Did you use dish soap that is real soap or detergent? Most dish soaps are detergents, not soap and therefore will not work against aphids... unfortunately. I never had mine turn black, from the dirt? I think a spray of water works best. Sometimes I'm savage with my plants spraying them with water to spray off the aphids. Good luck.
Pam

have you recently done a foliar feeding with epsom salt? as I understand it, epsom + neem oil will react to form a black sticky mess that will pretty much kill the plants.

let's hope this isn't what happened.

Why soap AND oil. Pick one or the other. Like Pam said, do not use dish soap. You need a REAL soap, like castile, fels naptha, etc.. Also, like she said, blasts of water is usually sufficient for aphids... you just have to be diligent every 3-4 days.

If you do use soap, do it in the evening and rinse the plants in the morning. Also, with ALL pesticides, do not spray when temps are above 80F or the sum of the temp and humidity is >140.

Commercial soaps are best since they're designed specifically for pests. But, if you're going to make a homemade one, this link you should read. Short, simple, and to the point. And doesn't steer you wrong to create a problem you have.

With oils, neem is probably best. But no need to mix the two. Once again follow the temperature guidelines.

Kevin

Here is a link that might be useful: homemade insecticidal soap recipe done right

I had limited luck using soaps and neem oil on my peppers/miracle berry bushes for aphids and scales. I realized I wasn't shaking the neem oil prior to mixing it last application, and was astonished to find after doing so (following the required mix amount) that all the scales that had been ravaging my miracle berries were gone the next day (imagine that, following ALL the instructions). I'm going to follow up with my peppers tonight but at least for me, neem oil (shaken!). Works wonders. Good luck!!!

Azamax. I fought aphids in several world wars and lost with almost every organic remedy on the internet. Azamax finally worked. Get it on Amazon real quick.
http://www.amazon.com/gp/product/B0032JYKGG/ref=wms_ohs_product?ie=UTF8&psc=1

I find where the ants live and spray that with chemical insecticides. With no ants to guard them the lady bugs eat the aphids.

If one needs non-organic methods/pesticides to fight aphids, his/her garden is seriously out of whack, imo.

Kevin

gro2can, I've had aphid problems here in zone 3, but never on outdoor peppers, even when heavily fertilized. Are you sure the aphids are at levels high enough to cause a problem, or are you just spotting the occasional aphid?

I get some aphids on my peppers, but they then attract ladybugs, jumping spiders and sometimes ants and wasps, so the outdoor aphids never have become a problem.

If you do have serious aphid problems, I'm not really sure what to suggest. A few aren't an issue, a serious infestation can get ugly.

Not sure how many plants you are dealing with but here in DC I have huge aphid problems in the Spring. The best thing I've found is squishing. Doesn't hurt anything else, seems to draw the ladybugs and larvae and gets afterwork stress out.

Does take a while to get over the ewiness factor.

Try sprinkling/dusting wood/charcoal ash on them, like you would Sevin dust.
Of course blasting off with water ( I use my garden sprayer ) remains another method. If I want to use chemicals, choose Neem Oil. It is a double edged sword : Pesticide and fungicide in one.

was using palmolive dish soap and oil. got recipe on line from some university in the u.s. sprayed on really hot day did not want aphids to spread tons of eggs. left overnight then washed with water since leaves were burning under sun. now lot of leaves turning black, buds dropping as well as flowers and formed peppers. all growth seemed to have stopped. going to give compost tea to try to revive. aphids all gone seem like. thx aki