It appears you have been trimming the dead stuff off the pepper plants? If you don't do the dead leaves stay on the plant? If so I would lean toward it being Verticillium dahliae as the culprit.

Are they being overwatered? Peppers do not like to have wet roots. I have killed many a plants from overwatering.

Maybe get your soil checked as well. Also cut down on fertilizing. Once a week is too much IMO.

Jamie

As a rule I don't like to fertilize if plants are not growing well. As a general rule fertilizing unhappy plants just makes them more unhappy unless there is a clear cut identifiable deficiency.

I don't know if this is of any help, but all my peppers are in pots, also Tom grows his in pots... mine do OK and some are several years old, but they go in the shade in the summer and I feed them MG, aweak solution I keep in a milk-jug and go around to all the potted stuff weekly... also they get pretty dry between waterings... sally

Have you checked closely - w/ a magnifying lens, if possible? I'm guessing it's insects - perhaps chili thrips or mites. I have similar probs, & FWIW it seems a seasonal issue. I had better luck w/ Early winter/spring started peppers.

I appreciate all the ideas, guys!

I'll do some diagnostics on the failing plants. Some are so far gone that they'll have to come out, so slicing open the stems should be a quick check for verticillium. I'll also put the leaves under a glass and look for thrips (though a "white paper" test revealed nothing).

Meanwhile, I've got a few extra containers and plenty of Al's Mix, so I'll stop off at the local big box and pick up a few bell plants. If I throw a few in containers and a few back in the raised beds (unless the peppers show signs of verticillium, in which case I just have to keep them out of that soil), and mix up the water/fert, I can experiment and see which ones do better.

Alan

My two cents. To me it looks like too much nitrogen. Peppers do not like a lot of nitrogen and mine absolutely hate foliar feeding.

Sounds like your soil is rich, your mulch is decaying (and releasing nitro) and you are giving them a nitrogen bath weekly. You are loving them to death.

FWIW, sucking insects can transmit viruses, so it can be a 1,2 punch...

Again, thanks for all the advice and suggestions.

I pulled one of the failing plants and sliced open the stem. There were no signs of verticillium - the stem was clear of blockage, and the roots didn't show any abnormalities. I looked at the leaves under a strong light with a magnifying glass, and no signs of mites.

I swung by the local big box and picked up a pair of green bells. One went into a container of Al's mix, the other went into the site of the former failed plant. I'll cut back on the fertilization and the watering of both, and see how they do over the next couple of weeks.

Alan