Browning of Leaf Tips (Phyllostachys nigra)

[Paolo]

I have Phyllostachys nigra growing in 1/2 wine barrels, outside in Oakland California. This is the third year of growth and they are sending up strong, active culms each year. This year, I got the largest culms yet, but in each of the three barrels, the older, established canes are exhibiting browning leaf tips. The canes that are experiencing these are not showing signs yet, of generating new leaves.

My sun and watering have not changed - I use a drip irrigation system and they get partial sun. I haven't tested the soil acidity. I assume they are getting root bound, but I've read that they like to be crowded a bit. I plan to thin a bit this winter.

When explosive new growth is happening, is it common for the older culms to experience the tip browning and drop leaves?

There are two images below.

Thanks!

http://www.mmotion.com/plants/bb01.jpg

http://www.mmotion.com/plants/bb02.jpg

[Mark Meckes]

Hi Paolo,
Have any new leaves from branch buds appeared since these photos?
If not, then those culms are in decline and energy is being diverted to new growth.

Leaf-tip browning can be caused by many things, the first being the annual process of older leaves being replaced by new leaves.
This comes at a time when new shoots are also forming, so the bamboo directs it's energies to shoots and new leaves and diminishes the supply of nutrients to older or weaker culms
As older culms mature and less new leaves form on the branches, the browned tips become more visibly obvious.

Age of culm at maturity
In a grove, bamboo culms can live for 5-10 years - some live less - some live more.
Growing bamboo a contained setting, the life duration of a culm will be less then 5-10 years and selective thinning may be required to give sufficient distribution of nutrients to the remaining culms.

Understanding the causes that may be related to leaf tip browning requires looking at conditions that occured during the life of the leaf. ... the amount of sun/shade, wind, hi/lo temperatures, moisture regularity, water alkalinity, soil ph/nutrient availability, insect pests and plant disease etc.
Hardest to decipher are small incremental events and conditions that only becomes most apparent when the bamboo diverts energy to new growth.

Are you getting browned tips on new leaf growth?

Mark

[Paolo]

Hi Mark,

Thanks for the reply. There is minor new leaf growth since the photos. The new culms are growing rapidly to the point of leafing, and of the small ones present, they look green and healthy. I suspect you are correct that the energy is being diverted toward the new culm growth. There is no evidence of insect pests or plant disease.

The rhizomes are becoming plentiful enough that they are circling the container, looking for escape. In their dormant period, I assume it is acceptable practice to thin the rhizomes, or should I just remove culms and not mess with the roostock?

Paolo