour entomology comes thanks to a infestation of white flies living on the underside of our tree collards.

I believe the specific culprit pictured above is the greenhouse whitefly, Trialeurodes vaporariorum which, despite the name, does not only inhabit greenhouses. Moving the leaf around under the microscope revealed thousands of tiny eggs pictured on the right. These eggs hatch and pass through several stages on the way to the winged adults seen above. At all stages, whiteflies suck sap from the host plant (brassica family members like collards are a favorite) and exude honeydew. Some whitefly species are tended and protected by ants acting like miniature cattle ranchers in return for the sweet, sticky honeydew–yet another remarkable example of symbiosis among nature’s many cycles of interdependence.

Control of our whitefly interlopers was simple: we washed them off with a hose. If we had a huge row of collards we might have had a bigger problem on our hands, but biodiversity in our tiny backyard means that the whiteflys don’t have many other options for feeding. What we could have done better is to have kept a closer eye on our plants. Daily inspection of more sensitive vegetables is always a good idea, but something we’ve been lax about lately. Keeping intensively planted annual vegetable beds close to places of daily activity means being able to stay on top of pest and disease problems. Raised beds we recently installed by the front door are on the path of our early morning amble down to the street to pick up the newspaper. A quick glance is sometimes all that’s need to spot a problem.

Permaculturalist Bill Mollison and David Holmgren suggest conceiving of our living spaces in a series of concentric zones, numbered one through five, with the first zone being our house and kitchen gardens and the outer zones being less cultivated and more wild spaces. Mollison and Holmgren’s zones are easily miniaturized for small urban yards. Trees that don’t need much attention can go towards the back, the chickens a little closer and the vegetables and herbs can benefit from being close at hand.

For additional information on whiteflys see the Colorado State Extension service’s whitefly quick facts.

Bugs Ate My Garden

A letter from one of our readers:

“I just read the article on growing your own food. I have tried this but have had great difficulty with insect damage. I have tried some of the “natural” insecticides but they don’t seem to work very well. Two of the major problems I have are cutworms that snip off seedlings before they can get started, and a plague of small white snails which invade later in summer and devastate everything. I cannot use chemical pesticides due to my wife’s chemical sensitivities (nor would I want to pollute my garden with them). Any suggestions?”

Read the rest of the article at Reality Sandwich