I have observed many groves of yellow groove, many which happen to be smaller in size than my juvenile groves, and I believe one of the main reasons is that the old culms never get thinned out.

One thing I have done over the years when I take field divisions is that I take culms of differing ages. One thing I've found that seems always hold true is that the youngest culms in the grove seem to be the only ones capable of producing decent sized shoots from either a fall or spring dig. This might mean that bamboo culms can only store a lot of starches in their new culms produced on their 1st year. The 2nd year and older culm divisions usually either die off, or they took another year to gather enough energy for decent shoot production. Another explanation may be that the rhizomes attached to the new culms happen to have more energy stored, and viable shoot buds to release it.

If older culms are not nearly as efficient in holding starches inside the culm, does that mean that the energy gets transported directly into the newest rhizomes? I think a 2nd year culm which is the same size as a 1st year culm should be producing more energy throughout the spring and early summer while the 1st year culm hasn't produced any leaves yet. By the 3rd year, my guess is that the culm loses efficiency in energy production since its tap roots get old, and it takes longer to transport energy to the newest rhizomes. In a mature grove, I believe that these older culms eventually become a liability to the entire grove as they will transpire water, and provide very little photosynthesis. This brings up the question of when they should be culled out.


My guess is that at any given time, more than 90% of a mature grove should be composed of 1st, 2nd, and 3rd year culms to stay healthy.

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What you're talking about isn't photosynthetic activity - it's starch storage capacity that may reduce eventually when culms get older. Even if they could hold only minimal levels of starch or any other smaller type of sugar, they could produce enormous amounts of sugars due to whole bunch of branches and leaves. Photosynthetic activity is usually determined by leaf surface and not amount of reserves that can be stored inside the plant tissue. If it's true and mature bamboo culms loose their "food storage" capability, then everything plant produces goes directly into rhizome growth or gets stored in surrounding "fresher" culms.

Someone with an option to make sugar content analysis in culms of different age should have no problems determining if there in fact is any difference.

That kind of makes sense that it depends on the leaf surface for the total photosynthesis of a culm on any given year. They wouldn't produce new leaf buds and re-leaf if they were useless. I think if photosynthesis is completely dependent on leaf surface, then 2nd year culms would be the most efficient since culms will continually shed their leaves from prior years, and grow smaller ones with less leaves per branch. Culm and branch damage from harsh winters may also diminish the energy producing capacity of a culm as it ages.

I am pretty sure that their starch storage capacity goes down as culms grow older because divisions from the newest culm divisions seem to always outperform the divisions with older culms. Energy storage capacity is probably irrelevant to the photosynthesis production. The problem I see arising from too many old culms in the grove is that they start taking up space, transpiring too much water, and prevent new shoots from rising in the spot they are growing.

I think for a young bamboo, it is probably best to leave everything alone for the first 4 years or so just because the congestion underground hasn't started yet to become an issue yet, but once it does, it may be helpful to get rid of some of the older culms. Older culms can probably provide photosynthesis very well which is helpful in getting a bamboo started for the first few years, but at some point, I believe that starch storage capacity of the grove becomes more important.

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http://stevespeonygarden.blogspot.com/

I think it only took you 3 years to start giving this advice that you were given at that time

I think you are confusing rhizome age with culm age, you can not tell how old a rhizome is based on the age of the culms and rhizomes make shoots not culms. I get that there is a correlation between culms and how they feed the rhizomes but I don't think you should base the success of your divisions based on how old culms, are rather it is the rhizomes.

I suspect I am about to botch the data I was given by a very experienced veteran grower but he maintains something loosely along the lines of:

1st year rhizomes generally will mature around 10% of the buds into new growth; 2nd & 3rd year more like 30% each year, 4th year 10%+ or less, and older not a whole lot. So if he is correct then most growth comes from 2nd & 3rd year rhizomes so grove maintenance should be intended to allow for a healthy rhizome replacement cycle, which gets trickier when people use barriers/beds.

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Brad Salmon, zone 5b/6 Southern Indiana
Winters -20 to -25C. Summers 30 to 35C , humid. 115 cm annual precipitation, frost free from May through early October. 259.3 meters elevation. Growing 150+ species. http://www.needmorebamboo.com/

That sounds like it makes sense since the newest culms are usually dug with rhizomes attached that will be 2-3 years old by the time they are supposed to shoot in the spring. Some of the possible reasons why older culm divisions performed so poorly aside from the age of the culm and storage capacity is that the roots and rhizome systems may be too old, or there might no longer be any viable buds attached which lead to failure.

I don't treat all my bamboos the same, and I have noticed trends where the new groves that are left alone tend to have an edge in shooting performance over the ones where all the culms from prior years are continually culled. This is especially true when I had hundreds of moso seedlings as the ones that were never thinned out from the start tended to upsize better and produce more shoots.

The time in which culms need to be culled likely vary from species to species. Something like yellow groove seems to have the capability of producing a very thick solid mass of roots & rhizomes within 1-2 years of growing in that area while something like dulcis may take many more years to become congested under the grove.



Another thing I have wondered is how long it takes for old roots/ rhizomes to completely rot down after a culm is culled, and whether or not a grove will remain on the same rhizome system given that it is contained in a 100 square ft area. I think it does stay together as you usually won't see a mature grove decline over the years as long as it is well maintained. I don't know exactly how it works, but my guess is that the bamboo chooses a main network of rhizomes that gets priority over all the other rhizomes.

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http://stevespeonygarden.blogspot.com/

Steve - Check out Inbar's China Bamboos in 2 parts. Especially interesting is • Growth of a Bamboo Stand • on pages 79 & 80 in Part 1.

I'll pm you the two parts.

john

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johnw coastal Nova Scotia