Big bug eating the roots
 

Quite a few of my plants have been looking less good than they used to, and when fruiting have barely made it to ripe bunch time. I had put it down to a soaking wet winter and my inattention to fertilising. However on cutting down some of the plants because of their poor condition, the roots have been drilled by several somethings that leave a half inch hole. We couldn't find the culprit. K J - you are in my neck of the woods - have you seen anything like this and if so, do you know how to get rid of it? There appeared to be no drill holes on the outside of the trunk that we could see.

Re: Big bug eating the roots
 

look at.. pr giants.. last post on boring weevil..sounds like you might have same problem...

Re: Big bug eating the roots
 

Well - there is no sign of anything from the outside. I did consider Japanese beetle but there are no damaged leaves anywhere in the garden, and there are no beetles to be seen. The damage does look as though it could be caused by a huge grub.

Re: Big bug eating the roots
 

I've never seen any bug that eats the roots, from what I know about weevils they only attack the corm and the lower part of the pseudostem.

Re: Big bug eating the roots
 

Sorry - I didn't make myself clear - yes, the corm and lower stem were drilled. If this sounds like weevils - is there a remedy?

Re: Big bug eating the roots
 

Yes, it sounds like weevils. From what I understand only pretty awful chemicals, which may not even be legal in many areas for a home gardener if at all. Some have suggested using neem pellets or powder. I've also read that you can put sand around the base of the corm. Diatemaceous earth may help, but as soon as it gets wet it's useless. What I do is every time I cut down a plant, I cut the p-stem into foot long chunks, split them, place them split side down near the corms, then check daily for weevils and crush them. Doing this consistently, over time the number of weevils I find has dropped, and there seems to be less clear damage when I initially cut off the p-stem. The problem seems to be having enough p-stems available to use as weevil traps.

Re: Big bug eating the roots
 

More Photos
http://www.bananas.org/f2/african-rh...vil-17211.html



This is what weevil damage looks like.



What banana cultivars are they attacking?

I only have a problem with my Cuerno de Alce, my Maricongo, Manzano, Morado, and Cavendish have never had weevils.

What to do depends on what you prefer, GrubEx is commonly used here.
Scotts GrubEx1 Season-Long Grub Killer

I prefer to keep the area clean and encourage ants to move it, but not the big black ants. They'll drill more holes in the pseudostem than the weevils.

Damaged caused by large Black Ants.


The RD may permit the use of Carbendazim, but it was banned in the US for health concerns and countries that do allow it's use can still export bananas to the US.

Using Pseudostem injector for effective control of Fusarium wilt, Erwinia rot and Weevil attacks. ~ Tissue Culture Banana

Check with the local farmers and see what they use.

Re: Big bug eating the roots
 

From what I understand the pseudostem traps are used to monitor the problem and not as the solution. The traps will continually have more eggs hatching and killing them one at a time sounds more like using your fingers to plug the holes in a dyke.

Re: Big bug eating the roots
 

If they're not close to blooming and used as ornamentals, try some of the systemic rose and flower care with imidacloprid or acephate, use it as a foliar spray and a drench around the base of the plant. It will take 3-4 weeks to travel through the entire plant and take effect.

Re: Big bug eating the roots
 

I left out the part about making sure to throw away the cut traps within a couple weeks before the eggs hatch! Otherwise you are just giving them new places to breed.

Anyway, I can't imagine it would be a viable solution for large scale growing. I wonder what they do on organic banana farms? I am just following the suggestions of the Kepler & Rust book on bananas in Hawaii. It seems to have helped in my specific situation. They attack mine at different amounts too. Ice Creams and any of the Hawaiian varieties (Iholenas, A'ea'e) I have seem to be damaged the most. Dwarf Brazillians seem to have lots of them, but the grubs don't seem to cause damage beyond the outer layers of the p-stem.

Re: Big bug eating the roots
 

General Information on Pest and Damage

www.infonet-biovision.org - Banana weevil

I could never throw away any part of the banana plant, I can't even throw away a banana peel.

I crush and dry the pseudostems, and use them to amend my soil.

Annually I spend $0.00 on fertilizer.

Re: Big bug eating the roots
 

Thanks K J and Rob for all the extremely useful information and K J for the pictures. Looking at the beetle damage in your corm picture K J, I am struck by the apparent small size of the holes - mine must be around a centimetre across (4/10 inch) and the plants that I have found to be affected so far have been Saba and Blue Java, although now I am looking suspiciously at some of the others. None appear to have any problems with new pups - the plants start to look sickly at around flowering time. In the morning I will have a closer look at the grub holes and get some pics. I am not sure what chemicals are available here but all the information will be very helpful. Thank you.

Re: Big bug eating the roots
 

Carol you don't need to look at the plant to know if you have weevils.

I can tell merely by applying lateral pressure to the pseudostem, the amount of resistance is a much better and quicker indicator.

Re: Big bug eating the roots
 

It has been pouring with rain the last 2 days, so no pics until it dries up - but I have been out briefly and applied some lateral pressure and quite a few pstems are rocky to say the least!! Hmmm!

Re: Big bug eating the roots
 

Banana corm weevils were not a problem in Santa Barbara. Then I moved to Hawaii. They attacked several plants. I dipped the plants in a bleach solution that I thought for sure would kill them. The plants made it back after looking like death. My plants were potted and could be treated. I now spray a solution of water and Dr. Bronner's peppermint soap weekly on all of my plants. I have caught the little bastards and sprayed them and the soap kills them. It also kills white flies and other pests. It's safe and organic.

Re: Big bug eating the roots
 

Thanks Andrew, I am going back to England for a brief visit shortly and I will see what remedies I can find there.

Re: Big bug eating the roots
 

Safe travels!!