What's this infestation? On Thornless Honeylocust - Gleditsia triacanthos var. inermis.

[Low Altitude]

Hello All,

What might this infestation be?

The plants are established but juvenile thornless honeylocust - Gleditsia triacanthos var. inermis. The infestation is systemic and uniform. The plants live in indoor surroundings, warm (barely ever below 70ºF or above 85ºF) and dry (rel. humidity typically 40%, spiking with summer rains to 70% maybe, but only for hours at a time).

Thanks!

 

[Low Altitude]

Hmmm. Photo seemed not to load. Let's try again:

 

[cpp gardener]

Spider mites or thrips. If there is very fine webbing it’s spider mites. Try putting a piece of white paper under a leaf and give the leaf a sharp tap. If you see dust specks that move you have spider mites. If no webbing the specks are thrips. For thrips use a systemic insecticide, for mites use neem oil.

 

[Low Altitude]

CPP to the rescue, once again! Tks so much.

There's no web, no external brush-off dusty stuff, no visible mites – looked carefully and have experience with such on this very plant, so when the white spots started appearing with the spring growth a couple of weeks ago, I applied a good amount of systemic miticide granules, this stuff, per the manufacturer's instrux.

No sign of the little critters or their webs, but the white spots continued to proliferate. They are in the cell structure of the leaves.

So it looks like thrips, by your description, but doesn't respond to the miticide.

Curious.

Is it possible it is mites, that the miticide is preventing them maturing into the adult form where they walk around and spin webs, but they still spread in some earlier-stage morphology?

 

[cpp gardener]

Thrips are insects and miticides don't control them, but the miticide should kill all the stages.
Do you see any insects at all? Everything I can think of that would cause that damage is big and active enough that you should be able to see them.

 

[Low Altitude]

>>Blush!<< You are quite right, CPP – I wasn't looking hard enough. In my defense, it/they were harder to see than during previous infestations and there is less of it (more of the whites spots). Under 30X magnification, though...:

Spider mites indeed.

Maybe what's interesting is the effect of the miticide I've been using: relative to the progress of previous spider mite infectations on the same plant, it has reduced the proliferation of the mites themselves, but not eliminated it, but it has increased the spread of whatever the precursor stage is that gives rise to the white spots inside the leaves.

Net-out, though: the miticide doesn't work.

So now what? Presumably the soil is infested, which is why the plants keep getting re-infested (and drenching the soil with miticide granules scattered on top is ineffective).

So I guess the plant is a goner: throw it away, throw away the soil, and boil the pot in bleach before re-using it?

It's a shame.

 

[cpp gardener]

Imidacloprid isn't a very effective miticide (sorry I didn't check your link). Try using neem oil instead. If you can find a concentrated azadiractin, it works a little better. If you've already disposed of the plant there is no need to boil the pot, washing works just fine.

 

[Low Altitude]

Thanks very much, once again. Fortunately, I have more seeds – but I'll go looking for the _azadiractin_ before I plant'em! Much appreciated.

 

[Chuck]

Neem Oil is effective against mites IF the Neem is fresh. It has a short shelf life once opened, about 4-6 weeks. Spider mites have 5 life stages and some of these life stages can be more difficult to control than others. That is why one must have consecutive sprayings (a minimum of 3) to control every stage of the reproductive process. No mitacide i.e asadiractin will kill everything with one application when it comes to mites. When using Neem always mix up more than you will spray and use the excess as a soil drench.

 

[Low Altitude]

I have got some neem oil and been experimenting with it, but i should ask – since the instrux on the bottle don't cover using it systemically, absorbed by roots: when mixing the oil with water for that purpose, what proportions? How much in a given volume of water, a gallon or a litre?

This interesting: I have a fair few pot plants in close proximity to each other. It's reasonable to suppose that all of them have been in infestation contact with the poor old honey locusts that suffered so badly from the spider mites (per posts above). The good news is that the neem seems to have eradicated the infestation in the honey locusts – great.

Adjacent to the honey locusts are several other pot plants, including an umbrella plant, Shefflera arboricola, established (probably fifteen years old) and large (maybe three feet tall) and hitherto nearly indestructible. I've not seen any infestation on this guy like that on the honey locusts (where it was glaringly apparent, impossible to miss, ravaged the plants) – but I haven't been looking too carefully either.

