How to prevent center rot?

gosalskJuly 26, 2014

As the summer sets in, I've noticed a fair number of plants -- sometimes large, healthy ones -- have succumbed to the center rot. I'm sure you know what I'm talking about -- fungus eats away at the center of the plant. The leaves, although largely unmolested, just pull away from the top.

I know how to treat it when it's caught in time -- pull the infected leaves, drain the water, and cut away the infected material. But how do I prevent it?

Realistically I can't dump the plants out every couple weeks. Wish I could.

I'm willing to treat the plants regularly with a fungicide, but which one? Nobody every says. How much and how often? Do the fungicides have any adverse effects?

This post was edited by gosalsk on Sat, Jul 26, 14 at 21:46

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Hi everyone.

gosalsk - Firstly, do you have any pictures of the affected plants, and where are they grown?

Secondly, I think it's better to look at prevention rather than treating the problem when it occurs.

What could be causing it? As well as being a fungal infection it could be caused by coming in contact with some sort of chemical.

I have found here that the most common cause is the plant coming in contact with chemicals such as new galvanized products (mesh or pipe) or CCA treated timber (such as used for shadehouse framework) or chemicals leaching from them when they get wet due to watering or rain.

CCA treatment contains copper which is fatal if brom's come in contact with it. Even water dripping off a copper guttering, copper wire or copper nails is sufficient to cause copper poisoning. See:

When looking for the problem, always look up as well as all around and you may find there is a treated roof timber or galvanised pipe right above the affected plant/s.

In these cases the initial treatment is obviously to remove them from the cause and then treat the rot if it isn't too far gone.

To prevent a recurrence, paint the offending products with a good oil based undercoat and a couple of coats of oil based enamel paint.

I've been there and done that as I lost several plants when I first started with brom's and built a shade house frame from unpainted CCA treated pine.

I hope this is of some help.

All the best, Nev.

    Bookmark   July 29, 2014 at 3:18AM
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What plants are being effected? Neo's? Flushing the stagnate water is the best for Neo's. The other cause is poor air circulation. Fungicides are ok your growing conditions are the cause they wont help...

    Bookmark   July 29, 2014 at 9:18AM
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The conditions vary, but they're all outside, most with their pots set in mulch under trees. I'm very sure they're not being exposed to treated lumber or galvanized metal. No copper either. The plants that do succumb to it are spread out and in different areas. It seems to be random.

The death rate isn't that bad, maybe one plant in a hundred every couple months, but I would rather it be zero. I hate to lose big, healthy plants if it's preventable.

I do occasionally spray the plants with liquid fertilizer tank-mixed with insecticide (imidacloprid and bifenthrin). But from experience I know these don't hurt bromeliads.

I know that not all fungicides work on all plants for all diseases. So I'd really like to know which ones are proven safe and effective on bromeliads.

This post was edited by gosalsk on Tue, Jul 29, 14 at 10:15

    Bookmark   July 29, 2014 at 10:06AM
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Hi everyone

gosalsk - As you've ruled out what I suggested previously, and your plants are growing under trees, could I ask what type of trees they are?

I once read on one of the forums that brom's growing beneath She Oak Trees (Allocasuarina verticillataoften) suffered from Crown Rot due to the build up of the fine needle like leaves in the central vase of the plant. It wasn't so much that there were leaves in the vase but due to some sort of toxin given off by the She Oak leaves in particular as they started to rot down.

She Oaks are sometimes confused with Bull Oaks (Casuarina littoralis) with the main difference being the needle like leaves which are much coarser on the Bull Oak than the She Oak.


I don't know if you even grow these trees in your country but I thought it worth mentioning just the same.

Like HDD says, poor air circulation can also cause rot and this is most common in over-crowded collections where plants are growing in shade houses in cramped conditions with insufficient air circulation between plants. I guess the same could apply to garden grown plants as well if they were over crowded, however you say that your plants are spread out, but are there other plants that could be crowding them?

Another thing that just occurred to me is the mulch; when you say "most with their pots set in mulch under trees". How deep is the mulch compared to the mix level in the pot and is the base of the plant in contact with the mulch. We all know that planting brom's too deeply in the potting mix can create problems and the same can occur if the mulch is too high around the plant. Mulches that contact the lower part of any plant are often the starting points for rot so this all needs to be checked also.

All the best, Nev.

    Bookmark   July 29, 2014 at 4:11PM
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If that mulch gets soaked and hot you will have problems. The pots might not every dry out. I use Consan Triple Action 20. Its fungicide/ algaeside. Lowes and Home Depot carry it. It hasmany uses inside and outside.

    Bookmark   July 29, 2014 at 4:22PM
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Thanks, Nev, I really appreciate your suggestions.

My plants are all in terra cotta (clay) pots. Most have an inch or two of the rim sticking out above the mulch. Some of the trees they're under do drop a lot of debris -- Bradford pears have countless little vestigial fruits that rain down on everything and easily lodge in bromeliads. But they don't seem to hurt anything. I haven't noticed the problem is any worse under those trees.

Air circulation is good, too, for the most part. I use heavy pots and set them in the ground because they frequently blow over if I don't!

