What’s That Black Stuff Growing on my Bamboo?

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What’s That Black Stuff Growing on my Bamboo?

So you bought a beautiful bamboo plant and planted it in your yard.  It grew nicely for the first year or two and now suddenly you have noticed all kinds of black stuff growing on the bamboo.  It’s all over the place, but especially in the creases of the branching.  It’s unsightly and sickly looking, and you don’t know what to do.

aphids on bamboo
Aphids an bamboo

Well never fear, that black stuff growing on your bamboo is what we like to call black sooty mold.  Black sooty mold forms as the result of a fungus growing on the residue left behind on the bamboo.  My experience here in Florida is that this is most common from an aphid or mealy bug infestation, and even more so is compounded by the ants that have formed a symbiotic relationships with them in order to harvest that sweet nectar.

So now that you know what the black stuff growing on your bamboo is, here is my proven method for getting rid of it and controlling it.

  1. Remove the existing black sooty mold.  This is relatively easy and can be accomplished in no time using a water house and some household dish soap.  Simply add the dish soap to a one gallon garden sprayer and thoroughly coat the areas that are covered with the unsightly black sooty mold. Allow it to soak for a few minutes, then blast it off with the garden hose using a high pressure stream of water.
  2. Treat the infestation.  Whether it’s aphids, white fly or some other pest, you will need to treat the bug that is creating the environment that allows the black sooty mold to form in the first place.  After you have cleaned the sooty mold from the bamboo and it has dried, add horticultural oil to your pump up sprayer and apply the mixture to all the branch nodes (typically early in the morning).  Next, spread a good layer of used coffee grounds around the plant and work it into the leaf mulch.  Coffee grounds act like a natural systemic pesticide, and you can get them for free if you are not a traditional coffee drinker from Starbucks and other coffee houses.
  3. Regular maintenance.  Keep a watchful eye out for any pests, in particular those pesky little ants.  As I mentioned above, ants love the nectar left behind by the aphids, so this is a sure sign that you are on the verge of another infestation.  Regular applications of horticultural oil and coffee grounds will help to minimize your chances incurring just such a thing and thus keep your bamboo black sooty mold free!
ants harvesting nectar from aphids
Ants harvesting nectar (photo courtesy Roy Rogers, Tampa FL)

One extreme method for removing black sooty mold from your bamboo is to also remove all the existing culms.  If you should decide to go this route just know that the pests will often go into the ground and wait for the new shoots to come up and thus create a new infestation.  Therefore, treatment of the bamboo after the culms have been removed is still necessary to eliminate the pests.

One final solution is to get rid of that species of bamboo.  Of the fifteen or so varieties of tropical clumping bamboos that I have in my landscape, on the the Bambusa multiplex varieties seem to attract pests that contribute to the formation of black sooty mold.  Therefore, if you are a bamboo lover like myself, simply plant those that are not as susceptible. such as Bambusa textilis mutabilis or Bambusa textilis gracilis.


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