Then, last week, I noticed that a fair few sproutings of new spring growth had browned, stunted and died. Curious – the plant has certainly not been short of water. So I took a closer look, with the magnifying glass. Guess what:

Tentative conclusion: the umbrella plant is not immune / impervious to spider mites, but its leaves are more robust and waxy than those of, say, the honey locusts – except when they're freshly growing, 'babies'.

So I've been putting neem oil into its water (watering by drench). The question again is, what strength to do the job and not overdo it?

Thanks as ever.

 

[Chuck]

I have got some neem oil and been experimenting with it, but i should ask – since the instrux on the bottle don't cover using it systemically, absorbed by roots: when mixing the oil with water for that purpose, what proportions? How much in a given volume of water, a gallon or a litre?

This interesting: I have a fair few pot plants in close proximity to each other. It's reasonable to suppose that all of them have been in infestation contact with the poor old honey locusts that suffered so badly from the spider mites (per posts above). The good news is that the neem seems to have eradicated the infestation in the honey locusts – great.

Adjacent to the honey locusts are several other pot plants, including an umbrella plant, Shefflera arboricola, established (probably fifteen years old) and large (maybe three feet tall) and hitherto nearly indestructible. I've not seen any infestation on this guy like that on the honey locusts (where it was glaringly apparent, impossible to miss, ravaged the plants) – but I haven't been looking too carefully either.

Then, last week, I noticed that a fair few sproutings of new spring growth had browned, stunted and died. Curious – the plant has certainly not been short of water. So I took a closer look, with the magnifying glass. Guess what:

View attachment 97244

View attachment 97245

View attachment 97246

Tentative conclusion: the umbrella plant is not immune / impervious to spider mites, but its leaves are more robust and waxy than those of, say, the honey locusts – except when they're freshly growing, 'babies'.

So I've been putting neem oil into its water (watering by drench). The question again is, what strength to do the job and not overdo it?

Thanks as ever.

2 oz Neem per gallon of water for both spray and drench with a little bit of dish soap added for spray.
Remember that to kill spider mites you must disrupt their reproductive cycle and that takes at least 3 sprayings about 4 days apart. Only spray in late evenings and remember also that the more often a neem bottle is opened the shorter its' shelf life becomes.

 

[Low Altitude]

2 oz Neem per gallon of water for both spray and drench with a little bit of dish soap added for spray.
Remember that to kill spider mites you must disrupt their reproductive cycle and that takes at least 3 sprayings about 4 days apart. Only spray in late evenings and remember also that the more often a neem bottle is opened the shorter its' shelf life becomes.

So about a tablespoon in a 1-litre soda pop bottle. Wow – that concentrated – for root absorption? I'm not thinking about spraying (yet). Given that it's so oily, it won't clog root pores at that concentration? Just asking, sorry.

 

[Chuck]

So about a tablespoon in a 1-litre soda pop bottle. Wow – that concentrated – for root absorption? I'm not thinking about spraying (yet). Given that it's so oily, it won't clog root pores at that concentration? Just asking, sorry.

That is correct. And no, it will not clog root pores. Neem Oil has a natural chemical in it called azadirachtin that is absorbed into the plant but there isn't a lot of this chemical present and this makes the systemic approach to killing insects limited. Neem is not a great systemic insecticide but it is just about all we organic people have. Neem is much more effective as a soil drench than as a systemic insecticide.

 

[vegiokragrapevibrant]

From the pic you shared, it looks like your young thornless honeylocust plants are dealing with some sort of infestation. Now, I'm no expert, but based on what you described, it seems like the infestation is spreading throughout the entire plants in a consistent way. These indoor buddies of yours seem to be chillin' in warm and dry conditions. Hopefully, you can figure out what's going on and help those plants bounce back real soon!

 

[Low Altitude]

From the pic you shared, it looks like your young thornless honeylocust plants are dealing with some sort of infestation. Now, I'm no expert, but based on what you described, it seems like the infestation is spreading throughout the entire plants in a consistent way. These indoor buddies of yours seem to be chillin' in warm and dry conditions. Hopefully, you can figure out what's going on and help those plants bounce back real soon!

Well, there's only one question then, don't you think? Do you know what it is?