This is a quote from a Wikipedia article. We all know to take W with a grain of salt but this seems reasonable.

From http://en.wikipedia.org/wiki/Imidacloprid

Imidacloprid is moderately soluble in water. When it is exposed to sunlight, it breaks down very rapidly (with a half-life of about 3 hours). Imidacloprid is very unstable in high pH water and breaks down rapidly. In acidic water, and in the absence of sunlight, it has a half-life of about 70–110 days, depending on other conditions. In soil under aerobic conditions, imidacloprid is relatively persistent – with a half-life that can be as long as 6 months. It has a low mobility in most soils and generally has an attraction to clay and loam soil particles. It binds very aggressively to organic matter, which can tie it up and make it unavailable to the plants that are being treated. Pure sand soils do not hold imidacloprid well.


Being a novice at citrus caretaking I have overlooked some significant CLM damage in my trees. I got the idea somewhere that twisted and contorted leaves are common and acceptable on new citrus growth, however with the coming spring and me still seeing this damage on almost all my plants I began to research this a bit more. I found a picture on John Panzarella's site that looks like a lot of my malformed leaves. It is mostly on new growth. Here is a link to the article and picture.

http://sites.google.com/site/johnpanza/citrusleafminer

I started with his article looking for the best treatment. I have applied the Bayer tree and shrub with IMID last year and had long ago suspected that it is no longer working.

This was supported by the quote I started this post with. First I applied on a bright sunny day as a granular application. I'm quite sure that I took a couple of hours to treat each tree. By treat I mean apply the dry grains. Again the quote, "When it is exposed to sunlight, it breaks down very rapidly (with a half-life of about 3 hours)". I'm quite sure I damaged the effectiveness severely but that is just the start of it.

AFTER LUNCH and maybe a brief rest I returned to the grove and hand watered it in which took well over an hour. All told some of the granular application may have had four of five hours of full sunlight before it was safely in the soil. This brings up the second point and I quote, "Pure sand soils do not hold imidacloprid well". I am trying to build the fertility of my soil but last year it was predominately sand. Having said all that I am doubtful as to the effectiveness, especially long term, of my application. This application was with the old formula not the new Bayer that has about half of the IMID in it and is approved for fruit bearing citrus.

I am probably six months out from that application which obviously has failed. This brings me to the last quote, "In soil under aerobic conditions, imidacloprid is relatively persistent – with a half-life that can be as long as 6 months." Seems like it shouldn't be working now irregardless of what I did!

OK What are your thoughts on this?

Now I will throw a curve to you. I have plans to establish a TBH (Top Bar Bee Hive) at my location to help with pollinating. Yes we are short on bees here. I have been aware of alleged issues with IMID and bees.

http://en.wikipedia.org/wiki/Imidacloprid_effects_on_bees

I would really like to treat my trees now BUT the spring bloom is upon us and I worry about the effects on the bees. Different studies now show levels of IMID in pollen that may be detrimental to bees. I do not know what levels were applied so I can't draw any relevant conclusions.

This all may be moot for this season since we are looking at 26 tonight and all my blooms will probably be toast!!!

I would appreciate everyone’s thoughts, references and experiences.

Imidacloprid is highly toxic to bees, both in foliar spray form as well as soil drench. Not really an option I would think, if you're planning on beekeeping. Here is the info on various insecticides that includes hazards to bees from the UC IPM web site:

http://www.ipm.ucdavis.edu/PMG/r107302911.html

Essentially correct, Darkman, so you would have to be extremely careful to make sure you do not apply during bloom times. With a soil drench, it can take an extended period of time for Imidacloprid to reach the leaves, so again, you have to be very careful with the timing. And with lemon trees, which bloom almost all the time, it's basically impossible. Here's a more scholarly article for your review:

http://www.institut-fuer-bienenkunde.de/_bienenkunde/images/default/iwasa_mechanism%20for%20the%20differential%20toxicity%20of%20neonicotinoid%20insecticides%20in%20the%20honey%20bee.pdf

And, another interesting article about atypical foraging behavior with sub-lethal exposures to Imidacloprid:
http://www.bijensterfte.nl/sites/default/files/Yang_ea_2008.pdf

And in doing some further searchings, I found this abstract which finds less toxicity than previously suspected:

http://onlinelibrary.wiley.com/doi/10.1002/ps.957/full

I would contact your local land grant college and ask if any of their research entomologists have more current information with the specifics you're after with regard to Imidacloprid application timing, concentrations and foliar vs soil applications. I think there is certainly a link to toxicities with bees, and for me, it's enough not to use Imidacloprid unless I really need to. It really needs to be used with caution and intelligently, and I can't always say that home gardeners are careful nor knowledgeable enough to use it judiciously. Folks on this forum of course, not really included, as most of our forum members are more than just the backyard gardener

"Now I will throw a curve to you. I have plans to establish a TBH (Top Bar Bee Hive) at my location to help with pollinating. Yes we are short on bees here. I have been aware of alleged issues with IMID and bees. "

You will be much better off with full frames and wax foundation. You'll get far fewer drone cells and better combs as they won't build cross combs.

