Hello all!
I have a sweet potato plant that seems like it's dying. (maybe because it's winter?) It was really flourishing all spring and summer (even with recurring spider mites), but now the vines are almost completely without leaves, there is minimal new growth, and there are tiny flies - if they're not fruit flies, they really resemble fruit flies - and a lot of them - flying all around it. They seem to hang out down around the soil too - it seems like they're feeding on something in the soil. The sweet potato that the plant grew out of is still there in the soil - would they feed on that? Also, my neighbor graciously cared for the plant while I was away for 2 wks in November. The plant wasn't looking so hot, so he decided to "feed" it with his green energy drink - one of those all-natural green fruit juice drinks like an Odwalla Superfood or something of that nature. I suspect that the green drink attracted the bugs, but would it still be attracting them now, 2 months later? Would the green drink harm the plant? I can't tell if the bugs are harming the plant, or just congregating around it. Should I use a pesticide? Help!

I beleve those are called fungus gnats, they're really a pain aren't they? They're so annoygin, not too sure what the green liquid is, but seeing as you have those gnats, I would advise you to repot, remove all the soil by rinsing the roots, and toss the oil soil out (I wouldn't use soil that had fungus gnats in them, they come from a fungus in the soil hence the name) Give the plants a bit of time to settle down after the transplant.repotting and I'm pretty sure they'll perk right up

If they have bright red eyes, they're fruit flies. Otherwise my guess would be, as kennyso, fungus gnats. They're more of a nuisance to people than the plants, and at worst can cause minor root damage and harm to young plants.

Typically fungus gnats are a result of overwatering, and feed on the decaying organic material in the soil. To get rid of them wait until the soil is almost completely dry before watering again. This should be made the plants normal watering cycle.

From my experience, they're probably not the reason for the decline in your plant's health.

Sweet potato dies off thru winter. Dig them up and eat them. Plant fresh tubers or runners in spring.

sounds like fungus gnats... here is an article i wrote on them.

fungus gnats

I have found for control beneficial nematodes work the best.