Insecticide
 

Does anyone know if Merit 75 WP is safe for use on orchids? The active ingredient is imidacloprid 75%. The label says the application rate for foliage plants is one tsp. per 10 gal. of water.

I use the granular Merit on any of my orchids that have come to me with scale. I know of someone who has used the liquid concentrated form so it may have been the same as what you refer to. It's supposedly more concentrated than the granular form, but I don't have the details on mine.

Some of our society members say is that dendrobiums do not like Merit.

Many people have used imidacloprid on orchids; I've been using the dosage listed at this site: North Jersey Orchid Society

The prevailing wisdom is, if the label says it's good for roses, it's good for orchids.

I Agree with Orchid126. However, if you are paranoid, you can test it out on a single orchid at first.. a test orchid I should say

In addition to roses, if it says it's safe for "Ornamental" plants, then it is also safe for orchids (I included this, b/c sometimes even if it's safe for orchids, it doesn't always mention roses, it will only say "ornamentals" - which includes roses)

Imidacloprid + Clothianidin
 

Several friends and orchid enthusiasts I know swear by a product they use on their orchids. Its brand name is 'Bayer Advanced Tree & Shrub.'

This product contains 0.74% Imidacloprid and 0.37% Clothianidin.

It is applied to the roots, not sprayed on the leaves. When the roots absorb it, it spreads through the plant, providing systemic protection. Anything that tries to eat or suck juices from the plant dies.

I have now tried it myself and can see no ill effects on the test plants.

Application is really easy - you just mix it up in a bucket, then dunk the plants right up to the top edge of the pot. Let them drain a bit and then back to their normal environment.

Alternatively, you can use a sprayer, just spraying the roots - either on a mounted plant or down into the medium of a potted one.

So far, I have only used it on plants that show some obvious infestation or ones that in the past have proven to be 'scale magnets.'

The infestations are gone, and the scale-prone plants show no new bugs.

The guy who first told me about this says he has used it for years with no problem. However, I make no claims (disclaimer) and caution you to try it on test plants first to see if it will be suitable for your specific growing conditions (all my plants are outside all year long in a lath house, coastal Southern California, Zone 10B).

Hope this helps!

I have used Merit...one teaspoon of powder mixed in a gallon of water. I believe that I sprayed the foliage. I guess that one COULD just dip the plant up to the top of the pot, as it is supposed to be systemic...Anyway it did work. Now-a-days, I use the 409-alcohol-water spray three weeks in a row. That works just as well & isn't toxic.....BettyE

Thanks to everyone for the information. Since I have a large number of plants, I think I will use my respirator and protective clothing and spray the entire greenhouse tomorrow. I only have about a dozen dendrobiums so I will relocate all of them before spraying just to be one the safe side.