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Black dots on bamboo leaves

Posted: Wed Dec 21, 2016 9:09 pm
by Tarzanus
I have an issue with my overwintered bamboos. Two of them developed dark brown spots which emerge when leaf gets a couple of week old. Seedling looks vigorous and it started shooting recently. New shoots show the same symptoms. The spots are visible from both sides of the leaf. I sprayed the hell out of them and they do not appear to have mites, aphids or similar insects.

Bamboo on the photo got a bit pale due to nutrient deficiency, but is now turning back dark green after fertilization. Dark spots were there before and haven't stopped after fertilization. When it was outside, it was fine with no leaf damage whatsoever. The spots don't seem to hurt the leaf and when it gets them, they don't spread further on the same leaf and the remaining leaf surface remains green.
bamboo-leaf-damage1.jpg
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Did any of you see similar problem? What could be the cause?

Re: Black dots on bamboo leaves

Posted: Fri Jan 06, 2017 9:55 am
by Tarzanus
Did any of you see something like that on your bamboos? It seems to have started when I took them inside. Airflow is not an issue, RH should not be a problem either. There are no pests on it.
More about it http://cold-hardy.com/bamboo-fungal-infection/

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I hope someone can help me with this one. It does not seem to be holding the seedlings back, because they grow fast, but I am kind of worried. I suspect fungal infection of some kind, but it's strange, because I keep growing conditions as fungus unfriendly as possible. Thanks for the help.

Re: Black dots on bamboo leaves

Posted: Fri Jan 06, 2017 3:09 pm
by needmore
Saw it on my outdoor bananas this year, and I think I see it on bamboo but can check.

Re: Black dots on bamboo leaves

Posted: Fri Jan 06, 2017 9:06 pm
by Tarzanus
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Here's the last stage from above. The bottom side is almost black at this point.

The strangest thing is - leaf seem to do it's job until the end and there are no signs of any wilting or early leaf drop. This is the leaf that would be dropped off, because of the branch that had grown from its node.

I really hope I can get rid of it.

Re: Black dots on bamboo leaves

Posted: Fri Jan 06, 2017 9:21 pm
by needmore
Something bursting the cell walls eh?

Re: Black dots on bamboo leaves

Posted: Sat Jan 07, 2017 4:48 am
by Cooper12
I have that happen on some of my phyllostachys and borinda every year. It goes away in the spring with the new leaves. I just figured it was the cold or the damp of winter. Has never affected anything for me and looks just like that.

Re: Black dots on bamboo leaves

Posted: Sat Jan 07, 2017 4:52 pm
by Tarzanus
It could also be a grow light related issue. I have them under full spectrum (purple) LED light. Last year there were no such issues, but who knows, they may need some time to adapt. I ruled out cold and I'm trying to keep them just slightly moist and force them to dry out between watering. I'll let you all know if there's any change. If not, I'll just spray them with fungicide and insecticide when I plant them outside and hope for the best. :)

Re: Black dots on bamboo leaves

Posted: Sat Jan 07, 2017 5:10 pm
by needmore
For me I can eliminate cold and color of light, I wonder about municipal water constituents.

Re: Black dots on bamboo leaves

Posted: Sat Jan 07, 2017 6:40 pm
by Tarzanus
Ours is around 250ppm TDS (chlorine was eliminated before watering), but I'm now using rain water weekly to flush the soil. Thought about water too, it could be. My first guess was cold rain that soaked them right before I got them inside, but I guess it would go away by now. Soil is random el-cheapo potting soil (peat based with added nutrients, some sand and perlite) which could also be the source of the problem. That's why I started flushing the soil in the first place. I did not go into complete soil flushing because they grow OK, it's just that browning.

Re: Black dots on bamboo leaves

Posted: Sun Jan 08, 2017 9:44 pm
by Nicholas
I've had/have some related problems with brown streaks on the leaves of phyllostachys edulis 'bicolor' when it was growing in a large pot.
Attached is a picture where you can see some of the damaged leaves but it is not a great shot.

The plant was overwintered in an unheated room with enough sunlight but the leaf problem persisted even when it was brought outside in spring and only got somewhat better when I planted it into the ground in summer.

It may be some kind of virus or fungal infection.

Either way, with the current cold spell here in Austria I'll be lucky if the bicolor survives at all (it was tarped but not very well).
At least the other boos look pretty in the snow!

Re: Black dots on bamboo leaves

Posted: Sun Jan 08, 2017 11:57 pm
by needmore
Nicolas, how cold is it?

Re: Black dots on bamboo leaves

Posted: Mon Jan 09, 2017 12:35 am
by stevelau1911
Based on my observations over the years, the checkerboard spots only occur in the late Autumn into winter, more so on young moso seedling leaves and I believe it is a combination of cold temperatures, relatively strong light shining on cold leaves, and the root system unable to supply water to all the leaves thus making the older leaves tend to get more spots. I don't think it has anything to do with viruses, pests, or humidity. Bring the plant back outdoors the following spring, and the new leaves should not have that problem. I have seen some seedlings that did have an ongoing problem through the summer before, but when I checked the roots, there was fungal problems underneath, and stunted root growth on plants that weren't big enough to handle it yet.

Nicholas, on your bicolor, one thing I would be very careful about is it's drainage because moso tends to have very small tender roots despite it's large size potential, and mine nearly got killed by flooding which is why it is now growing on a raised mound. Actually I just trained the rhizomes to grow higher. It's leaves will brown and die off if it gets flooded early in the season when standing water is more common. Here's the entire Journey since I've had it, and it should be bouncing back well this year. http://stevespeonygarden.blogspot.com/2 ... -from.html

Re: Black dots on bamboo leaves

Posted: Mon Jan 09, 2017 8:24 am
by Nicholas
@brad - Temperatures were only around -12*C but we had extremely strong winds so it is hard to tell. I'm guessing vivax will also not be happy about it but it will take some time until leaf damage will show. Especially because it has been constantly well below freezing here for over a week.

@steve - I've been following your progress with bicolor for quite some time now. While it really sucks that your beautiful plant was damaged so badly by water-logging at least it will hopefully help others to avoid this issue. I've made a mound of very sandy clay soil into which I planted the bicolor, amended with lots of horse manure. Also I basically wrapped a huge webbing of wire mesh around the existing rootball to make sure the darned voles don't prematurely end my little experiment.

Re: Black dots on bamboo leaves

Posted: Mon Jan 09, 2017 9:51 pm
by Tarzanus
Nicholas, we have no snow, soil is frozen down to 0.5m and temperatures dropped down below -15°C. This year I decided not to protect my Borinda. I don't think I even have anything to protect by now.. :P

Other bamboos are doing very well. Especially the Moso seedling which showed no leaf curl until recently. Soil is frozen quite deep by now, so it will most likely start to decline. I'll see when it thaws, Temps are well below -5°C during the day as well. And the darn wind...

Re: Black dots on bamboo leaves

Posted: Mon Jan 09, 2017 9:58 pm
by Tarzanus
The damage on your photo is different. I've had that as well. That's the thing Steve talks about and my young Moso seedlings were dying because of this issue constantly. I think it's caused by bad drainage, too large pot and root damage caused by anything - in my case overheating of black pots.

I have misted the bamboos for the last 2 days and I think the issue worsened considerably! I'm now almost certain its some kind of fungal issue. Root system is established by now and should not be an issue. While watering, I noticed even more rhizome/shoot buds inside, they are exploding, they just look a bit crappy... I'll use copper based fungicide, I think I must have it around somewhere.