White hairs (?) at marigold stem base

[Lir]

Beginner gardener here. Can anyone tell me what these white hairs are? (See photos) The plants themselves look fine, for now...
I had another marigold plant that had this and it died.
What should I do to save them from a similar fate?
Help would be much appreciated

 

[Anniekay]

I don't use your system of watering, but I would say that is mildew which could be caused by those watering heads being too close to the stem. The main place plants need water is around and below the leaf canopy, not at the main stalk.

The feeder roots which take up the water are spread out from the stem area and take up water where rainfall would naturally deposit the majority of it which is just outside the edge of the leaf canopy.

 

[nao57]

I have to agree with Annie. You might want to pull the drip watering feeder back away from the plants base just a bit. Enough that it still gets water but that its not being constantly kept wet. What we do out in the southwest is that we also will put down wood bits, wood scrap, chips, or even cardboard around the base of the plants to shield them from the heat. This is because the TOP of the plant LIKES heat. But the stem, base, and roots don't. We have to do that or the low humidity with heat messes our plants up. You could use that. But if you are back east or in a place with lots of water you CAN get too much water, which leads to mold.

You can also put timers on your irrigation system where you have it turn off to let the plants dry out if they get too much. But just make sure it goes back on.

 

[cpp gardener]

It's a fungus feeding on dead plant material. Remove the dead leaves it is feeding on and you remove the problem.

 

[Ladystoic]

In my opinion, both answers are correct. There is an excess of water around the plant and a fungus is growing on the dead leaves due to the damp. If you remove the dead leaves it should go away.