Mealy Bug

[Flyhighmike]

Hi Folks,

I joined the BCSS about 18 months ago, have a nice but small collection and have managed to grow some rather nice looking cactus from seed. Things survived quite well last winter (2019/20) but towards the end of the summer I have noticed an increasing number of mealy bugs. I took action initially by spraying with Bugclear and using a small paitnbrush and some meths to get rid of those that were obvious. I have even tried to drench the soil with Bugclear.

Sadly, the problem has got worse over the winter even though I made sure I kept my greenhouse well aired.

Anyway I am now getting towards drastic measures and throwing the whole lot into the dustbin.

This note is a last act of desperation - some of my cacti are still in quite good condition but the bugs seem unstoppable and I am now thouroughly disheartened.

Any last minute advice would very very much appreciated.

Many thanks

Mike Andrew (52955)

[FredG]

I'd keep treating at the recommended dosage time periods with a systemic. Although it is sometimes tempting, use of a flame thrower is not recommended

All newly acquired plants need to be quarantined and treated before adding to your collection ( not always possible).
Plant passports do not cover mealy bug.

[Tina]

Try ant & crawling insect powder i had some mealie get into one of my batch of seedlings & this worked, its also good if scariad get in your seed baggie

[el48tel]

Get a small liquid spray bottle and spray with meths. Dabble diatomaceous earth around plants and even add to compost. Systemic insecticide.

[Tina]

diatomaceous earth

didn't work for me but this does

[edds]

I've switched to using SB invigorator and this is certainly killing off the ones I can see with regular repeated treatments.

I keep forgetting to get some more ant powder to use too.

[JonNo]

You have my heart felt sympathy, because I know exactly how you feel... Like you, I have a small collection but nevertheless one of which I'm quite proud, yet despite my best efforts my plants keep being plagued by mealy bugs.

It is all the more annoying because my plants are strictly house plants, so where the little blighters keep coming from is a mystery. Or at least it was until someone on here was kind enough to explain to me that, by the time you see an adult mealy on one of your plants, chances are they have laid eggs... So although you can kill the adult, a few days later it will be replaced and then some.

I have tried nearly everything. I use systemic as many times as is allowed per year, and SB Plant Invigorator probably more times than I should. Last year when the annoyance really started to get to me I attacked the problem by re-potting any plant that I had seen a mealy bug on, or had been standing next to a plant I had seen a mealy bug on. I gave it the full treatment, new pots, new compost (obviously), all roots washed clean. And still they came...

So the conclusion I personally have come to is that you just have to accept that you're going to get them. Kill them when you see them and keep watching for the replacements. I can't deny that for me to a degree it has spoiled the pleasure of the hobby, and like you I even considered just binning the lot, but I like them too much for that!

Keep plugging away in the knowledge you're not alone...

[Stuart]

I'd agree 'S.B. Plant Invigorator' will work well against mealy bugs but is only a contact killer so needs fairly regular sprays. It's not easy to find but is on Amazon and at a few garden centres. Taking a plant out of the greenhouse and hitting it with a semi-moderate jet of water will wash most of them off along with the white 'wool' and mess.
Don't give up, they can be dealt with without too much work, it only becomes a problem if they're not dealt with when first spotted.

Stuart

[Cidermanrolls]

I agree, they are a pain. I’m lucky to have a professional spraying licence so I have access to several insecticides that the general public do not. I am currently rotating between four different actives....with these I have pretty much eliminated root mealies and thankfully now only see the odd above surface mealie.
I find, in my collection, the worst issues are on my old Mammillarias where the pesky creatures hide in the old tubercles at the bottom of the plant. However much you spray, you never seem to get to these in one go and the systemic doesn’t get to them as this area is largely inactive. It’s a race between killing them and the wounds they create letting rot in, killing the plants. A few years ago I lost almost half of my older plants during a period when I had little time to tend the collection.
As well as the insecticides, I also keep a trigger spray filled with methylated spirits in the greenhouses. I typically use this on fresh imports (fewer of those post Brexit) or as a spot treatment if I see anything. Some plants do appear to mark with this though. I bought an Echinofossulocactus from a well known ebayer in Birmingham last year and gave it a precautionary spray, after which it marked up quite badly. It will grow out.

[Chris L]

This article in one of our branch newsletters might prove useful.

https://www.manchester.bcss.org.uk/imag ... ER1998.pdf

It is an old article (pp2-5), but covers really well the life cycle of the mealy bug - really in essence several different creatures (or rather one creature that changes its habits).

It is worth reading to understand why things like insecticides don't always work as we would expect them to.

I've found that meths is probably the only thing that will actually kill them and they need dealing with as soon as they are seen.