Is this mimosa diseased?

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I'm growing a few mimosa hostilis indoors. A few weeks ago, one of the plants started getting these red spots in the middle of the stem.

The spots seem to eventually form a line, streaking down the stems and now the branches as well.

The lower, older sets of leaves are slowly yellowing before being shed off.

There even appears to be a small lesion near the base of the stalk.

Overall, the plant appears to be stronger than ever, growing nearly an inch in height each day. It also started branching a couple weeks ago as well.

I'm concerned because other mimosas around this age appear more woody before acquiring their red color. I've been reading about fusarium wilt which is a vascular disease that mimosas are especially susceptible to apparently. Some of the symptoms are similar, but I couldn't find any good pictures or a specific enough description to make an amateur diagnosis.

Could anyone with more gardening and/or mimosa experience enlighten me on what I'm seeing here? I think these could all be natural hostilis behaviors on their own but I'd like to be more confident in them.

 

[wearepeople]

I'm afraid I cannot completely help you, but mine did a very similar thing right before they turned woody.

I'm kind of surprised yours are as big as they are without having turned woody at the trunk. If I was forced to guess, I'd say that yours are just turning woody, thus the red streaks.

If the branches that hold the leaves start turning red, you might be in trouble.

I wouldn't worry too much though, they seem like they're in pretty good shape. They'll drop leaves in a fury if they're unhappy.

 

[BundleflowerPower]

I agree. When the stems and branches turn woody they'll shed the single leaves at the base of the stem/branch. When my big one got about 6 feet tall, it shedded all it's leaves but the branch tips, taking on the familiar mimosa/acacia shape. Just keep an eye on them, but I wouldn't worry too much, they look good to me.

Mimosas are super tough. This summer mine were infested with little green inchworm looking caterpillars. They were feasting on the tender young growth. At first I plucked them off, but then I realized that it doesn't matter how much they ate, the trees just grew more branch tips. The one in the huge pot, when I planted in in my yard, I dropped the whole root ball on him, didn't phase him a bit.

Just keep in mind that they don't need much water, they're from semi-arid scrub habitat.

All of mine had stems which were red before they turned wood, check it out:

 

[jamie]

It's normal. Eventually it will get reddish bark.

 

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Awww, wow! You have a gorgeous yard and plants, Bundleflower. Is that p. Viridis you also have potted in the last pic?

Thanks for the explanations and reassurance, guys! I feel much better about them again.

About the new growth being eaten and regrown... Can mimosas be pruned like a cannabis plant to encourage more branching? That's kind of what it sounds like the inchworms were doing.

One of the new leaf growths on my largest was touching the light for a few hours and got scorched, so I clipped it off carefully. That same day, it started to branch. Not sure if it was coincidence or influenced by the scorching/trimming. The untouched one has not begun to branch, though it has been further behind in growth anyway.

 

[wearepeople]

that's not viridis in the picture.

 

[BundleflowerPower]

It's not viritis, I can't think of the name, but it's a common ornamental shrub who's name starts with G which I took a cutting from.
And yes you can top them to encourage branching.

 

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It's been 3 weeks now and a few bottom leaves have completely shed. I'm worried again though because a couple days ago leaves all over are starting to yellow and drop pinnates. Previously it had just been the lower leaves, on the main stem. Now it's getting out of order. If you look closely in the attached pic, you'll see higher leaves are beginning to yellow, even a couple along the branches that are only a few weeks old.

Is this still normal? I haven't given them any nutrients since potting them ~5 months ago, could it be a deficiency?

 

[BundleflowerPower]

Mimosa does a lot of shedding, they constantly she'd older leaves as new ones grow. They look fine to me.

The only thing my potted tree doesn't care for is being moved. The that cold snap came a couple of weeks ago, I drug him into my garage, then into my greenhouse. He did not open his leaves for 2 or three days, then only partially for another few days. Now he's happy again, growing in high gear again.

He has several bear stems from shedding leaves.

 

[BundleflowerPower]

Are you going to put them outdoors when the spring comes?

 

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Okay, steady as she goes then. Thanks!

