bacillus thuringiensis
 

Hello all
I've found a supplier who will ship a product containing bacillus thuringiensis to me here in The Canaries.
I want to try it on my citrus trees in an effort to control Citrus Leaf Miner - the little bast*rds have decimated my trees for the last 2 years.
I've tried Neem oil and other pesticides to no avail. I've even sprayed the trees with the most obnoxious aftershave I could buy cheaply - it was meant to confuse the moths - all it did was make me stink, even after a couple of showers! I can't keep up with squashing them by hand.
So, my question is, has anyone used bacillus thuringiensis and can give me some advice?
Do I just spray once and that is it for ever? Or do I need to spray each season, or every month?

Hopefully details will be on the product when it arrives - I couldn't read the pic online - but I'd like to hear of anyone's experience of using it while I'm waiting.
Thanks

It is the go-to product for all sorts of insect larvae. It doesn't touch the adults, is harmless to humans and pets. It gives the caterpillars and other wormy-things a tummy ache... they stop feeding and die. So keep it away from your milkweed... The instructions should indicate how often, it doesn't need to hit the "targets", but when it's on whatever they are feeding on - leaves, fruit, etc. it kills them. It is not systemic. Since you don't get significant rain during the growing season, you probably don't need it too frequently since it won't wash off unless you water the foliage.

Does it work against leaf miners?

Worth a try... I don't know how specific it is with respect to the larvae of various species, but basically it is the only thing that targets that destructive stage of life of insects. I got it in a hose-end sprayer (Home Depot) to anoint my avocado tree when I had a caterpillar attack and it did the job. Since it isn't toxic to people at all, approved for organic gardening, what do you have to lose other than the price of the product to try?

You can read about the effectiveness of BT against leaf miners here: [PDF] Efficacy of Bacillus thuringiensis against Phyllocnistis citrella (Lepidoptera: Phyllocnistidae). | Semantic Scholar

Don’t know if you can get them where you are, but people around here use hormone traps with good success if you replace them often enough.

Our LM pressure may be lower than yours since we usually only worry about LM damage on very young trees. Established trees typically have enough foliage that the damage done to leaves during peak LM season isn’t really an issue. If the Bt doesn’t work, spinosad would be next on my list.

Use soft water with a pH a little above 7 with both of these pesticides. Hard water and water with an acidic pH will reduce the effectiveness of both.

Thank you so much to everyone who has responded!

I got a bit overwhelmed reading some of Semantic Scholar articles but am encouraged that this might be the answer for me.

I can't get the traps here, or Spinosad.

I have 8 assorted citrus trees, all about 2 years old, and hardly an untouched leaf amongst them :(

Unless the info on the product says otherwise my plan is to give an initial spay, repeat it if we ever get any rain, repeat it when I get a flush of new growth.

I normally only spray the leaves with water when we have had a calima, to give them a freshen up - I'll think carefully before doing this in future.

My water is around 5.5pH at the moment - I have pH plus liquid that I use for the swimming pool - can I use that or is there something more natural that would be preferable?

Once again, thank you so much; you wonderful bunch of helpful and knowledgeable people :bowing

What is in the ph-plus product? If it is sodium bicarbonate or sodium-anything), sodium is undesirable. Calcium carbonate would be better as a pH raiser. Pretty insoluble at higher concentrations, but at low concentrations (especially since your water is pretty acidic) probably would do the job. Or something with potassium. I am sure one of our more "chemically savvy" members would have a better idea, again depending on what is in you pool product, may be fine.

Just had a look - it's Sodium something :(

For calcium carbonate, look for limestone or dolomite lime. At pH 5.5 some will dissolve. Worth seeing what it does. Or, you can actually get powdered calcium carbonate... several sources came up when I googled it. That's the active ingredient in many antacids... so certainly non-toxic but you'd want to use a version without the flavorings.

I've got Chelated Calcium:

https://i.imgur.com/l01SxZJ.jpg

https://i.imgur.com/3QJC34l.jpg

Could I use that do you think?

Not likely to do what you want to do, which is to raise the pH. I think you really want something inorganic - strong base tied to weak acid. (corrected, had it backwards)You could see what that chelated Ca does to pH of some water, but the main point of that one is to tie up the calcium so it doesn't precipitate in the presence of sulfate, etc. So depending on how it is bound, the calcium may not be doing what you want.

I think I'll pH test several different bottled waters tomorrow, if one is 7 or above that may be the way to go ....

Thank you so much for all your help.

Even close to neutral should be fine. I had never thought about it until ES brought it up... The stuff comes in a sprayer already mixed, to be connected to a hose. But my tap water is around pH 7.8 because it's loaded with calcium. I do also have some BT concentrate that I can mix up in small quantities. The stuff works. (Spinosad is just a synthetic version of the active "ingredient", I think the real product with actual bacilli works better.)

Spinosad isn’t related to Bt. It’s similar in that it’s a naturally derived biological substance, but they’re not the same thing. Bt has residual effectiveness for a couple days and spinosad can remain effective for a few weeks after application. Bt is highly effective for the target pests and is more pollinator-safe compared to spinosad, which will kill beneficials when it’s wet.

A thought with regard to pH adjustment... a lot depends on what is making the water so acidic. If it's organic acids (like from decaying organic matter) it may not take much because those tend to be pretty weak. If something else, then it may be more resistant. As dry as your climate is, probably not organic... volcanic, sulfur for instance?

It was Dimples who brought up the pH issue.

Oops. Sorry

All desalinated water on our island

Surprises me... I would expect desal water to be on the alkaline side. But what do I know?

Desalination is done through reverse osmosis, which yields very soft (mineral-free) water. Most municipalities add alkaline minerals to combat the sour taste of RO (carbonic acid from CO2 absorption) and to protect pipes, valves, etc.

I read it kills butterfly larvae so be careful when using it if you have butterfly larvae anywhere in the vicinity.

Yes, it kills caterpillars. That is why I mentioned to keep it away from the milkweed. Like any remedy, it needs to be used surgically... spray the affected plant, not the whole world.

I cant even imagine the plight of trying to grow these where you are at.

we take our great tap water for granted to be sure. still cant drink it but it wont kill ya plants :)

It's interesting RJ. When I first started with orchids (mass market hybrid phals) I was very concerned about our water and it's possible effect on the orchids. Ray and ES and others really helped me - I can't get a report from our water supplier. Adding a reg dose of Cal/Mag has made a big difference and I didn't have to swap to bottled water.

Everything in the garden now gets mineral supplements as well.

And we drink our tap water with no ill effects!

everyone I know or knew or who was always used cal/mag + products.

the peters excel cal/mag was my choice but I cant find it readily available. last bag I found the shipping cost more than the bag of fertilizer.

yes cal mag supplement is good stuff for all things orchids :)

I don't need a cal/mag supplement because there's so much in our tap water. I mix it with collected rain, about 20% tap water. When I add MSU fertilizer for pure water to that, or a typical 20-20-20 with micronutrients, I get pH around 6.0.

The product (Cordalene) arrived today (just 10 days, amazingly quick for us!). I've got in a supply of bottled water with a pH of 7-8. Gonna buy a new pressure sprayer tomorrow which will be kept solely for this.
Instructions say to thoroughly wet all leaf surfaces every 7 days for 3 weeks.
Fingers crossed for speedy results.