I raised bees for about 10 years and got 15-20 gallons of honey from my one hive in a good year. SE Texas is a very popular place for northern bee keepers as they can overwinter here without feeding, get a crop of honey in early June here and transport the hives back to the mid West for another crop.This was before the current problems with mites. The honey where I live is plentiful from chinese tallow trees but IMHO doesn't taste that good. My interests finally changed and I sold the hive.

I had 2 deep brood supers and 5 smaller height honey supers. A deep super full of honey is about 100 pounds, way too heavy for me.

You are absolutely right if you are looking for Honey production.

There is currently a line of thinking that the "super" bee that we currently use in hives is less able to fend off the mites and they don't do as good as housekeepers. With the TBH you actually encourage a smaller bee and do not worry to much about Honey production. If the bees can spare some I'll get a little. My primary reason for having the bees is to pollinate what I grow. The TBH require very little in the way of management. If I can get a wild swarm that would be fine.

Italy, Germany, Slovenia, France: Ban Bayer's Bee-killing Insecticides

The Italian government banned the use of several neonicotinoid pesticides that are blamed for the deaths of millions of honeybees. The Ministero del Lavoro della Salute e delle Politiche Sociali issued an immediate suspension of the seed treatment products clothianidin, imidacloprid, fipronil and thiamethoxam used in rapeseed oil, sunflowers and sweetcorn. The Italian government will start a monitoring program to further investigate the reasons of recent bee deaths.

Italy followed Germany and Slovenia which banned sales of clothianidin and imidacloprid in May. In France imidacloprid has been banned on sunflowers already since 1999. In 2003 the substance was also banned as a sweetcorn treatment. Bayer´s application for clothianidin was rejected by French authorities.

The two substances are produced by the German company Bayer CropScience and generated *800 million in 2007. Imidacloprid is Bayer´s best-selling insecticide.

In August the German Coalition against Bayer Dangers brought a charge against Werner Wenning, chairman of the Bayer Board of Management, for marketing dangerous pesticides and thereby accepting the mass death of bees all over the world. The charge was introduced in cooperation with German beekeepers who lost thousands of hives after poisoning by the pesticide clothianidin in May this year.

Harro Schultze, attorney of the Coalition against Bayer Dangers said: "The Public Prosecutor needs to clarify which efforts Bayer undertook to prevent a ban of imidacloprid and clothianidin in Germany after sales of both substances were stopped in France. We´re suspecting that Bayer submitted flawed studies to play down the risks of pesticide residues in treated plants".

Neonicotinoid pesticides are systemic chemicals that work their way through the plant and attack the nervous system of any insect it comes into contact with. The substances also get into the pollen and the nectar and can damage beneficial insects such as bees.

The Press Release of the Italian Government: www.ministerosalute.it (top right: "Tutela patrimonio apistico: sospensione cautelativa dei prodotti fitosanitari utilizzati nel trattamento di concia delle sementi")
http://www.indymedia.org.uk/en/regions/world/2010/11/467782.html

Slovenia,
Ban pesticides
http://www.czs.si/novice_podrobno.php?sif_no=1734

Now in Croatia,
Open Letter to Minister of Agriculture, Beekeepers: immediate ban of neonicotinoid-based pesticides!
http://ziviselo.com/clanci/otvoreno-pismo-pcelara-ministru-poljoprivrede-hitno-zabranite-pesticide-na-bazi-neonikotinoida/

Ivica,

The ban in France was done a few years ago and there were still bee kills after the ban but far enough out that the IMID previously applied was not a factor. Also there were areas that did not have bee kills where IMID was used prior to the ban on IMID.

I have no idea where the truth lies. I have no doubt that if you spray a bee with IMID he will die. I also have no doubt that if a plant absorbs the poison and it is distributed throughout the plant a portion of it will be in the pollen. Is it a lethal dose? Is it a debilitating dose?

It all depends on whose study you read.

This would be the third line in my signature if the space was allowed.

Statistics - Opinions that analyst twist to support the insanity of those that pay them.

Hmm, story continues:

April 19, 2012
"Blamed for Bee Collapse, Monsanto Buys Leading Bee Research Firm"
http://www.blacklistednews.com/Blamed_for_Bee_Collapse%2C_Monsanto_Buys_Leading_Bee_Research_Firm_/19039/0/0/0/Y/M.html

April, 2012
"Europe Moves To Block GMO Crops"
http://www.therightperspective.org/2012/04/08/europe-moves-to-block-gmo-crops/

"...
The decree is in the works. It introduces a complete ban on the MON810 strain of maize in Poland," Sawicki told reporters,
adding that pollen of this strain could have a harmful effect on bees.

On March 9, seven European countries
-- Belgium, Britain, Bulgaria, France, Germany, Ireland and Slovakia --
blocked a proposal by the Danish EU presidency to allow the cultivation of genetically-modified plants on the continent.

Seven days after that, France imposed a temporary ban on the MON810 strain.
..."

Millet, Sawicki is Agriculture Minister, politician.

I have only one hive of bees. I've used Imidacloprid in the soil now for two seasons, but applied after the blooms. My bees couldn't be doing any better. When the wind is right in the late afternoon, I spray with spinosad to control miners. That doesn't seem to bother them either.

Anyone know the dosage for soil drench for 3 gallon citrus? I'd like to do it and recycle the water that drains to avoid polluting the storm water.