Good Morning Laura, 

Thank you for contacting the U of M Extension Service. 

From viewing your photos, it does appear to be aster yellows: https://extension.umn.edu/plant-diseases/aster-yellows

Above is a link about aster yellows. 

Here is another link about spider mites: https://extension.umn.edu/yard-and-garden-insects/spider-mites

Good Luck!

Laura, 

If you read through the information on the weblink it states: 

Cultural controls

• Completely remove infected plants from the garden. Once a plant is infected with aster yellows, there is no way to cure it. This can be difficult but is a necessary step to saving other susceptible plants from becoming infected.
• Because aster yellows does not survive in dead plant tissue, there are a couple of disposal options for infected plants.
  

You should remove the plant and the roots. Read the cultural controls section. You should be able to plant another plant in the same area. 

Good Luck!

You are welcome!