Ask-a-Dave's-Gardener: Milkweed Leaf Issues, 2 by Chenoa0125

Chenoa0125 wrote:
I really need some advice on an issue I am having with my milkweed. My tropical and swamp milkweeds have come up from cuttings I took last year and some I have grown from seed. Everything has been going great they are about to knees length, bushy healthy looking, and then all of a sudden the leaves are turning yellow with some dark spots on them and falling at the very lightest touch. When I go to trying to research this, I have read about the leaf spot bacteria, soil PH too high, chlorosis, not enough nutrients, too much water, and not enough water. I am at a loss for words on this because I have 3 cat\'s already and cannot risk having all my milkweed going bad.
I am going to check the ph when I get home tonight but wanted to see if anyone had any ideas on what I should be checking or if I should just check everything.
They are growing in pretty much sandy soil, zone 8b. Not too terribly much sun but also not in a lot of shade. I am finding that it seems to be the tropical milkweed mostly affected. Although my other ones have the same ordeal just not on every plant.
If anyone has any advice please let me know. I have attached some pictures from online that are almost identical to what mine look like. I will take my own photos tonight when I get home.
Thanks in advance for any help on this.