louis14

A few of our Gros Michel plantlets had yellowing leaves so we checked on them and found these very large grubs feeding on their roots, in the growbags.
According to the staff, they are Rhino Beetle larvae.
I don't think there are too many to represent a danger for the thousands of plantlets in our hardening tent but we are taking action to try and get rid of them. Any experience of a similar problem and it's remedy will be much appreciated.
And..can you beat our size?

edwmax

Gee ... those beetles get very big. They are sub to the scarab beetle family. From my quick google, the larvae only eats decaying plant matter. But the adult will feed on fruit and plant sap. The adult can damage your plants. And they are nocturnal. They move & fly at night and hide during the day.


So beetle traps are needed to know when the beetles are active in your fields and when to apply insecticide to eradicate them. ... I think these could be a BIG problem for you.


A side note: There are some folks that keep these for pets. And others that eat the grubs for snacks. You could sell the grubs.

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Akula

That's nasty!! You need put a warning in the title!

Hopefully the guys who commercially farm have some solutions but I have encountered grubs in my lawn. I knocked them out with a product called Bayer 24 Hour (Trichlorfan) after infestation the first year. This year I tried to get ahead of the game and used a product called Lesco Bandit (Imidacloprid). I had good results with both. Sevin (Carbaryl) is suppose to be pretty effective also but I couldn't find it in granular form for application.

My understanding is that you need for the pesticide to get below the surface where the grubs are active and not a surface pesticide. Imidacloprid can effects bees (kills/interferes with reproduction) so it shouldn't be used prior to time of flowering so probably not a good one for bananas although pretty good on St. Augustine grass.

Here are a couple articles that I used:

How to choose and when to apply grub control products for your lawn | MSU Extension

https://ag.umass.edu/turf/fact-sheet...e-grub-control

louis14

Lol
We don't use any neonicotinoids on the plantation as we rely on bees for our Longan and our Mangoes.
It is also a problem to get to the actual soil as the bags are hidden by the leaves and there are many bags to be handled.
We are first testing a mix of standard pesticides to be heavily sprayed on all the plantlets in the tent, followed immediately by heavy watering with the rain nozzle so as to drain the pesticide down into the bags and surrounding areas.
We'll watch and see if the problem stops. The hatch is seasonal according to local information; we are in the middle of it.

I'll check if the staff are going to eat them, they didn't seem too interested so maybe they don't taste so good

Akula

You might review your operations to minimize any attractants for the beetles. I think they are attracted to light at night. They fly into the glass of my French doors fairly aggressively when I am up late watching tv or reading. I think they were also attracted to my pool light at night so I keep it turned off during the summer. Setting up an attractant (light?) at another location away from the pups to concentrate them and then kill them at that location could be a good tactic.

Yeah, gotta be careful with poisons on edibles and the environment.

Good luck and get back to us if you find a solution.

sputinc7

Spectracide will get them good in grub form and it sounds like a bug zapper will work for adults.

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If you lose your head and give up, you neither live nor win.

https://sputinc7.wixsite.com/covwc

Varieties I supposedly bought: Manzano, Cavendish, Blue Java, Sweetheart, and Gros Michel.
What it seems I actually have: Brazilian, Cavendish, Namwah, Dwarf Red, Gros Michel, Pisang Ceylon, Veinte Cohol and SH 3640, and American Goldfinger. FHIA 1, Paggi and FHIA 17... Always room for one more.

edwmax

For this time of the year, deleting any compost from the soil mix would remove the grubs food source. ... And mixing a little pesticide into the soil mix would be easy for new plants being potted and in the future for any plants that would be in pots this time of the year.



If you have these in the nursery, then adults and more are in the fields. Controlling the adult beetle will go along way on controlling the grubs too.

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Nicolas Naranja

Imidacloprid would be my recommendation. Also, there are some biological grub controls, https://www.ncbi.nlm.nih.gov/pubmed/14658514

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Some people go bananas, I went plantains.

Botanical_Bryce

In Florida sometimes palm weevils get down in the corms. I have had great luck using beneficial nematodes. I apply every spring and fall and no grubs.

louis14

Very interesting interaction indeed. I googled this immediately and it opens a fascinating world of new solutions. Heterorhabditis bacteriophora should do the job, I hope I may be able to trace them here.
Thanks for this brilliant information!