Mildew on soil of Lowryder plant. Scrapping plant as precautionary measure?

I was checking on my grow and I saw a bit of white mildew or mold on the top layer of soil of my Lowryder plant. Humidity is never over 40% in the tent but the plant itself was in damp soil and isn't using much water. It's around day 65 but isn't very mature. I have many other plants in various stages of growth and I'm just going to scrap this plant and hang it. I'm sure it's awful. I'll make some sort of extract I suppose or see if it's at all smokable. I'm being extremely cautious. I have around 16 pots in a 3 x 3 tent and it's extremely crowded.

I don't want to risk my future harvests over a shitty Lowryder plant.

Is there some sort of preventative measure I can take against future things like this?

could it be that you just saw roots poking out of the soil? They usually have a thick moldy layer on them. is it bright white?

anyway if it mold you should spray them with neem oil, this will be good prevention i think

I went and pulled it. it was actually worse than I thought it was. I've got 15 other autos going ranging from 5 days old to around a month. It was white mold or mildew and it had a bit of an odor to it. So did the bottom of the pot when I pulled out the rootmass. I figure I'll let it hang and such and if it's smokable I'll trim it and if not I'll make some hash oil or something. Smells like weed. Easily a few weeks immature.

water less then...mold and mildew won't grow in dry areas...if you are keeping your soil moist all the time you are going to have mold/mildew issues. If the humidity is high you'll also have issues.

I hadn't really watered it in a few days. My other plants are much younger and use more water. It was an unhealthy plant languishing in the corner. I figured since it came from a feminized seed, had some mildew, and was experiencing a lot of stress it was only a matter of time before it hermied or fucked up my other plants in some fashion. I wasn't willing to take the risk for a haggard lowryder. Maybe I can make some hash oil out of the lower buds and possibly smoke the others. Bollocks.