According to a 1994 USDA document, "Imidacloprid is a systemic and contact insecticide exhibiting low mammalian toxicity, with primary activity on sucking insects...". What precautions, if any, should be taken when dealing with plants that have been treated with imidacloprid? I'm thinking of the case of ornamental plants that are edible and can potentially be consumed. For example, a containerized citrus tree. Are there any concerns with eating either existing or newly formed fruits?
I used this on my crape myrtles this year because I read somewhere in a web article that Imidacloprid will not harm bees that suck on the nectar of the flower. It seems a fine distinction to me that sucking on the leaves kills but the flowers won't, but I tried it anyway. The thing is, I didn't have anywhere near the number of bees around my myrtles this year as in the past. I hope this isn't because I killed them all. That said, there are numerous "systemic" products out there - pesticide and fungicide- that list instructions about how to use them on food crops and trees. This must mean that they are ok to use in principle. The product I used, Bayer Systemic Tree and Shrub control lists apple and pear trees as safe to treat. No citrus trees were on the list. I don't know why. By the way Imidacloprid is the active ingredient in Premise which is what my bug man uses to treat my house against termites.
Thanks for sharing your thoughts. Articles on the web convey some concern over the use of this product, including its negative effect on honey bees as you noted. Have a look at this article: Imidacloprid and Honey Bees. Just to be on the safe side I would never use a systemic on edible plants but I wonder about the plants at the store that are labelled as having been previously treated.
Your site on imidacloprid was very interesting. I surfed around on it for a while but could not find what I was looking for. Perhaps you know this info. It seems like most of the beekeeper complaints had to do with direct exposure to the bees by spraying or runoff. The product I use on my myrtle trees, I pour directly into the soil at the base of the trees. I am careful that there be no runoff. The bees don't eat eat the myrtle leaves or bark so they can't get contaminated by imidacloprid through the sap. Is there imidacloprid in the nectar of the myrtle flowers that gets there systemically? One of the articles on your site said tests found imidacloprid in 21 percent of vegetables. Was the imidacloprid IN the vegetables or ON them? Are WE eating imidacloprid? Bayer says imidacloprid can be used on apple trees. Has anyone ever tested the apples themselves?
Just to clarify, I am in no way affiliated with that site - the link was quoted in this thread in another forum. I cannot really answer your questions as I'm no expert on this product (which explains why I'm posing my question here). However, the information on this page at that site specifically mentions nectar and pollen so I'll direct you there for the answer. Also, a quick search pulled up this document in which it states:
The documents at this site are quite technical but I may be able to glean something from them. Thanks.
If imidacloprid stays in the soil and the plant is supposed to absorb the chemical from the soil via the plant roots then why are subsequent applications necessary? Why not wait for the chemical to break down or at least re-apply proportionally less in subsequent years to maintain a steady amount in the soil?
