What’s wrong with my plant

[Sohigh93]

Can someone help me determine what this is on my plant it’s my first grow. And it’s only in this one plant

 

[Dr.B]

Please post the details.

Growing media?
Pot size?
Previous insect or fungus issues?
Nutrients being used?
Watering schedule?
Ec/ppm?
pH? (Growing media and water in/out)
Lighting?
Air turnover/movement?
Day/night temperature and the overall range?
Relative humidity and the overall range?

Thanx