white fluff and blackening of miniature cacti? (2MB of photos)

[Rich]

I have 4 miniature cacti (bought from the markets in Canberra approx 6-9 months ago?) and only one of them seems to be growing successfully.

I'm no expert with plants but I have done a search of these forums for "white spots" and other terms I thought would be of help.

I have attached photos below (sorry for the large size but it's required to show the detail). Relevant photos are below the descriptions...

The one on the left has alot of fluffy-looking white stuff on it but otherwise seems OK. (I'm cactus, alright!)

The next one seems to be turning black at the top and has shrunk in size.

The third one is also going black, but around the side.

The 4th one is the only one that seems to be growing in size without any similar "features" to the others

They have been kept in the kitchen which only gets a little afternoon sun.

http://ww2.datazap.net/ftp/basshead/cactus...us/DSC00022.JPG (photo of them altogether - a tea-spoon is included to indicate relative size)

Perhaps they are being under-watered (I water them maybe once every couple of weeks - if that).

And if anyone knows what kind of cacti these are, I'd love to know

[ 27. May 2005, 08:01: Message edited by: Rich ]

[Benzito]

Unfortunately, I'm no expert either, but if you ask me it sounds like you are probably OVERwatering.

It may well be rot of some sort, due to excess moisture.

it's better to underwater, than overwater a cactus. They will forgive you for underwatering, but not if it gets too wet!

Hope someone else can actually confirm exactly what you're looking at there though.

Best of luck,

Ben

[strangebrew]

To many big pics for my line to handle but they're Mammillaria's.

Have you tried picking off the white-stuff? What's it like? Does it look like it could be small bugs or eggs?

Is it getting worse?

Google 'mealy bug' and compare. They love Mamms to hide in but generally they're attracted to the inner parts. If it is, you've got one hell of an infestation.

Your cacti probably don't get enough sun.

[ 27. May 2005, 13:31: Message edited by: strangebrew ]

[strangebrew]

Ok I waited a bit longer, photo compression is a good thing - try it!

You've got mealy-bug big time,

I'm sorry to say that destroying your plants(except for the last one, this looks OK) is the best and only real option now and the last one will have to be treated.

[Gunter]

The best option sadly, but not the only one.

Systemic insecticide is also an option.

Mealy bug are not very friendly, be mean to them.

[Flip]

Yup, you have mealy bugs

Best to get out a hose and spray as many off as you can

right now.

the dew (read excrement) will spawn fungus and bacteria

and can cause real problems (kill)

spray that off.

You can use a poison or the hose to spray (weekly) to get rid of them.

they're covered with wax so many water based poisons are limited in effect.

Here's an idea

hose spray the cacti as best you can.

wash as many as you can off (turn upside down)

then either dip the plant in 90% rubbing alcohol

or spray your cacti with it when it's dry.

Hehehe - that'll get em'

[ 27. May 2005, 22:28: Message edited by: Flip ]

[Rich]

I didn't think it would be mealy-bugs because of the small size of the cacti, and never actually seen the bugs...

[Flip]

Rich,

I can clearly see them on your oversized picts.

get a magifying glass.

They excrete wax and build up these tufts.

look at this colony (off the above link I gave you pict #46.)

[ 28. May 2005, 02:42: Message edited by: Flip ]

[strangebrew]

Once rot caused by mealies has set in, it's a total waste of time trying to save them. Any with rot, burn or throw out with the garbage.

[Rev]

yup

mealies are the white death

ill prob not ever get that keen on mammilarias simply cos they are such mealy magnets

i use pyrethrins to kill off mine, i do the rounds once a week to inspect (farking ants farm them like scale) but like SB says if its set it its CACTUS

Archaea can you give the active constituets of an effective systemic insecticide please. Id like to keep M craigii and a couple others as specimen and seed plants and i dont think ill do it without these.

[Rich]

Just gave them a dose of Yates "Confidor". Need to reapply in 2 weeks then 2 weeks later again.

Bought some more cactii/succulents (including a little aloe-vera plant) in case my existing ones don't survive...

[amanito]

Just put it of with a tiny thing and wash your cacti. If it comes back you'll have to boil some tobaccaleaves for an hour or something and with that water you can scare away bugs. Be carefull, very poisenous, don't attach the water.

You can also make an extract of mixture of spiritus, green soap and tobacco, even onions, ... etc.

[trucha]

I've heard of friends successfully using beneficial nematodes to get rid of horrible infestations of root mealies in cactus gardens but have no experience with it myself.

[ 05. June 2005, 08:04: Message edited by: trout ]