Ben, this is my experience only and others may have different results...but I have tried several foliar spray(insecticide), I have even used plain old dish soap and water, yet all the ones I've used caused major yellowing leaves and eventually leaf drop. The only thing that has worked for me is the Bayer tree and shrub insecticide for "outdoor Plants". This is not to be used for plants that your have inside your house. I apply this in the soil and try not to water too much for at least 10 days to make sure it gets to the root zone well. When I water for the first 10 days of application, I water only enough so I don't see water run out. After 10 days you water normally...I would bring it out of the rain also for the first 10 days or the stuff will run out and not work...Mine had scales and mites? and after the application, I've had no problems since, I've only applied it once and so far no bugs, that was over a year ago...

For some reason my adenium"s been very picky with foliar spray, that's why I was thrilled when I found this to work very well for me...This also has some fertilizer in it and made my leaves very healthy after a few weeks...no leaf drop at all from using this. IMHO

Here is the link for the Container Bayer...(Outdoor Plants)

Here is a link that might be useful: Bayer Tree and Shrub Protect and Feed(Container and Outdoor Plants)

Well, I know alcohol cannot be used on adeniums, I recently defoliated a plant. I can use it on my orchids without any problem, apparently adeniums are more sensitive.
I have used Sevin dust (as a spray, 1 TBSP per gallong of water) as I have seen some caterpillar damage on some seedlings and that was ok. I will use Sevin regularly, one of the adenium nursery websites noted that Dithane M45 will also defoliate adeniums, so I would stay from it and they recommend Captan. I use Captan on my orchids also.

So far we have Sevin dust for caterpillar and general topical insecticide and captan (as yet untested by me)
As a topical fungicide....

Unusable, alcohol and Dithane M45,

Any other proven chemicals, positive or negative?

Daconil has a good safety record, but I've never used it on Adenium

joescience, i know nothing about chemistry! please is it true what you say about fungicide?

"As with *all* fungicides, be careful not to get it on the soil"

because i thought that fungicide actually has to be imersed on the soil to be effective.

**** again i know nothing about that kind of science so I probably very wrong?

thank you,
nude gardener wishes all the best

Don't worry, no chemistry being done here. Copper soap fungicides are commercial products that rely on the antifungal properties of copper-salts instead of more complicated, synthesized antifungal compounds. They are generally sold as being more ecologically friendly, although if misused, are just as harmful as the others. The real reason I use them is that they are less toxic to plants, beneficial insects, pets, and pretty much everything else I don't want to kill. I use "Safer" brand, which is available at most of the well-stocked nurseries here in Los Angeles. It is also available at Amazon. I know that at least a few other companies sell copper-salt soap too.

The advice about not getting fungicide on the soil probably does need some clarification. If the mold/fungus is only on leaves and stems, than you should only apply the fungicide to leaves and stems. Avoid drenching the whole plant since it wastes fungicide and kills beneficial fungus that live in the soil. If on the other hand, you've got moldy soil, you will naturally have to apply the fungicide to the soil. You would be better off removing as much moldy soil as you can first, and then only applying the fungicide to the remaining root ball, and finally potting it up in fresh, *untreated* soil.

Of course, the previous advice only applies to topical fungicides (foliar sprays) not systemics. Systemic treatments will of course require soaking the soil, since you are actually trying to get the fungicide *inside* the plant through the roots. Honestly, I don't have much experience with systemics. In general though, succulents aren't a great candidate for systemics, since they take up nutrients and minerals so slowly...

joescience,

thank you very much. i can see on your vocabulary that you know a lot. thank you for your explanation.
see i learned something today.

can i use Captan on my Cactus?

I use a copper sulfate fungicide on cut branches (after pruning) or areas of rot that have been cut away. I don't use it in the soil. My adenium soil doesn't stay moist enough to promote things like fungus gnats.