Not insects...looks like inconsistent watering.

Are you sure about "inconsistent watering"? I'm watering it on a pretty consistent basis.

If you think you're watering properly, let me ask: Is that a potted bamboo? If so, it could be rootbound, which would prevent effective watering from occurring. Also, what is the species, and kind of sun does it get?

Yes, it is potted bamboo. The pot is big but as the shop where I bought it told me it might be fungus and that I needed to check that there was proper draining I dig to check out the roots.

I did not notice anything special but I can see that the roots still have the shape of the previous container it was in (where I received it). But I doubt there is anything I should do here?

It is a Phyllostachys and getting south east most of the day sun, also quite a lot of wind as I am on the 10th floor.

One other note, I noticed so brown marks on one of the main bamboo trunk, but is does not appears on others: https://www.dropbox.com/s/et7vaaej4s4hzkt/2014-12-28%2017.32.24.jpg?dl=0

Thank you!

I don't think it's rootbound, based on that picture. I also don't think that the marks on the culm mean anything (some bamboo, like Ph. violascens look like that as they age). Continusing exposure to wind, however, can cause dessication, and result in exactly the appearance you are concerned about.

Necrotic leaf tips and margins in all containerized plants are usually symptomatic of a drought response, almost always caused by 1 or more of A) over-watering B) under-watering, or C) a high level of dissolved solids (salts) in the soil solution. A fourth cause in plants sensitive to certain chemicals (fluoride, e.g.) would be D) a build-up of those chemicals in tissues. I would eliminate those possibilities before looking any further. Your soil should allow you to flush the soil at will to eliminate accumulating dissolved solids; this, w/o your having to worry about the soil remaining saturated so long that it impacts root health and root function. If you can't water appropriately, you'll be in a constant battle with your soil for control of your plants vitality ...... for the life of the planting.

Al

Thank you for your answers.

I removed the plant a bit of the fence to prevent wind, see how this goes.

Also I want to go over each the possibility that has been supposed and see if I get rid of them correctly via a good diagnostic:
A) over-watering
I could not find any soggy part, the bottom soil of my pot is humid but not dipping in water. Good enough?

B) under-watering
My soil is humid except for the top half first inch. Good enough?

C) a high level of dissolved solids (salts) in the soil solution. A fourth cause in plants sensitive to certain chemicals (fluoride, e.g.)
Here are the ingredients of the soils I am using, I do not see salts or fluoride listed in them but I might be missing something else?
https://www.dropbox.com/s/3f372yanxl484jt/2014-12-29%2011.30.55.jpg
https://www.dropbox.com/s/ikh2eu9vtr4zdq5/2014-12-29%2011.31.11.jpg

D) a build-up of those chemicals in tissues.
How can I diagnose this?

In general, does the soil being used have a bad balance for bamboos?

The plant isn't basically healthy, it's basically stressed and showing symptoms of that stress. Distal leaf tissues usually as a direct result of the plants inability to move enough water to those tissues to keep them hydrated due to compromised root health/function, which most often occurs for the reasons outlined; plus, there remains the possibility of chemical or nutritional toxicities. Wind, like low humidity, might be an exacerbating factor, but I highly doubt it's the primary issue. Also, how much a plant tolerates isn't a very good gauge of what it likes. Plants don't operate well at the limits of what they are genetically programmed to tolerate, and when they grow under that sort of stress we should expect to see symptoms made manifest.

SK - You can tell if your soil is retaining an excessive amount of water by watering to complete saturation, waiting until the soil stops draining, and then tipping the pot at a steep angle. See fig A & B:
{{gwi:5807}}

If a fair amount of water exits the drain after you tip it, your soil is holding more water than the plant prefers. There are ways to fix that, but I don't know how far you want to chase this issue. I'll give you as much help as you want. A VERY high % of issues that impact the vitality plant are caused by soil choice or nutrition. You can learn How to Deal with Water-Retentive Soils, or much better - learn how to avoid them altogether. Your plants will thank you.

The fertilizer charge in your soil is appropriate, but Miracle-Gro potting soil has a poor reputation because of its excessive water retention, and dissolved solids from fertilizer solutions accumulate in soils when you aren't flushing the soil when you water. Soils like MG force the grower to choose between excess water retention or the accumulation of dissolved solids that accompanies watering in small sips in order to avoid soggy soils. Both choices are poor choices.

Do you have a water softener? If so, what kind?

It's hard to diagnose a toxicity issue unless you know what the plant might be sensitive to, and w/o some history of what your nutritional supplementation program has been like in past months. Sometimes, knowing how the plant has been tended reveals clues that point directly to a likely cause, but in this case, so far, there isn't enough info.

Al

Thank you for your answers.

I bought wood barks and added about 1 inch in the bottom of the container. I also changed the soil with new one and that was the opportunity for me to check thoroughly the roots which looked good to me.

I do have a water softener, Culligan FM-15RA Level 3 (http://www.amazon.com/gp/product/B00006WNMJ/ref=rcxsubs_mys2_product_title), however I am not using it for plants. Should I?

I am adding a bit of fertilizer that the shop where I bought them advised me, I don't have the box anymore so I required them to send me the reference.

I've also read about using hydrogen peroxide in the water to have more oxygen going to the roots, is that something you advice?

sylvain-
The roots look fine and you shouldn't have to baby it with exotic things like hydrogen peroxide. This is a bamboo, not an orchid or other sensitive plant. Others here are suggesting what I consider to be complex treatment of a minor issue. They are entitled to their opinions. I am currently growing over seventy species of bamboo, in the ground and in pots, and have been doing this for years. I have never had to do anything very complicated for them to do fine.

I once gave a healthy, potted Phyllostachys to a friend who placed it out on the balcony of his mid-rise condo. Even though our climate is temperate, after about 6 months, it started to look like yours, due to the winds. You should feel free to do whatever you want to your plant, as none of the treatments will do any harm, However, if you still have the plant exposed to dessicating winds I predict that it won't be much improved in the coming months, regardless of what other things you have done to it.

Good luck. It would be interesting to hear back from you after you have nursed it for a while.

Thank you for you answer.

I understand that bamboos are generally pretty tough plants and that is also why I choose them and I also understand that they don't like wind, unfortunately that is something I won't be able to change because I only have one balcony and I can't stop the wind.

So I'm hoping I can balance the wind effect by taking good care of all others aspects that a bamboo would like.

I feel I've pretty much done the maximum I could, I even bought new soil that is light and not supposed to hold water. If it does not work then I will need to consider bamboos that don't mind wind. Any suggestions?

I'll keep you guys update on how the bamboo is doing.

Cheers!

It's very difficult to 'buy' a soil that doesn't hold water in excess, for the simple reason that water retention is directly linked with the size of the particles that make up your soil. Soils that are based on fine particulates, like peat, coir, compost, composted forest products, sand, topsoil ..... are inherently excessively water retentive.

You can improve your success to a fair degree by putting into practice the tips in the link I left above "How to Deal With Water-Retentive Soils". If you can't water your plant to beyond soil saturation w/o having to worry about impaired root function, it's a certainty the soil will limit your plant's ability to realize its genetic potential. If you're serious about learning how to grow proficiently in containers, this link about Soils and Water Retention offers information that represents the largest step forward a container gardener can take at any one time. I posted it originally in 2005, and it's been very active ever since. I'm certain it will help you understand the importance of having the right balance of water and air in your soil, and how to avoid the limitations imposed when that balance isn't favorable - from the plant's perspective.

Al