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New-ish gardener here! This year I have planted 5 varieties of peppers in a brand new raised bed in central Arkansas (zone 7b). Fill for the raised bed is 100% compost purchased from a local plant store, with no amendments or additions.

Initially all of the peppers saw slow growth through the cooler, wetter weeks after transplanting, but as it has warmed up most of them have grown quickly. At first 2 of the plants showed signs of strange growth, including new leaves curling, thickening, becoming harder, darkening and areas of new growth looking strange and stunted. Because of the presence of these symptoms only on new growth, I assumed a calcium deficiency. (google image results for "pepper plant calcium deficiency" show at least one result that looks like my plants, but the comments were inconclusive). Several posts here have suggested that ongoing pest damage could cause this, but I have seen very few pests and have preemptively applied neem oil on a couple of occasions.

In the last few weeks, new growth on some of the surrounding plants has started to show some of the same symptoms and now I am not so sure what could be going wrong here. I'm starting to think that it could be one of the following:

  1. Disease (virus, maybe? transmitted between plants via pest)
  2. Deficiency of some nutrient (peppers are growing in compost with no soil mixed in)
  3. Toxicity of some nutrient (I have no idea what the nutrient balance of the compost is)
  4. Presence of herbicide in compost (I don't know the source of the compost)
  5. Environmental factors (Maybe overwatering. Compost retains significant moisture)

I'm trying to determine if any of the above causes are an obvious cause of these symptoms.

In addition, These plants are planted within 5-10 feet of a bed of tomatoes in similar planting conditions, some of which are showing leaf curl which does not resemble this, and a potted ground cherry plant in store-bought potting soil does have similar symptoms.

I've attached some images that should show the affected area of a couple of the plants, as well as a previously healthy plant that is now affected. I can provide any additional photos, including ones of surrounding plants, to help diagnose this.

patient zeropreviously healthy plant Closeup of previously healthy plant

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  • What kind of conpost?
    – Bamboo
    Jun 16 '20 at 23:46
  • @Bamboo, It's a municipal compost, I believe. I bought it from a garden center. It has lots of organic matter, as well as the occasional piece of random litter. Jun 17 '20 at 15:28
  • Let me know if you find a solution. I have been growing hot peppers for years in Ohio and all of mine have this exact issue except Jamaican Yellow Scotch Bonnets. I usually have the best looking plants of anyone and I use manuer solids, clay, balanced NPK fertilizer and pre season boost soil with 100%N Urea Nitrate and pure calcium. They all displayed this at the exact same time and I have a pretty big garden so I am thinking it is environmental somehow not the soil. We had a lot of rain do I am thinking it is root rot or mold in the soil. Just a guess. Jul 26 at 2:29
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If you filled the bed completely using only municipal compost with no soil, that might be the problem. Composted materials of this type are meant for mulching or digging into garden soil; they are not usually suitable for use as a planting medium, especially not in a contained area. If your raised bed is open at the bottom and sitting directly on soil,that's not quite so contained as a raised bed on legs - not sure which you've got, but even so, there is no soil in the raised bed, only the compost. You could try checking the source to see if it's been produced using a hot, aerobic method, which would mean it is suitable for use as a planting medium, but more usually, these are not produced in that way.

The other possibility is there is some contamination from pesticides (usually herbicides) of some sort; this could be present in the compost, or could be caused by spray drift from you or someone else spraying some sort of pesticide nearby. Note that composted materials meant for soil conditioning purposes do not usually cause problems when mixed in with soil in open ground, though some horse manure can sometimes be contaminated with a particular herbicide.

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  • I never fail to add dirt to my compost, or 40% sand to silty soil. Plants need drainage an micro-nutrients. Your initial slow growth may have come from too much nitrogen in the compost. Peppers are sensitive to that. I lost a whole month's growth to too much N one year. Darn plants just sat there. At the plant size you have, there's a good chance they'll recover. Feb 19 at 21:42
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My son got couple yards ( he is young and has a truck) of great looking, free mulched soil from raised beds at an apartment complex that was removing the beds. He put it in his own raised beds with results similar to yours. LATER he found out the apartment complex had been using herbicide on the raised beds because the residents were not using them and they were full of weeds . After 3 years he was able to grow in the beds. Easy to imagine you encountered some variation of this scenario.

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  • After several years of similar issues with my pepper and tomato plants, I narrowed it down to herbicide damage. Either in the grass clippings I use for mulch or the fine mist from spraying the lawn turns into vapor. I now cover my plants with blankets when spraying and have three years with zero damage.
    – Evil Elf
    Jul 27 at 11:42

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