Why Is My Yellow Summer Squash Leaves Turning White/yellow?

Question

Not powdery mildew. The leaf itself is actually pale yellow/white. Grown in pot in mixture of compost/peat moss/vermiculite. Have used this mix before growing squash with much success. Plant covered with garden fabric at night to deter pickle worm. Plant in sun approximately 6 hours a day. Plant size about 3 inches tall. Plant age about 30 days. Day temp around 75/80 degrees. Night temp around 55 degrees. No fertilizer or pesticides have been used at this time. 2 other plants in same growing conditions are a little on the pale side, but otherwise normal.

Answer 1

It certainly sounds like you have ideal conditions, but perhaps the young plant is getting too much heat from the sun. https://www.gardeningknowhow.com/plant-problems/environmental/leaf-scald-in-plants.htm
The other likely possibility is that this is a strain that produces white or silvery leaves. If you're sure there's no powdery mildew, I would assume it's just the nature of the type of plant you've chosen.