Backyard Aquaponics
A place to discuss aquaponics

I've chronically had this deficiency that only appears in basil and lettuce greens. It starts with small necrotic spots on mature leaves and not during seedling growth, but quickly as harvest-size develops. It ends up taking the whole plant.

Additionally it seems to be worst at the inlet end of the bed and least damaging (but invariably manifesting) towards the siphon end. I have ornamentals of several years sitting right next to the worst-affected that have never had a problem. Any thoughts?

Here it is on a mature plant, new growth not yet affected.


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Thrips! You can see them on the edge of the leaf in the last picture...

Safer soap can help - made of potassium fatty salts. Just make sure to spray the undersides as well as the top of the leaves. And try to avoid over spray (dripping into your grow bed) since too much can harm your fish. You will need to hit those plants hard with repeated doses as thrips are a pain to get rid of. Also, spray them before lights or sun hit the leaves and/or right before the lights/sun turn off or set so you don't get leaf burn.

Good grief, really? I must have a whopper going after all this time. How about neem?

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And went wouldn't they be affecting the ornamentals?

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I was going to say that looks like an infestation more than a deficiency, yeah. You definitely have something tiny and white all over those leaves and bigger ones (adults?) visible in some spots, easiest to see on the young leaf in the top left quadrant of the last pic - I'd guess they're not on the ornamentals because they don't find them nearly as tasty / delicate.

Neem oil should work the same as a soap spray, blue sticky traps apparently attract the adults, and there are also natural predator bugs you can get: https://www.planetnatural.com/pest-prob ... s-control/

Yep, totally thrips on closer examination. I feel pretty stupid! I pulled all the affected plants.

How to treat the media and environment?

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In your place I'd probably soap spray all the remaining plants (covering the media so the soap doesn't get into your system water), then get some blue sticky traps so it'll be obvious if they're coming back. Check the sticky traps regularly, and when/if you see adults on there, time to soap-bomb your plants again or possibly get some predators.