I haven't moved them at all but I notice they close some even after being handled or when I have to re-fix the light. They'll be twice as old before it's warm enough again to be outside, but I'm definitely looking forward to it. I put them out for an afternoon this past summer but was worried the hot sun was drying / frying them. Might take some adjusting from their stable, indoor climate.

 

[BundleflowerPower]

The sun shouldn't hurt them once they're used to it. I live at latitude 30 with very intense summer sun, they grow happily in full sun here.

 

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Another update. 2 of the 3 are not looking so good. Here are some more pictures of the shedding leaves.

December 10th:

January 18th:

The new leaf shoots are partially blackening too, as if burnt. I first noticed it a month or so ago.

Anyone have an idea what could be wrong? They seem to be struggling. I watered them with a weak fish fertilizer back in the beginning of december to see if it would help with the wilting. Could it be some kind of nutrient burn on the new baby leafs?

My other specimen is much more healthy looking with what I assume to be a normal amount of leaf shedding and no blackening of the young leafs. I also watered it with the same amount of the fertilizer. Here's a pic of them side by side for comparison. The stronger one was actually ~8 inches taller than pictured but I recently took a cutting.

 

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Also, could anyone comment on my cutting? It was my first time taking a clone from a plant! :d

I used a clean razor blade and sliced the top 8 inches off, right above a node that still had mostly green stem. I cut down and away from the node at a 45 degree angle. New growth quickly began on the 3 nodes below the cut on the parent.

I immediately put the cutting in a cup of water. I picked off the bottom leafs of the cutting and shaved off the outside flesh on the bottom 2 inches of the stem. I then wet the stem and swirled it in a rooting horomone, tapping off the excess. I gently placed this in a small pot of soil and am misting it to keep the soil moist.

 

[Continuum]

Oh, that blackening of the new leaves does not look good. I have not had it happen, but a knowledgeable soul says that rot is one thing that can get them at that age. If it were mine, I'd a) let the soil dry out, b) cut all the blackened tips, and c) remove the gravel/mulch? cover on the top of the soil to help with the drying and soil air flow. Might also water with a diluted peroxide solution (1%)for the next few waterings.

Other than that, too little light may be an issue. Mimosas like full sun and don't do as well under lights unless the lights are pretty intense. Mimosas will go into preservation mode in what they consider low light conditions and drop all their leaves that are not close enough to the light source, including those blocked by higher leaves. In your side by side pic with the healthy plant, the shorter of the two is not close enough to the light just by virtue of being the short one. You should put a box or something under the pot so it is up just a few inches below the light source, like the taller one. You want them like 2-3 inches below the light. You should also consider putting some aluminum foil, white cardboard, or other more reflective material on your wood paneled walls to maximize the amount of light getting to the plants.

As for the cutting, mimosas do not root by cuttings very easily. I've tried a bunch with no success. From what I hear, air layering is the best way to propagate via cuttings for these guys, but you will need to get them to the point where they go woody and have some pencil thickness branches. That will happen after one growing season outdoors, probably ready to begin the process on their second season. Your method looks good- it's just the species that's keeping you from having success.

Good luck! Let me know if I can help with anything else.

 

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Oh, that blackening of the new leaves does not look good. I have not had it happen, but a knowledgeable soul says that rot is one thing that can get them at that age. If it were mine, I'd a) let the soil dry out, b) cut all the blackened tips, and c) remove the gravel/mulch? cover on the top of the soil to help with the drying and soil air flow. Might also water with a diluted peroxide solution (1%)for the next few waterings.

Other than that, too little light may be an issue. Mimosas like full sun and don't do as well under lights unless the lights are pretty intense. Mimosas will go into preservation mode in what they consider low light conditions and drop all their leaves that are not close enough to the light source, including those blocked by higher leaves. In your side by side pic with the healthy plant, the shorter of the two is not close enough to the light just by virtue of being the short one. You should put a box or something under the pot so it is up just a few inches below the light source, like the taller one. You want them like 2-3 inches below the light. You should also consider putting some aluminum foil, white cardboard, or other more reflective material on your wood paneled walls to maximize the amount of light getting to the plants.

As for the cutting, mimosas do not root by cuttings very easily. I've tried a bunch with no success. From what I hear, air layering is the best way to propagate via cuttings for these guys, but you will need to get them to the point where they go woody and have some pencil thickness branches. That will happen after one growing season outdoors, probably ready to begin the process on their second season. Your method looks good- it's just the species that's keeping you from having success.

