Scale disaster! Help!!!

I have had a few kratom trees for several years now, I have a large bumblebee that’s about 6 feet tall and 2 green Malay that are about 3.5 and 4.5 feet tall. My bumblebee is great and healthy, it transitions well to the seasonal changes here in Virginia and I never have any problems with it. My Malay’s always seemed a little finicky and would go from super healthy to dropping off most of the leaves in a short time. I finally figured out that the two of them are infested with scale bugs. I have been treating them now for several weeks and they are still alive but the smaller one has no leaves left and the bigger one has very little leaves. I have been rotating between neem oil, Dr.Earth final stop spray, insecticidal soap, rubbing alcohol and have been picking the bugs off by hand. I also replaced the top 1/3 of the soil with new soil. Does anyone have any advice or suggestions I can try? I really want these to survive because I grew them from seeds so I will try anything. Thanks everybody :)

@amhs_monkey you're doing the right things. I use cotton swabs/alcohol to physically remove visible ones. Neen oil spray for the rest. They are hiding in some soil too. I'd replace top few inches of soil too. Please let us know if we can be of any future help. I'm near Daytona, but happy to advise.

last edited by peteypyro

@peteypyro thanks for the reassurance :) I will try the cotton swabs too, I appreciate your help 

@amhs_monkey try adding some diatomaceous earth to your spray, or just sprinkle it around the soil. Should help with scale and many other pests.