So I just got a new mini greenhouse indoors and all my plants have been happily living in it under a grow light.
This evening I returned from work to find my Gymnocalycium quehlianum (like a cactus) had some white powder substance under the thorns / spikes. Initially I thought it is probably limescale sedimentation or minerals excreted through the plant pores (like jade plants do).
But now I suspect mealy bugs.
Can someone please help identify and let me know what should I do? Can I use the 99% isopropyl alcohol used to clean electronics on it?
Appreciate your help please I do not want it to spread and kill all my plants. I have isolated it into a dark corner of my cloakroom for now.
Your photos aren't quite clear enough to make out individual critters but from the look of it I would suspect Mealybug the Isopropyl Alcohol you have will do the trick (Methylated Spirits is an old favourite) make sure you dip a cotton bud in the alcohol and then carefully dab each Mealybug you can see the fluff should melt away and then you will clearly see the Mealybug go a shiny grey colour as they absorb the alcohol, be careful not to touch your plant too much with the alcohol though.
I would check all your other plants for Mealybug at the same time and make sure you check under pot rims and in drainage holes I would also empty your mini greenhouse and spray and wash the insides as well as underneath the plastic struts and behind the poles which fit against the plastic covering
Thanks a lot for your reply Carl.
Do I need to change the soil too? I guess I might as well to be careful.
No other plants seem to have any residue of a similar manner on them so I am unsure if I should just wipe all the plants with alcohol anyway to keep them safe?
FaeLLe wrote:Thanks a lot for your reply Carl.
Do I need to change the soil too? I guess I might as well to be careful.
No other plants seem to have any residue of a similar manner on them so I am unsure if I should just wipe all the plants with alcohol anyway to keep them safe?
What if spray the whole thing with alcohol?
You could pop it out to inspect the root ball and make sure there isn't anything lurking down there but, and I cannot stress this enough, do not spray or wipe your plant with alcohol
I use a small artist's paintbrush with a fine point on it. this allows me to put the meths or whatever exactly onto the mealy bug.
For a large number of mealies I have used one of the small hand sprayers with a mixture of water and meths (about 2 parts to 1 part). I spray the plant all over and then place it in a shady position for the alcohol to evaporate. You need to do this in a well ventilated area, otherwise you can inhale the alcohol, which can make you light-headed quite quickly!
P.S. Love to see you at a Dartford branch meeting.
I use a small artist's paintbrush with a fine point on it. this allows me to put the meths or whatever exactly onto the mealy bug.
For a large number of mealies I have used one of the small hand sprayers with a mixture of water and meths (about 2 parts to 1 part). I spray the plant all over and then place it in a shady position for the alcohol to evaporate. You need to do this in a well ventilated area, otherwise you can inhale the alcohol, which can make you light-headed quite quickly!
P.S. Love to see you at a Dartford branch meeting.
Thanks folks I did just that but I could not risk any further infection so I took really drastic measures. Took it out of the pot and took off most of the root system (it actually crumbled and broke off when trying to remove the dry soil) and drenched the whole thing in isopropyl alcohol.
Put some mycorrhizal fungi around the roots and potted it in my usual gritty mix. I also sprayed alcohol all around and wiped down the top half of the greenhouse where it is and hope no further infection spreads.
Some people say to spray twice a year with dimethoate based insecticide, any comments on that?
cactuspip I have been slacking from joining the 2016 meetings because I got caught up in work related travel. Will do my best to attend my first meeting in the next one on 23rd
Less than 12 hours after spraying the whole thing with 99% isopropyl alcohol and removing all the roots, spray drenching roots with alcohol and repotting it there are some white specks on some of the spines again.
Does anyone think that this could just be mineral deposits that the plant is leeching out through its pores?
Maybe it is not a mealy bug attack after all... I just cannot see anything moving even though my eyesight is perfect!
Maybe you killed them but the wool and dead bugs still remain and are showing up as the alcohol evaporates? I usually blast them off with water to get rid of the "cotton". You could rub them off the spines with a cotton bud or artists paint brush soaked in a little soapy water. In fact just a soapy water spray will kill mealies.
Personally I just use one of the Bug Gun type insecticide sprayers for spot treatment available from most DIY stores with a garden department, or Garden Centres.
Alcohol won't reliably kill eggs, which you certainly have if the infestation has got to the stage of adult females being wrapped up in wool. When the eggs hatch they will be tiny nymphs that are the most mobile stage. Some species give birth to live nymphs, but you can't guarantee to have got them all, since they are quite well protected inside their nests. I wouldn't panic after 24 hours, but in a week or two you will almost certainly need to spray again. The lifecycle is relatively slow, typically several weeks from birth to maturity, but this varies with temperature. So long as you aren't damaging the plants, you can use your alcohol spray every 1-2 weeks until you are sure there are none left. Also keep a close eye on other plants since the nymphs will spread quickly.
I do the same as Dave. I take them outside and blast them with water as once the live bugs and eggs are off they are off. I have found it much more effective so I don't bother with insecticide or alcohol if I have the time to do this.
Maintain National collections of Copiapoa, Matucana and Turbinicarpus for Chester Zoo
Personal favorites Ferocactus, Astrophytums or anything with a purple or pink colour.
