kostheos

I would like to know what kind of disease is this one. The story is like this: This banana clump has been growing for almost 20 years without any problem. But this summer I have observed damage on leaf petioles and blades on one of the pseudostems. So I decapitated the damaged pseudostem and the next bigger one as well and treated cut points with insecticide (abamectin) in two applications within 15 days. I have inspected also removed crowns through dissection but I have found no signs of bugs (last three pictures). During the rest of summer new crowns developed from those pseudostems and the bigger one has also fruited but the stem has cracked afterwards. During past October I have observed again same damage signs on new leaves (first three pictures). Then I have beheaded all pseudostems plus I cut down the fruiting cracked one, whose base is absolutely white and healthy, and performed dissection on all crowns with following finding: none.. or almost none! I say 'almost' because I think I have seen twice with the angle of my eye by the very recent time after removal of the crowns a very tiny and very thin white thing moving rapidly through the healthy spongy tissue inwards from the exposed point. It was so thin and so white,that I could not find it through some sample dissection, because it could have been very well hidden among every inch of healthy, spongy tissue. If what I think I saw really exists, I am absolutely sure that it was not a larva of a weevil. I know how such larvae look like and I assure you that this thing looked rather like a microscopic worm! Please any help in the diagnose and cure will be immensely appreciated!

dana mastro

neem oil application spray it on and pour some diluted water in the soil that kills and parasitic larvae doesn't always kill the bug but its babys wont survive and that seems to be more of the problem than the bug its self

Abnshrek

Looks like the culprit is a grub.. I remember Banimal's pic's looked like that.. I'd spray it w/ permethrin.. :^)

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sunfish

Spray,spray,spray and spray some more

kostheos

Link please if it is readily available. I thank you all for your help! I have already sprayed with a mix of dimethoat and chlorpyrifos. Besides I have watered soil with 10 lt solution containing 50 ml dimethoat and 15 ml imidacloprid. I do not know however whether a repetition of treatment is necessary or advisable. Still the question remains, where the heck this 'thing' has it come from!?! I am pretty convinced that this pest is hosted somewhere else, since during rest of summer after initial treatment my plants were looking healthy.

bananimal

Here is the link. You have grubs. Look into the petioles where the cigar leaf is emerging. Mix an insecticide solution and pour it in to the petioles. repeat once a week for a few weeks. Don't cut any more leaves off.
Banana Grubby Damage

saturn

I use a LED flashlight to look for pests (in the foliage) at dusk/night. The quality of the light I find great for making them stand out.

They may also be in the soil and since so large, you may be able to dig around a bit and find (and kill) them.

bananimal

Hard to see the grubbs cause they are buried under lots of their poop in the central petiole canal. I scooped it out once and removed the grub with a pair of tweezers. This was on a ladder 10 ft off the ground. At midday so the sun shines down the sides of the cigar leaf. Got down and stomped on him repeatedly. Lots of fun.

They are always in the soil but the only damage I've seen is to the leaves.

A light drench of insecticide now and then works well. In the canal and around the mat.

saturn

10ft ladder, fun! There is always a shadow, or too much light even, and that is why I like the LED light. It just makes things pop. Which, by the way, the grubs tend to do when you squish them. Can squirt pretty far, too!

I just mentioned looking in the soil, as even if you found the one in the leaves, I'd worry about another one replacing it. If you don't mind the drench, that is probably easier.

kostheos

These grubs could be indigenous in my area or they have been 'imported'? I ask because, as I have mentioned earlier, it has not occured similiar disease in the previous 20 years! Only new stuff in my garden this summer has been sheep manure and coir (cocos peat). Is it possible that eggs of this beast had been in yhis stuff?