Q.What are white splotches on Morning Glory and Moon Flowers
As soon as the seeds germinated, they had white splotches on them, and that progressed quickly into the green being eaten away. Is this white rust, or something else. Is there anything I can do about it other than rip them up. the plants are in a south window indoors, and in previous years, Mornibg Glories have grown there successfully. Even under 20x magnification, I don’t see any spores on the underside. I did see some tiny dark insects, long, possibly with wings, under magnification, but I have got rid of those.
It appears you may have a few issues; both pest damage and perhaps some fungus issues.
Growing the same plant in the same soil for multiple years can lead to fungus diseases.
You can try treating with Neem Oil.
You may want to replace the soil for planting with new soil and even do crop rotation.
Remove any leaves that have fallen and discard; do not compost.
Avoid overhead watering and increase air circulation in the area if possible.
https://www.gardeningknowhow.com/ornamental/vines/morning-glory/morning-glory-diseases.htm