Question
Hi Will, I seem to have a few problems going on at the same time and I am having trouble dealing with them. I guess it would be best to start at the beginning so you can get the whole picture. It started when about half of my plants (I have about 60 houseplants) got Spotted Spider Mites. I don't know where the mites came from since none of my plants have had them for quite a while (I check all my plants regularly with a magnifying glass) and all new plants get sprayed immediately and quarantined for a few weeks. I sprayed all the plants that had mites with Safer insecticidal soap. A week or two later I started seeing mold growing on the top of the soil of all the plants that had had the spider mites. I took off the mold and the top inch of soil. Within a week, the mold started showing up on the soil of all the plants in that room and then on the soil of all of my plants in every room of the house. Only 2 of my plants did not get mold (both were small China Doll plants that I had propagated several months ago, sadly, the parent China Doll plant that I had taken the 2 cuttings from was the first to die as a result of the problems I am writing about). I removed the mold and top 1-2 inches of soil on all of them except a few that needed to be repotted. The mold finally has gone away, with the exception of 3 plants in a back bedroom, but now I have 2 other problems. In the plants that first got the mold problem (and the first to get the spider mites) I have started finding root rot, it is spreading (I think) through my plants like a plague, following the same pattern as the mold and spider mites. I have also been finding small insects in the soil of some of my plants, there are 2 kinds of them together in the pots, some of them are sort of pear shaped, amber colored insects and the others are the same except smaller and white, possibly a younger stage of the amber colored ones? What are these insects? Could they possibly be root Aphids? As I have been going through my plants checking for root rot, I have found some that have most symptoms of root rot like roots that break off easily leaving the root hair behind but the roots do not look dark or mushy. Some of them I would say, by looking at them, were healthy roots except that they are breaking easily or just falling off leaving the root hairs behind. Most of the roots affected by this and the root rot are feeder roots with just a few main roots affected. Almost all of the plants that have roots like that I have also found those insects in the soil. Could those roots be damaged by the insects and not have root rot? Also, what can I do to stop the spread of the root rot? The plants that have these problems so far are all in the same room, I don't want it to spread to my plants in the other rooms like the mold did. I am very careful to clean all tools, scissors, ect... that are used on my plants. I carefully clean all tools and spray them with alcohol between each plant. Could the root rot been caused by the mold problem? What could have caused the mold problem in the first place? For the root rot I have been taking cuttings of the plants whose roots are too far gone (unfortunately all but 2 of my ivies are gone, couldn't even save a cutting) and on the ones that have just a few bad roots I have been cutting off the roots with rot and spraying the healthy roots with a fungicide (Neem extract) and replanting the plant in a fresh pot with fresh soil. To add insult to injury, I have found that the spider mites are back on a couple plants, one poor ivy had root rot, the soil insects and spider mites all at once. I got Bonide systemic houseplant insect control, it contains 2% of Disulfoton, to deal with the spider mites that have come back. Will that also get rid of the soil insects? Any advice you have for dealing with these problems and to try to stop them from spreading to all the rest of my plants would be VERY welcome, as I am about at the end of my rope.
P.S Sorry this post is so long
(Interestingly, those 2 China Doll propagations that did not get any mold on their soil do not have any of the above mentioned problems that all of the plants around them have, no insects, no root rot and no mold. How could these 2 plants escape these problems when they are right in the middle of all the plants that have these problems the worst?)
Thanks for your time
Melina

Answer
Hi Melina,

There is a lot to deal with here. Probably more than space allows, but you can send me follow up questions to my address below, if necessary.

I think that all of these problems may be related.

Spider mites tend to flourish on plants that are stressed and/or unhealthy. Often the mites are few and far between and virtually undetectable until conditions are right for them to reproduce.

Mold comes when spores are in the soil. Soil insects (probably centipedes of some type) also come in contaminated soil. Although the mold and bugs are unrelated, they both suggest that the quality of soil in your plants is poor. If you have added soil to most of your plants, then you better revisit the soil that you are using. In general, a soilless, peat-based potting mix is best.

The root rot can also be caused by poor quality soil that lacks porosity. Such soil stays wet for too long and does not provide adequate air pockets (porosity) for the roots, particularly as it compacts. Of course other things can also cause root rot, including using pots that are too large (the most common of all plantcare mistakes), and watering too frequently.

Soil that stays too moist not only causes root rot, it also creates a good environment for mold to flourish.

When  plant's roots are stressed, the plant will begin to die. This in turn sends signals to pests, which will then start to reproduce at an alarming rate.

So all of your problems are tied together.

My quick suggestions are that you spray all infested plants with a soap solution; that you move plants into the smallest pots possible; and that you replace infested soil with a peat-based potting mix. It is also important that you keep all of your plants on the dry side.

Please let me know if any of this is unclear or if you have any additional questions.

Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: [email protected]

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