Culm tip desiccation?

[brotajardin]

I've posted this on the Bamboo Plantations Group, but I'm hoping that someone here might have an insight as well.

I have an interesting issue with two different bamboos. The bamboo are located on our farm near the Gulf of Mexico in Texas.
The two species are completely different but are both cultivated as ornamentals.
The plants are Phyllostachys vivax 'aureocaulis' and Bambusa dolichomerithalla 'greenstripe'.
The symptoms are similar, but slightly different.
I am wondering if anyone has had any experience or seen what I can only describe as tip desiccation.
It manifests itself slightly differently with the two species, but the end result is similar, plants with half dead culms.
The phyllostachys only begins to dry and curl it's leaves in the bright sunlight.
THIS IS NOT DUE TOO LACK OF WATER IN THE SOIL! We have already received over 70"(180 cm.) of rain this year.
The soil is saturated at the moment and the plants' leaves dry and curl and ultimately die when the sun comes out.
When there are clouds, the leaves are green and vibrant. This only happens on the top half of the culm as well.
Seeing this, I tend to think of some sort of pest either in the culm, or at the roots possibly?
However, I have not been able to see any pests.
And finally, all culms are not affected, only some.
It seems to be spreading though?
The Bambusa dolichomerithalla has a similar, but different situation where the newer culms just dry and and die starting at the tip and going maybe a third of the way down. Of course, these are culms fully extended, and branched.
They don't respond in the same way to the sun, but the culms definitely just dry and die.
Any insights would be appreciated.

david cater @ the utility research garden

[Mark Meckes]

Hi David,
Are current or last seasons culms affected or both?
With the excessive amount of rainfall we've had this year I'm wondering if it might be associated with oversatuturated soil.
What is the contour of your land and soil type, and is there standing water that stays around for days after a rainfall?

I'm not experiencing this problem myself, but then our bamboo is mostly growing on a hill, and on our flat land the rainwater drains within a day.

If you can provide pics you can upload them as attachments with your post.
(Below message text box > Manage Attachments > Choose File > Upload)

Mark

[brotajardin]

it seems to be on the first year culms that are drying. Although there is an EXTREME amount of moisture this year, the same thing was occuring last summer as well when we had slightly less rain. So I don't think that it can be attributed to being waterlogged, although I would not rule out anything. The soil, although practically without any relief, is a loamy moderate draining alluvium generally great for growing bamboo. And of course, we have other Phyllostachys species on the farm, probably 25 different species and none of the others show this same pattern. That said, not even all of the Ph. vivax 'Aureocaulis' acts the same. I originally planted 10 different divisions dug from a single original plant, to begin this grove, and one or two seemed not to be affected by this problem of drying tips? This leads me to think of an insect pest, but????? I will post pictures in a few days.

[Mark Meckes]

Trying to diagnose a symptom caused by below ground problems is difficult.
If culms die right to ground level, a couple things one can do is dissect a culm and see if they are waterlogged.
Also check to see if the attached rhizome shows any indication of decay.
A fresh rhizome should be a lustrous ivory, and a waterlogged rhizome might show brownish discolorations.

I have seen/visited several scenarios of Phyllostachys species, particularly on P. viridis and P. bambusoides where the new culm leaves soon dried, remaining on the culm for some time as a parched brown/tan.
I'm unsure if this was do to some type of culm rot.

Here is an example of Phyllosatchys bambusoides in Georgia that had waterlogged culms:
http://www.bamboocraft.net/bamboo/data/548/thumbs/PbambusoidesD3BGA050216-711.jpg (http://www.bamboocraft.net/bamboo/showphoto.php?photo=1584)

For reference I should also mention ...
- Natural cause, when the planting overproduces the number of shoots that it's rhizomes can sustain.
Bamboo has a tendency to overproduce as an insurance in case some shoots are damaged, destroyed or if there isn't sufficient sunlight/nutrients etc to sustain all the culms. It is usual that a percentage of culms in a grove will abort.
Often selective thinning, results in a lower percentage of aborting culms.

The main difference here is that you should not see culm dieback continue on to other culms that have sufficiently leafed out.

Mark

[ShmuBamboo]

Here in the land of rain, I can attest that rainfall alone is probably not the cause. It may be a combined factor with some other pest, or environmental condition like heat, however. Last year we had over 8 ft of rain here, and this year about 6 ft (rain year here is Oct 1 to Sept 30). We had a foot of rain here last May, and 2 ft in November. Soggy conditions. The bamboos I grow (with the single exception of Black) are seemingly immune to rain amounts and flooding, and growing in muddy conditions.

I only have the Phyllostachys vivax species and not the other bamboo that you have. My vivax seems to be rather more immune to rainfall and temperature extremes here... if anything, Phy. nigra types (Black and Henon) seems to be the most susceptible to drought and flood. The leaves droop openly and perpendicular to the leaf length with too much water and curl closed parallel to the leaf with too little water. Then they typically burn back about 1/4 from the tip every year, no matter what happens. This leaf tip burning seems to be attributed to the species though, and not environment.

Mark shows an excellent photo of an overwatered drowning Phy. boo plant. The effects would be more over the entire plant, and not just the end sections of culms. I would suspect something inside the culms like a boring insect. Or some type of sucking insect that has done its damage when the culms were shooting, and the effects are showing after they branch and leaf out. I would examine the break points carefully with a low power scope or glass, and split a cane in half the full length and examine the inside sections for signs of bugs.