Question

Needles dying   Ok...I'll spare you the story of why these pine seedlings are so important to me, but just trust they're really important to my mental health. :)

I propogated them from the orignial tree cones (Los Angeles) and have been planting the germinated sprouts every couple weeks for about 4 months now. In Miracle Grow seedling starter mix.

So I have them at all phases up to 4 months (1-10 inches)
I'm a city boy 43 years and have never grown anything.
Everything I learned was online.

Up until a few weeks ago everything was going great (or so I thought) I live in a motorhome and am growing them under UFO LED tri-band red blue orange lights.
Up until a month ago I was giving them a couple hours in a sunlit window, but now I have 58 (of the 81 planted so far) of them that survived so I stopped all the moving around and just keep them growlight only.

They were all growing a good blue-green and beautiful..the joy of my world...:)

About a month ago I started to notice little gnats flying around and some patches of green moss developing on the surface.

About a week later I noticed some of the lower needles turning yellow on a few of the seedlings all different stages of growth.

I went to my local nursery (100years in business) with some gnats on a piece of tape and my guy ( who I call Yoda) said they were fungus gnats and I was probably watering wrong.

I was just pouring a small amount on top every couple days when it looked dry, and he said I was over-underwatering.

He said, I should water thouroughly once a week and only water when the top was about 3/4 of an inch dry.

He said I could do a Nemotode treatment to kill off the gnats, so I did that about a week and a half ago and am watering the way he instructed.
The gnats have decreased by about 70%.

Over the last week I have about 6 seedling (mostly the oldest ones 6-9 inches, that have totally dried out needles working their way up from the bottom about 1/3 of the way up.

Now a few days ago I start notice more of the seedlings are getting this, some of them only 2 inches tall.

I look at them 10 times a day (they live in the bunk next to mine in the RV.
Everyday new dead needles on more seedlings.

As you can understand I'm in a panic about this.

Is this the fungus gnats eating the roots?

Are the grow lights not enough and they need to
go back to getting a little real sunlight too?

Should I repot them all?
(Yoda said it wasn't needed to plant them in regular dirt from the area Tree original came from because there was lots of other bugs and stuff in the dirt that
make it really hard on fragile seedlings...almost NO seedlings come from the 1000's of pine trees in Los Angeles naturally because of the heat and non-pine conditions...they were all planted by humans.)

The guy at the nursery is amazing and they have hundreds of different plants, veg and trees, all beautiful and healthy, but no pine trees.
Did he give me good advice for pines?

Is there something I can do to stop this from spreading to all the seedlings?

I need a pine expert...these seedlings are abosolutely ALL I have right now and I don't want to fail them...I just can't.

Please help.
Thank you
Count Boogie

Answer
I tend to agree with the nursery--too much water. Also the pot (cup) you have them in are too small and the seedlings need replanting into larger pots with hole in the bottom to allow water to drain. The gnats are not eating the roots but the wet conditions are allow fungi like a damping off fungi to grow in the pot and this can kill the seedlings. I would genitally remove the seedlings and at once plant them in a larger pot with drainage in potting soil that contains a water holding mixture. And do not water unless the top 1 or so of soil is dry. They can do well in the sun but better in a partial shade and watch that they do not dry out. Here is some information on Damping off fungi on container grown pine seedlings. http://www.bugwood.org/container/dampingoff.html