Good luck! Let me know if I can help with anything else.

Thank you for taking the time to review the thread and answer some of my questions! I'll definitely get the weaker ones closer to the light and something against the wood paneling. I've been wondering for a long time what kind of intensity light I need, I guess the fluorescents won't cut it. Which kind of light would you recommend? Metal Halide?

Yea, I think I screwed up with the soil from the start. I initially transplanted them into a mix of 30% composted manure, 40% backyard topsoil, 30% vermiculite. In retrospect, this mix is very heavy compared to some of my other plants that I have in store-bought potting soil. I also had the top of the soil covered with moss at first and overwatered, creating the perfect environment for fungus and gnats. I replaced the moss with a coarse sand mix to bury the gnat larvae and dry out the soil some. The sand stopped the gnats but after a few waterings the sandy-rock mix sort of formed a concrete layer on the top which I think was further restricting air to the roots. I've since removed as much of the sand mix as I could and loosened up the top layer of soil very carefully. Too early to tell whether it will help enough to save them. But I guess the strongest just doesn't care, the roots must be plowing through the soil.

As for the cutting, it's more for practice than anything. I really just needed to top my healthy mimosa as it was growing so fast, so thought why not try rooting it. I'll keep ya updated on its progress. I can't wait to get into air layering! Looks like such a cool and ingenious process. Thanks for your review and feedback!

 

[Continuum]

You're welcome. I've become a total plant geek, so this is fun for me. (Do I know how to party, or what? )

I don't think my answer about the lights is what you'll want to hear, but here goes. Your best bet for getting mimosas past the seedlings stage is working with mother nature. Start germinating some seeds about 6 weeks before Spring really breaks and acclimate them outdoors for the summer. They should get strong enough in one season to keep alive with CFL's the following winter. HPS (high pressure sodium) or metal halides will be more like what they want for light intensity, but they put off a lot of heat, use more power (and therefore cost more to run), and are more likely to draw unwanted attention than CFL 's, and frankly I haven't been able to keep mimosas happy under even those before the trunks are completely woody and strong.

For your babies that are already growing, just do you best to reflect your lights back on them and hope for the best. Id be happy to point you towards a seed giveaway at STS if you have already germinated all of yours.

 

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You're welcome. I've become a total plant geek, so this is fun for me. (Do I know how to party, or what? )

I don't think my answer about the lights is what you'll want to hear, but here goes. Your best bet for getting mimosas past the seedlings stage is working with mother nature. Start germinating some seeds about 6 weeks before Spring really breaks and acclimate them outdoors for the summer. They should get strong enough in one season to keep alive with CFL's the following winter. HPS (high pressure sodium) or metal halides will be more like what they want for light intensity, but they put off a lot of heat, use more power (and therefore cost more to run), and are more likely to draw unwanted attention than CFL 's, and frankly I haven't been able to keep mimosas happy under even those before the trunks are completely woody and strong.

For your babies that are already growing, just do you best to reflect your lights back on them and hope for the best. Id be happy to point you towards a seed giveaway at STS if you have already germinated all of yours.

Thanks for the offer. I still have about 20 seeds so I'm hoping by the time I get through them that I'll know what I'm doing

I'll definitely be trying to raise them outdoors as much as I can this coming year.

Have you looked into LED's much? My housemate is an electrical guy and is obsessed with them. We were just talking today about switching out the CFL's in the house for LED bulbs because they're cheaper for more light. He has a 3-bulb fixture with 40w LED's that he uses for a cannabis plant. It's their first trial too so neither of us really know what we're doing. I don't think they have enough power for the flower but their plant looks strong.

 

[Continuum]

Good thinking on saving some seeds. Experience really is the best teacher, plus just germinating a small bunch at a time makes it much easier to get a good germ rate. Sometimes it takes some messing with them over several days to finally break dormancy.

I don't know much about LED's, and really I'm not that knowledgeable about lights period. I imagine if you're willing and able to go big with indoor lights you could find a setup that would make em happy. Hopefully someone else can give you some better advice on that.