Read the instructions and FOLLOW them. Don't start winging it with pesticides!

If it says to use a specific spreader-sticker and gives the lab name of the chemical or the brand name or names, use them.

Most organic soaps are "cationic" and herbidical and will cause leaf damage. You need a "nonionic surfactant"

Agree. If a sticker is needed (which it isn't with Thuricide) then one will be included or directions given for which to use. Also check your application rate and method. A light misting of the leaves is all that is needed. They don't need to be drenched to the point that it rolls off. There is a big difference between what you see with your eyes and what is actually remaining on the leaf surface.

Dave

With many spray-on pesticides and herbicides, it helps to lower the water surface tension, to help the moisture stick. Adding a bit of detergent can do that. But Thuricide is a bacteria, and I'd be loathe to add anything to bacteria that might hurt them. But I agree that misting, rather than drenching, is the right approach.

Thuricide is toxic crystal from the Bt bacteria.

And, as others have said, follow the label directions.

thank you for the advice , I never knew organic soap was toxic to plants, I've used murphys oil soap and baby shampoo mixed with copper in small amounts didn't have a problem. is there a better alternative, a lot of times I use molasses as a sticker but more for foiliar feeding. as far as spraying a mist that's kind of hard on a very tall pear trea. maybe all seasons oil would be better?

Organic soap can be toxic, even to people, if you swallow enough of it. Where do we come up with the idea that "organic" stuff can't be toxic? I can name oodles of plants that are highly toxic to humans and you betcha, they're completely "organic".

Thuricide is live bacteria, and they produce a compound that is toxic to caterpillars.

Foliar spraying of just about anything can damage plants when mixed improperly, applied improperly (no drench, no direct sun, no high heat temps, etc.), or used too frequently.

Leaves are living things that need to be able to breathe (exchange CO2 for O2) and photosynthesize sunlight to live. Heavily coat them in anything that occludes the leaf stoma and pores and they begin to die. Heavily coat them in a waxy or sticky substance like a sticker of some kind and airborne fungi more easily attach to the surface and it is more difficult for rain or watering to rinse them off. And mixing multiple components, trying to make a one-thing-cures-all spray usually only complicates the process even more.

So it isn't so much the individual components one uses but the mixing and the methods of application that cause the problems.

"I've used murphys oil soap and baby shampoo mixed with copper in small amounts".

For what purpose? The soaps are normally used for insect control and should be applied directly to the insect pest, not the plant as a whole. Copper is a fungicide that is normally mixed in specific proportions with no sticker, and misted on the plant. It has potentially toxic results when used inappropriately. If you have had no problems then you have been fortunate.

"a mist that's kind of hard on a very tall pear trea. maybe all seasons oil would be better?"

All season oils are also supposed to be misted not drenched for the reasons mentioned above. Sounds like you need better equipment for application. Downwind drift can be quite helpful with spraying and they make special equipment for spraying trees.

Dave