Gardening with Wilson

The dwarf banana plants have been my pride and joy in my Ginger Garden. Recently, out of a sudden, I noticed two of my plants started to yellow and the pup that was growing beside one of these plants started to die back. This is not the first time that this happened. It occurred to another larger banana plant and a Bird-of-Paradise plant that were grown in the same garden.

An apparently healthy banana plant that started to turn yellow and die away.

When I uprooted the affected that banana plant, the pseudostem gave way very easily and what I saw was a black coloured, rotten mess inside the stump. It looks like rot and there were numerous tunnels that ran through the mushy remains of the pseudostem.  

The base of the pseudostem of the affected banana gave way very easily and the soft, musy tissue seemed to say that the plant was affected by rot.

This symptom was also seen in my White Bird-of-Paradise (Strelitzia nicolai) that was planted in the same Ginger Garden. The plant showed the same signs and died in the same way some time ago. The growth of my Bird-of-Paradise plant first slowed down and then, its leaves started to turn yellow. One day, the entire plant just collapsed at its base. When examined, the base of the plant exhibited the same rotten mess and presence of numerous tunnels. Some areas exuded a gummy substance.

Notice the three holes inside the pseudostem? They are the tunnels that have been made along its length.

As I was trying to uproot the stump of the dead banana plant, a small, white but fat grub started to crawl out from one of the holes. It was then that I knew what was the culprit that made the numerous tunnels that probably caused the death of my Bird-of-Paradise and banana plants!

I took a photograph of the evil grub and did a search on the Internet and found that it could either be the larva of the Banana Stem Weevil (Odoiporus longicollis) or Banana Weevil (Cosmopolites sordidus). From the pictures that were available online, I cannot really distinguish the two. The reported symptoms of affected plants are also relatively similar.

As described earlier, the base of all my plants that were affected by the Banana Stem Weevil/Banana Weevil were rotten. From published literature, that could be due to secondary infection caused by fungi or bacteria present in the soil or surroudings. Moisture in the soil during the rainy season could have accelerated the advancement of the disease.

The culprit – larva of either Odoiporus longicollis or Cosmopolites sordidus.

Very detailed discussions are given in the articles that were published by Banana Bioveristy International. Click on the links below to learn more about the Banana Stem Weevil (Odoiporus longicollis) or Banana Weevil (Cosmopolites sordidus):

Banana Stem Weevil (Odoiporus longicollis)http://bananas.bioversityinternational.org/files/files/pdf/publications/pest5.pdf

Banana Weevil (Cosmopolites sordidus)http://bananas.bioversityinternational.org/files/files/pdf/publications/pest4.pdf

Stated in the e-pamphlet below, Confidor is an insecticide that is indicated for use to control weevil damage. It is commercially available here but is an extremely toxic systemic pesticide. Confidor can also be quite expensive to use large-scale:

http://apepuganda.org/downloads/Publication%206%20THE%20BANANA%20WEEVIL.pdf