Complete newbie so please be gentle:-) I have looked back at previous topics but haven't found anything relevant to this problem.
I have 2 cacti with white 'fluff' on them. Different types and all others seem ok currently. Can you please advise on what this is and how to treat it.

Thanks

Keith

Mealybugs. Clean them with high pressure water and add insecticide.

A truly horrific case of mealy bugs. Spray thoroughly with Insecticidal Soap or alcohol, blast the dead bugs off with your sink sprayer and wait for next onslaught - it could occur in a matter of hours. You can use a toothpick to work the bodies out of the spines. You may have to spray a lot to get them under control. Find a systemic (Bonide granules work well) and use it.

Thanks for the advice. I think I'll just get rid of the plant. I have one other with a far less severe attack which I will try to save. I've had all the plants for several years and never had a problem before. Do particular environments encourage mealy bugs more than others?

I've managed to find a spray which claims it helps to reduce the incidence of mealy bugs. I've move the cactus outside away from all the others and have given it a good blast. I'll repeat the process every few days and await the outcome.

I would definitely toss that. If you'd caught it early or if it was a particularly favourite plant you could maybe try treating it but it looks too far gone to me.

Looking at it more closely after zapping it, parts of it seem to be rotting anyway. It's probably my least favourite cactus anyway it's probably bound for the bin. I'll keep it isolated for a little while just to see what effect the spray does have.

The problem with pesticides and treating insects that reproduce quickly is they (the bugs) build up resistance quickly and the pesticide is no longer effective. That's why new, stronger pesticides are constantly needed. My entire bug spray arsenal consists of Insecticidal Soap and alcohol - because of the way they work to kill a bug (softening their shells so instant dehydration and death), the bugs never build up resistance.

The only problem with I.S. and alcohol is there is no affect on insects with hard shells like beetles. But, as my whole bug problem is mealybugs or scale (the outside bugs have free range ), Insecticidal Soap and alcohol work. The hard scale insects are easy to wipe off with alcohol wipes and Q-tips and Bonide granules work well to keep them in check.

Yes, I would have tossed it but, I don't like suggesting that as people get very defensive when you suggest purposely murdering their 'children'. I have tossed quite a few.

Daisy, you do realize that the Bonide granules you recommend are a pesticide? Namely imidacloprid, 0.22%.

Insects do not reproduce fast enough to build up resistance to pesticides in your yard. It doesn't happen. They might come in from somewhere else already resistant, but the chances of them building up resistance in your own garden are microscopic. Acquired pesticide resistance happens in a statistical sense, only in a really measurable way if it's used in thousands or millions of gardens.

I prefer insecticidal soap (I think Daisy and I both use the Safer brand) and I promote its use as a less toxic alternative to neonicotinoid pesticides (eg. imidacloprid) which may also harm beneficial insects. The trick is to hit every single bug when you spray the plant, and repeat every few days until they are gone forever. When soap does not work, I use the same pesticide that Daisy recommends (but in a liquid form that I drench the soil with). Because it's a systemic, it has to go into the plant and then be consumed by the bugs for it to have an effect, which takes time, and does not typically work as a treatment on its own. Plants in crisis might not be able to perform the necessary tasks for the systemic to work.

I find soap solves the problem most of the time, and the 1-2 combination of soap and imidacloprid is a total solution almost all the time.

That said, I agree with Sue that the best move is probably to toss the plant. It's really far gone.

Yes, and I cross all my fingers and toes the bugs won't become resistant to the Bonide. All my mealybugs and scale are confined to my greenhouse (they don't survive outside) and I make sure there are no survivors, hopefully Bonide resistant bugs won't happen in my greenhouse in my lifetime.

OK. I give in to your demands to murder my baby.

Oh my, that's a lot of mealys.

I'll add some extra support for the insecticidal soap. I recently had to deal with my first mealybug situation. Any plants that were affected got insecticidal soap treatments, and one got isopropyl alcohol (a tropical). All the soap treated ones were cactuses, and it worked great. No more bugs.

Thanks for all the advice. As I intend to get more cacti I'll make sure I get the insecticidal soap supply in too. As I mentioned in my original post, one other has a very small attack from the mealy bugs so I need to get on top of it before it develops.

I haven't been on the site for a while and have just realised I never gave an update on the fate of the other cactus. It is actually thriving now after being blasted with insecticidal soap, and any bugs I could get at being scraped off with a toothpick.