Question
Could you tell me why the bottom leaves on my tall phlox (David,Laura,and Nikki) are turning yellow and dying? The plants came up thick and healthy looking. The leaves next to the ground at the bottom of the plant are yellow and is moving on up the plant. Thank you for any help.

Answer
Kitty:
If the whole leaves are turning pale green then yellow with no spots or lesions, I doubt if it is a bona fide infectious type of disease- it merely may be a nutritional or water imbalance in the roots.  Be sure the soil isn't drying out and consider having a soil test done to determine if there are any nutients deficient. Talk to your local garden center about having this done.

Enjoy,
Steve