I've been away for the last two and a half weeks, and upon return I noticed a few of my cacti had developed white fuzzy spots, which were not there before.
In the worst instance, one cactus appears damaged and oozes brown liquid in one spot, as well as something that looks like sweat on the rest of its body.
I watered all of the plants profusely 10 days before leaving (which was roughly 1 month ago), and was sure to remove excess water from the pots. Before this watering, the last time I watered the succulents was 2 months prior.
Almost all of the affected plants are placed in a miniature greenhouse from IKEA. Due to an oversight, I left both top panels closed before leaving, so I assume air circulation was limited.
The plants are in front of a south-facing window, and on sunny days it they can get large amounts of light and warmth, so the lack of air circulation may have affected them negatively.
I read an article saying that the white spots may be caused by mealybugs. It seems treatable but I'd like to understand whether this is actually the cause of my issue and what the best way to treat this instance would be.
My questions are:
- What are these white and brown spots on the succulents?
- Is there something that can be done to eliminate them and heal the plants?
- What is the cause of this issue, how did it spread to so many plants at the same time, and how can I prevent it reoccurring?
EDIT: It seems like this is a very widespread mealybug infestation. I spent today removing as many as possible, but I'm sure there's more. They're on at least 10 of the plants, maybe more. I'm not sure how they've spread so fast and so widely (I hadn't seen any prior to leaving my house 3 weeks ago, though admittedly maybe I hadn't looked carefully enough). Do you have any tips for clearing these entirely?
This is the cactus with white spots and a large brown spot of fluid oozing from one point on its body:
This one has multiple fuzzy spots and some less fuzzy and more defined small white spots:
This one has just one fuzzy spot on one of the tips:
This one has spots all over its body:
In one instance there are spots on the soil:
Two of the cacti outside the greenhouse also have fuzzy white spots. The white spots are new on the one in the first picture, but the one in the second picture has had fuzz at the top for a long time and I'm not sure if it's due to the same causes.