Backyard Aquaponics
A place to discuss aquaponics

This is the second year I have had cucumbers in my AP and they did the same thing last year. I tried to be diligent about the cucumber beetles, checking and killing any I found daily, sprinkling DE, plastic yellow plates with tanglefoot on them (these never picked up a single one, lots of flies though), nothing kept them away. There were a few days I could pull a dozen or more cuc beetles off them, I would go home at lunch and kill some, kill more right after work, and again before the sun went down. lately it has been few and far in-between. They have moved on to my squash in the soil garden now as I have already lost what was in the AP…

I am at a loss, they still have great new growth, and are starting a few cucs even, but if it is like last year I will be able to harvest a few and all growth will stop…. So what is happening? Are the beetles/larva killing them? did they spread a disease? am I missing nutrients? Is there anything I can do to save them? I am really disappointed as I opted not to plant any in the soil garden this year after a request form my wife, she said the cucumbers we got from the AP last year where the best she had ever tasted.

Also I have lost 1 of my watermelon, all my cantaloupe, and my squash that is in the AP will not make it to the end of the week. Everything in the soil garden is doing well so I cant help but wonder what is the issue with the AP? Tomatoes, kale, eggplant, jalapenos, it is all very healthy in the AP the water test shows nothing out of the ordinary, PH maintains 6-6.5, plenty of nitrates, I add a bit of maxicrop+ iron every now and then. The fish are happy. I just cant figure it out.

...maybe I shouldn't write a book when asking a question! LOL

If it's the oldest leaves that are worst affected and they start by yellowing between the veins and around the edge of the leaves, then the edges die off and appear as though the leaves have fertiliser burn... then I would suggest it's possibly a Potassium deficiency... very common in AP systems heavily planted with fruiting plants.

As your pH is in the low 6's you could try adding Potassium bicarbonate at 1 x level teaspoon per 1000L of water. It will raise your pH slightly, so it's best to dissolve it in a bucket of the system water then add it back into the system in 3-4 stages over a couple of hours. Potassium bicarbonate is commonly used to raise and buffer the pH in AP systems.

I just thought that that was how cucumber plants acted...

Thank you Mr Damage. I just ordered some Potassium bicarbonate, it should be here Friday.