Help! My Aubergines Are In Trouble.

[Peanut]

Three is something odd going on with all my aubergine plants. They are in a mix of miracle grow peat free and manure and have so far had one feed of tomato food last Monday.
I grew them in the same compost last year and I think I added manure too, so I am stumped as to what is going on with them, but they are clearly not happy despite being covered in developing fruits and flowers.

Any thoughts as to what is wrong? I can't see any bugs, or webbing or anything on them.

[Jungle Jane]

Spider mite,there’s webbing here in the photo below,spray when the suns gone down with garlic water & a dot of wash up liquid or hand soap.

[Jungle Jane]

When you see a ladybird,take him/her to your aubergine but don’t spray if there’s ladybirds

[Penellype]

Gosh you have good eyesight Jungle Jane ! My thought was spider mite too, given the hot, dry weather we have had. I get it on indoor tomatoes sometimes. Misting with plain water will help as they prefer to be dry, also you could try wiping the webs off with tissue, which will remove some of the mites.

[smallblueplanet]

Okay maybe here's a clue to the cause:

Humidity:

• Aubergines thrive in humid conditions, which can be achieved by misting the plants regularly with tepid water, especially during hot weather.
• Placing containers of water around the plants can also help increase humidity.
• Adequate ventilation is also important to prevent fungal diseases that can thrive in humid environments.

Red spider mites thrive in warm, dry conditions, commonly found in greenhouses, conservatories, and on houseplants. They are particularly problematic during the spring and summer months, especially in hot, dry weather.

Of course one of the drawbacks of a humid greenhouse is that tomatoes like it drier:

• Ideal Humidity Range:
  Tomato plants thrive when humidity is maintained between 60-70%.
• High Humidity Risks:
  High humidity, especially when combined with inadequate ventilation, can create an environment that encourages fungal diseases like blight and mildew.

[Peanut]

You know what, I took these photos yesterday evening whilst watering the greenhouse and didn't have my glasses on! I initially thought spider mite, but couldn't see a thing on them!

There a lots of ladybirds and hoverflies in the greenhouse so I better not do any spraying.

I'll get some trays of water in there and give the plants a misting and a wipe and a squish.

I'll also get some more glasses so I can have a pair on when I'm outside (I am still in denial that I can't see anything close up without them )

Thanks everyone, you're all fab!

[Peanut]

I am also going to move the aubergines outside for a few days with a sign above them reading, "free all you can eat spider mite party, ". hopefully that will get more ladybirds etc on the

At the moment nothing else, peppers, tomatoes or cucumbers appear to be infested., though I had better go and check again with my glasses on...

[ameno]

Sadly ladybirds usually won't eat spider mites. The mites are probably too small for them to bother with (they're less than a tenth the size of aphids).

[Peanut]

Sadly ladybirds usually won't eat spider mites. The mites are probably too small for them to bother with (they're less than a tenth the size of aphids).

Oh b**ger

[Trouvere]

I appreciate the reluctance to risk other invertebrates with use of a pesticide spray, but this would bruteforce deal with the problem. Are the aubergines in pots? Could they be moved somewhere indoors to be treated, and returned outside once the insecticide is gone? I think pyrethrins break down quite rapidly, for example.

The usual biological control method is to purchase some predatory mites like Phytoseiulus, but these are expensive and frankly they're unlikely to get ahead of the Tetranychus since even under optimal conditions they reproduce less rapidly.

There's a third experimental possibility. Tetranychus mites have lost the genes for the arthropod innate immune system. If they come into contact with bacteria, they tend to die, like Martians in War of the Worlds. You could thoroughly dip the plants into a live compost tea, and hope that some bacteria go to town on the mites. Or, if you should have access to pure bacterial cultures somehow, then Bacillus species are said to be effective.

[Snoop Puss]

^That is very interesting, Trouvere. Bacillus thuringiensis is readily available for gardeners. Sounds like it would be worth a try, is that right?

[ChingfordHarry]

^That is very interesting, Trouvere. Bacillus thuringiensis is readily available for gardeners. Sounds like it would be worth a try, is that right?

I think that any BT species available for home use would be very unlikely to have any activity against spider mites - the genetically engineered crops containing BT toxin genes were mostly designed to be of use against Lepidoptera - principally moths.

This is quite recent and may be relevant -

https://blog.entomologist.net/is-bac...der-mites.html

[Snoop Puss]

That was very useful, Harry. Thanks.

[Trouvere]

Yeah, Harry's right. The BT toxin is pretty specific to Lepidoptera. It is possible that B. thuringiensis itself would infect and kill spider mites, simply because they're vulnerable to almost any bacterium, but the toxin itself would not be a relevant factor. The B. subtilis in authentic Japanese natto (fermented soy bean) might be worth a try! In the studies I've read, the most effective organism for killing spider mites was B. megaterium. That leads to a strange image - a Tetranychus mite might be 0.4 mm long, and some B. megaterium cells can be exceptionally 0.1 mm long (though very much thinner)...infection doesn't seem quite the right word for what happens to a mite in that situation.

[smallblueplanet]

All that for a few aubergines? Just mist them and accept you'll lose a few?