The rot almost always starts at the top and not the bottom. After I pull the loose tops and dry them out, the decay usually stops and most afflicted plants survive long enough to pup. I have a neo "Pink Tips" with one leaf left that's growing a pup as speak. I have noticed that vrieseas seem to want to rot from the middle. Overall they fare more poorly than neoregelias (moderate rot problems) or billbergias (rare). Aechmeas are a mixed bag but during the summer they seem to be nearly immune to fungus. I have a few guzmania and I can't recall any of them ever rotting like this outside.

HDD: Thanks for the suggestion! Is that the same as Physan 20? I have occasionally used that to control algae. If you use it for fungus prevention, how much do you apply and how often?

    Bookmark   July 30, 2014 at 11:15AM
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I've never had to combat fungus or other rot-causing elements directly, but I am always inclined to try basic organic fixes before going for the big guns. I read from many sources that cinnamon has anti-bacterial/fungal properties, so I've always used it when trying to maintain clean soil for smaller, finicky plants, and seeds. I've never seen mold, mildew, fungus, etc. build up on areas treated with cinnamon. Take this with a grain of salt, speaking purely anecdotal. And you should definitely keep investigating for the root cause of this, treating symptoms rarely works in the long run.

    Bookmark   July 31, 2014 at 1:27AM
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gosalsk in my humble opinion it is much better and safe renviromentally. I discovered it after a hurricane flooded us. It was used to prevent the mold from forming in sheetrock carpet..etc in our homes and experimented it with it from there with zero negative results. Works great in the boat too.

    Bookmark   July 31, 2014 at 10:45AM
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As far as cultural practices go, I'm pretty sure I know what the major cause is -- having the cup full of water all the time. Like I said, I wish I could dry the plants out every couple weeks, but it's just not possible.

naoh123: ironically the fungus that causes this injury seems to be called "Phytophthora cinnamomi" because it was first identified on cinnamon trees. That doesn't necessarily mean cinnamon isn't effective at treating it, but I'm always skeptical of home remedies.

The disease seems to have been studied in pineapples (google it). One recommendation I'm going to try is Aliette WDG. It's expensive (~150 USD for a 5lb bag that doesn't go as far as you might think) but it's worth it to me if it works. I will let ya'll know how it turns out.

Here is a link that might be useful: Study on Aliette and pineapples

This post was edited by gosalsk on Mon, Aug 4, 14 at 11:32

    Bookmark   August 4, 2014 at 10:24AM
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So after about ten days the Aliette (aka Fosetyl Al) hasn't killed any of the plants I sprayed.

It's labeled for foliar application to pineapples, which is the amount I used. I assume it's safe to spray in bromeliad cups as it was also labeled for drenching entire pineapple transplants in it before potting.

    Bookmark   August 15, 2014 at 8:53AM
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A REALLY dumb question here. Are you sure it's not the just old bloomed out plants that are rotting away? I am glad to hear you get pups. Let us know if the problem goes away with the fungicide applications.

    Bookmark   August 17, 2014 at 5:54PM
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Hi everyone.

gosalsk - I'm not sure that you're on the right path laying the blame for the rot on the fact that the plant vase is full of water all of the time.

I have a reasonably large collection and have never yet emptied out a brom vase. I work on the assumption that no one ever empties them out on the plants growing in habitat so why would it be necessary in cultivation.

I can honestly say that since I've been growing brom's (about 15 years now) the only ones I've ever lost to rot were in the early stages when I had CCA treated timber on the roof and the copper leached out of the timber and onto a row of brom's below. Even then I didn't lose them all as quite a few ended up producing pups.

I also know of another grower who lost two plants to rot, and the problem was traced back to a plant he had mounted on a tree branch above them which he had tied on with quite a lot of bare copper wire..... The same thing happened, every time he watered, the water dripped off the copper wire and onto the plants below, but once again, they did eventually produce a couple of pups. It seems that copper in any form doesn't mix with brom's, except of course the tiny amounts in fertilizers as trace elements.

All the best, Nev.

    Bookmark   August 18, 2014 at 12:13AM
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I really do appreciate your input, Nev. Glad to hear this isn't a problem for you.

I recall reading somewhere that the fungus that causes this rot is usually kept in check by another fungus that eats it, but that fungus requires oxygen and can be smothered by too much water. That seems to be consistent with my experience that drying the plant out stops the fungus. My folks have been keeping bromeliads for more than thirty years and they say they've always had occasional problems with rot. Plus, who says they're not rotting in nature too? Disease isn't unknown there.

I have noticed it's worse when the plants are weakened for whatever reason. Newly cut pups are vulnerable and low light seems to do it, as do cold temperatures (for a few varieties.) I think my conditions are pretty good but probably aren't ideal. I am sure there's no copper or treated wood, though.

I just don't think I can realistically improve my growing area--can't cut down my trees and build a shade house, as much as I'd like to. So bring on the chemicals!


I'm sure it's not just older bloomed plants. I do know what you're talking about, but it can usually be prevented by removing the old bloom -- with neoregelias, use some plyers or hemostats to grab it, and twist).

This post was edited by gosalsk on Tue, Aug 19, 14 at 11:15

    Bookmark   August 19, 2014 at 11:09AM
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