Hi, I was hoping someone could help me identify the problem with my morning glory vines. The vines are growing and have already produced a large bloom (see pictures), but the leaves have developed a spotty white pattern. It does not look like rust to me (based on internet pictures). I'm thinking it could be a nutrient deficiency, but deficient of what?

Here's more info:

* I am in Austin, TX (Zone 8b)

* I planted them around Feb 14 directly into the ground (clay soil)

* They receive dappled sunlight from 10-1, direct sun from 1-3, and dappled sun from 3-5. I figure that's about 5.5 hours of sunlight

* I feed them about every 2 weeks with a balanced Miracle Gro water soluble fertilizer.

Any help appreciated!

-M (newbie)