Backyard Aquaponics
A place to discuss aquaponics

Hi

I recently planted out my tomato seedlings. They were perfectly healthy when I transplanted them into my system. A week later they started showing these spots. First on the older leaves so I chopped them off. Then it started showing up on the new leaves as well. They also don't show any further growth. The same seedlings that I planted out in my wicking beds (not connected to my AP system) are doing fine and they are almost three times the size and looking very healthy. At the same time that these spots showed up on the tomato plants it also started showing on some of my lettuce which has been doing really well long before the spots started showing. All other plants seem to be doing good with no effect on them. I did add chelated iron to my system the week before the spots started showing and I think I added too much, but don't know if this is the cause because my fish are still happy and the plants only take what they need I think?

Any help appreciated

Two different things going on I think. The lettuce looks like it's been rained on and then had some tissue collapse, possibly because of bacteria or fungus in those areas.

The tomato looks like it may have spider mites although there could be some water damage there as well. What's the air and water temp like there?

Pics of the whole plant and growing area would be helpful also

Hi Scotty

Both these veg are at the edges of the roof so if the rain comes in at an angle and they definitely get rained on.
The temperature at the moment here in Shanghai ranges from 10 - 25*C. Water temperature should be around 20*C. I has been raining on and off the past month.

When you say water damage, do you mean spraying the plants on sunny days with water?

Thanks for your reply.
Here are some more images....

Your plants look good overall



No that's not what I mean. Poor statement on my part. The water really didn't do the damage but it may have provided the environment needed for another organism to grow and penetrate the leaf. This reminds me of alternaria lesions on curcurbits but I don't know for certain what is causing the lesions on the tomatoes you have. My advice would be to remove the affected leaves and the conditions that favor them getting wet if possible. Make sure the leaves have a chance to dry out before nightfall if you spray. It sounds a bit cool for tomatoes right now so that's a contributing factor I think.

There is a remote possibility that these are showing a magnesium deficiency but it doesn't look quite like I'd expect and if you're not seeing it in any other plants around this, then I think it's unlikely.

I'm pretty sure you've got spider mites on 1951, 1964, 1965, and 1966 images. I think they're all the same plant. They're tiny enough you might need a magnifying glass. You can put some white paper under the branch and give it a shake, they're easier to see against the paper .

edit: with the dark borders around the lesions could also be septoria leaf spot and instead of being spider mites those could be pycnidia fruiting bodies of the fungus. I kind of don't think so but you'll find out - the mites move.

Hi Scotty

I've never added magnesium to the system, will buy some epsom salt and add some anyway.
I will remove these plants, don't want the mites to spread to other plants.
I've got a new batch of tomato seedlings which will be better to plant now cause spring started now here in Shanghai.

Thanks for all the advice.

You might not need the Magnesium but if you do -

Epsom Salts - MgSO4 - A teaspoon of Epsom salts per 1000L or a smaller foliar dose 375g to 20 litres - from the product label Faulding Epsom Salts. 1 tsp per gallon for spray or 1 T per gallon in soil drench (for regular gardening). Do not over apply and don't use on bright sunny days - this can cause leaf scorch.