SOIL New Grower Believe I Have My First Serious Issue Need Advice

[TheKieftan]

This is my first indoor grow after my first outdoor grow last summer I only bought 1 clone and a pack of seeds to try my hand at indoor I have limited space so decided on 4 plants 1 mango kush clone 2 banana mango from good seed and a chocolate from bag seed right away one banana mango started to shine while the mango kush thrived sadly the other banana mango and chocolope we’re struggling significantly to the point they needed support to stand but were still getting new growth though slowly today I decided to kill them if they didn’t stand after removing support 1 did the banana mango runt but the chocolope fell so before killing I decided to check the roots as I turned it over I noticed right away small black objects on the bottom of the leaves after light scraping 1 fell off it’s very hard I immediately checked my other 3 plants and saw 2 very very small black spots on the other struggling plant my questions are what is going on and should I be worried about my 2 healthy plants below is a picture of the black dots

[Ace1973]

Aphids, use neem oil on the branches and diotamaceous earth on the soil.

[9fingerleafs]

Yeah root aphids. Resilient bastards. They fly. They crawl. They swim. Gotta attack from all fronts. Sticky traps. Spraying. Drenching with peroxide, mulching, there are predatory bacteria but it’s hard to get your hands on.

[Ace1973]

I use dawn and water, works well, fly strips, sticky traps, I have used peroxide before as well, it works. BTI, also works, google it, you will find it.

[Rwise]

I use ISO 50/50 with water and spray em every other day for several treatments.
Ladybugs work best.

[Anansi]

When spraying your plants, be sure to do so just before lights out. Under bright lights, the liquid can burn your leaves. I learned this the hard way with neem oil. I did more damage than the aphids.