Mealy bugs

[Olivesnephew]

I have had a problem with very resilient mealy bugs for the past few months. My cacti live near to my East facing kitchen window in London, which is the best location for bright light that I can offer them. Last year I increased my collection with some new plants, after rather ignoring my few cacti for several years. But five or six of the new arrivals started to get mealy bugs that didn't want to go away. I started out using SB Plant Invigorator, but that didn't seem to work. So after some online research, I bought a bottle of Neem Oil & I use a few drops of that (once warmed up a little) in some warm water & then sprayed on. This seems to have had some effect, though I gave up on a Mammillaria yesterday & banished it to an outside window ledge, where it will either live or die - there's not much more I can do.

The worst sufferer seems to be a small Astrophytum Capricorne v. Niveum - the darn things keep reappearing! I soak the soil when I spray the plants as I believe the pests can live in the soil as well as on the plant. And yet most of my two dozen or so cacti, all grouped quite closely together, seem to be unaffected.

Am I using the right stuff? Has anyone else in the UK had similar problems? Any comments welcomed.

[greenknight]

Root Mealybugs are a different species than those above ground, the only way to diagnose them is to inspect the roots.

Did you clean up the surrounding area? Mealybug nymphs are tiny, almost invisible, and they crawl around, they can reinfect your plants if you don't get rid of them.

If you use anything that doesn't have residual action, you need to treat repeatedly to kill the new hatchlings - don't wait until you can see them, by then they may have laid more eggs. Hatching occurs within 1 to 3 weeks, so several weekly treatments should be given at least.

I have had success using a soap solution, but you have to be persistent. The surest way to get rid of them is to use a systemic insecticide, these are absorbed by the plant and it remains toxic for quite a while - thus one application does the job. More expensive and more toxic, but undeniably effective.

[CactusMad]

Hi get some provado,that's what i use.

[Olivesnephew]

Root Mealybugs are a different species than those above ground, the only way to diagnose them is to inspect the roots.

Did you clean up the surrounding area? Mealybug nymphs are tiny, almost invisible, and they crawl around, they can reinfect your plants if you don't get rid of them.

If you use anything that doesn't have residual action, you need to treat repeatedly to kill the new hatchlings - don't wait until you can see them, by then they may have laid more eggs. Hatching occurs within 1 to 3 weeks, so several weekly treatments should be given at least.

I have had success using a soap solution, but you have to be persistent. The surest way to get rid of them is to use a systemic insecticide, these are absorbed by the plant and it remains toxic for quite a while - thus one application does the job. More expensive and more toxic, but undeniably effective.

There are what I assume must be mealybugs on the surface of the plant. They're easily squashed with a toothpick when visible on the surface of the plant.

No I haven't examined the roots, unpotting a cactus in the middle of winter didn't seem like a good idea. Isn't Neem Oil supposed to have residual action?

[Olivesnephew]

Hi get some provado,that's what i use.

Never heard of that, I didn't came across it when I researched this online a few months ago, Neem Oil was the thing that most people seemed to recommend.

I googled Provado & found that Amazon would sell me a bottle for £11.26. The worst affected plant cost me £2!!!

[CactusMad]

I get mine in a 1 litre spray bottle for £5 99 at my local garden centre.

Just found out that some homebases are selling these 1 litre bottles for £1.43 and the 400ml bottles for just £2.43.Typically they have all sold out near me,worth a check.

Also at Wilkos it is only £3.75 for 1 litre spray bottle.

[7george]

No I haven't examined the roots, unpotting a cactus in the middle of winter didn't seem like a good idea.

That is the best time for unpotting or repotting of cacti. During the growing season this would disrupt growth for some time.

Unless your cacti are buried under snow, are they?

[Olivesnephew]

No I haven't examined the roots, unpotting a cactus in the middle of winter didn't seem like a good idea.

That is the best time for unpotting or repotting of cacti. During the growing season this would disrupt growth for some time.

Unless your cacti are buried under snow, are they?

It's not even snowing outside, never mind in the kitchen where my cacti are!

I always understood that cacti should be left undisturbed in the winter, & that repotting & then watering could give them an unwanted boost during their dormant season. So I have always repotted mine in the Spring. Have I been doing it wrong all these years?

[greenknight]

Don't water right after repotting, give time for injured roots to heal - a couple weeks or more.

[Olivesnephew]

Don't water right after repotting, give time for injured roots to heal - a couple weeks or more.

I'm struggling here. I don't want to sound ungrateful for the advice, but it's difficult to know what to do when someone advises you to do something that's contrary to what I was taught, & what I have done for the last three decades or so. I always give a plant a decent soak in lukewarm water after repotting - gives the soil a chance to settle in around the root ball, & gives the plant a drink to get it over any shock. As for injured roots, surely we all try to avoid this.

I'm confused about what to do now!

[greenknight]

Non-succulent plants need that, they depend on the roots constantly taking up water to replace what they lose by transpiration - they soon wilt without that. Cacti and other succulents are adapted to survive periods with no moisture by storing water in their tissues - they can be left dry for quite a long time without harm, they can even be left bare root. For that matter, they can survive for a long time with no roots at all!

It's impossible to completely avoid doing damage to the roots when you unpot a plant, and cacti are prone to root rot, so it's just safer to wait a while before watering. You can usually get away with watering immediately - I did it that way for years. Now I just jog the pot to settle the soil a bit and wait on the watering. The medium will tend to settle more when it's finally watered, I then top it up and add rock mulch at that time.

[iann]

Never heard of that, I didn't came across it when I researched this online a few months ago, Neem Oil was the thing that most people seemed to recommend.

"Most people" are idiots Provado is the most widely used systemic insecticide in the world, available from all good garden stores. And B&Q! It is one of only two left on sale in the UK, although either should be equally effective against mealies. Bug Clear Ultra is the other one. Read carefully, they have a terrible habit of selling several different entirely different insecticides in almost identical packaging. You want the one with Acetamiprid in.

You can get ready-mixed sprays for a small number of plants, but if you have something that might be called a collection, it is more effective to get the concentrate. The Vine Weevil product is labelled for use as a soil drench, although it is exactly the same active ingredient as the spray mix.

[Olivesnephew]

Thanks everyone. I think the mealy bugs have gone away, fingers crossed. So maybe the Neem Oil does work? If the little b*****s do come back, I'll give Provado a try.

Repotted what needed repotting a few days ago, & found that I've lost a Parodia (bought last year) to rot over the winter. I don't see to have much luck with Parodias.