Since a while this fungus infected all my dragon fruit cactus and now spreading to my other cactuses.
Please help if you know what kind of fungus is this,
what is the first cause,
and what is the remedy.

Thank you

Hello!

It would be really helpful if you could put up some pictures of the fungus and your cactus that are affected by it (:

Hope we could help!

Here is some pictures

@motaarji

I don't think you have a fungus problem but an insect problem

It looks like spider mites and scale to me but I could be wrong!

I would wait for others to reply since i'm still pretty new to keeping cactuses/succulents myself.

I don't think its the same problem on all of them. Some look like powdery mildew fungus (pic 1) and others could be cultural.(pic 2)

Hi, My brother also have cactus that have similar problems, is this due to fungus or mites, and can somebody teach us how to treat this issue? Thanks alot..








Another one

And one of my own cactus also started to have the same problems, in fact this cactus is the same batch / purchase with the previous one, please help... tx.

Doesn't seem to look like fungus.

My general rule of thumb is that if it cannot be removed with deliberate action of a toothpick (or other small pointy tool), then it is not an insect. As for the fungal realm, I almost never experience problems there because my plants get lots of light and lots of air flow. Those are your antidotes for fungal problems, to the extent they are within reach. Strong light and continual air flow are your cacti's friends. There are (at least) two other possibilities to consider: scarring from some previous attack, or spider mites. I have no experience with spider mites (they hate humidity, and our average humidity here is 70-80%). Mite control is distinct from insect control and requires different chemical agents.

When in doubt, the easiest and least harmful treatment for any cactus malady of this type is 70% alcohol from a spray bottle, in fine spray. It will pretty reliably kill insects as long as it contacts them directly. Do this right around sundown, to avoid direct sun on the treated parts, and to allow the alcohol to persist in liquid form for as long as possible.

Most cacti (and many succulents) are covered with a waxy layer that makes them extremely resistant to the deleterious effects of alcohol, so you don't need to worry about harming the plant, providing you aren't dumping industrial quantities of alcohol on there.

If the alcohol does not work, move on to step B: mite or fungus control.

Antifungal agents fall into (at least) 2 general categories: topical treatments and systemic fungicides. I would recommend considering both alternatives if you have ruled out insects as a causative agent, and are unable to find the characteristic signs of mites. Many antifungal agents describe themselves as most effective (if you read the fine print on the instructions) as preventive agents, ie. something you apply to the plant every 7-10 days (assuming it doesn't rain) before the situation gets out of control. In theory the systemics (azole fungicides, generally) confer upon the plant some kind of inherent immunity to fungal attack, once they have been taken up and transported by the plant. Finally, it is generally recommended to not rely on one agent alone for control, rather alternate between 2 or 3 different ones, so the fungi (smart little eukaryotic bastards) don't acquire resistance.

Thanks to all for the information, I have applied some organic pesticide which also claimed as super duper powerful agents than can protect the plant from everything, from insects to fungus. Let's see how it goes. The pesticide smells like rotten egg, if it can not kill the bugs, hope the smell will keep the bugs away. But I really hope that it is just a normal cacti corking process, tx.