I think it is leaf cutter ants based on my web research, which is fairly discouraging as far as eradication success stories. (Diatomaceous earth, laundry detergent-?, and Jackbean are what I found to try but no one endorses these enthusiastically.)
Can't see any pests or even ant hills, but the leaves are classic munch-bitten and the tree is rapidly declining. Please tell me what works and what doesn't.
Organic is best but I would consider (mildly) toxic to save this tree!!
Thanks, and HURRY!
Gina
Something is eating my tamarind to death
I have been mildly successful using horticultural grade diatomaceous earth to deter carpenter ants. It is not perfect but it is certainly harmless and appears to work by cutting the bodies of insects when they land on or in it.
http://www.hort.purdue.edu/newcrop/morton/tamarind.html#Pests and Diseases
sorry about your tamarind, they're beautiful trees! the article is a lot of reading but you can jump staright to the pests and diseases. unfortunately, i didnt see anything about controls and a lot of pests mentioned are in India.
Gina, a picture of the leaf damage would be helpful. Have you actually seen the ants cutting the leaves?
You also might have Sri Lanka weevils - they eat the leaves in a similar way. It's easy to find out if you have them by just spreading something dark-colored under a branch and shaking the branch vigorously. They will fall off onto the dark surface (a tarp, or a dark umbrella works) The weevils are white and up to 1/4in. long with a hard shell, and sometimes have gray dots on their backs. It's also really easy to see them at night with a flashlight. Look under the leaves.
Unfortunately, as with the ants, there's not much that works on these weevils, even noxious chemicals aren't dependable. So mechanical removal - shaking the tree, collecting the weevils when they drop off, and crushing them or dropping into soapy water slows them down substantially. The key is to break their life cycle - the adults live on the undersides of the leaves, mate then they drop to the ground and lay their eggs in the ground. Once the larvae metamorphose, they climb back up out of the soil onto the host plant again.
I've had a few on my rose bushes, and have kept damage under control by hand picking the bugs (with gloves on, although they don't bite or sting). I'll see if I can get a picture of one.
It seems so surprising that something is damaging your Tamarind, they're what I always considered a "cast iron" plant. Mine have never had anything attack them (I've got about 40 to 50 of them, up to about 6 metres tall). Check the plant at night as well, a lot of leaf munchers are active then. But you need to identify what exactly is doing it. If it is ants you have to destroy the colony. Probably the most environmentally "friendly" way is to dig up the nest and pour boiling water over it. You might have to do that a number of times. But that's not to say another colony might not move in some time later. Good luck with it, they're a very beautiful tree (when healthy looking).
i was going to suggest weevils too. depending on the way (pattern) in which the leaf is eaten would help determine which kind it might be. i have the little leaf notcher weevils here and they love anything with a "mimosa like" leaf. of course, they love other things too. trying to plant plants they don't like is a constant here. another thing i've found is that on certain plants, they don't just notch leaves, they scrape the new growth at the tops of stems causing eventual death to the plant unless it is a huge, totally established plant/tree, etc.
i've had excellent results using castile soap and water as a spray and alternating with spinosad spray. that is to say, they are under control in some areas.......sigh.