What soil amendments will help alleviate blight on tomatoes, potatoes, carrots etc? Thank you.
Clinton County Michigan
Blight is basically a fungal disease that is going to be specific to certain single crop. It might be two crops in the same family, There is an early blight that is only on tomatoes. There is late blight that is specific to tomatoes and potatoes. If there is anything for carrots, it is obscure. Blight is a catch-all term for any problem but it does not give any information as to what is really going on.
But... here's the big but... you give no symptoms so I can't guess that what you are describing. Tomatoes can get several diseases and a bunch of physiological disorders, Those happen because of something not alive like a fungus or bacteria. All are weather connected... almost always humid or damp air.
Fungal and bacterial diseases can be airborne and not remain or originate in the soil. Some could. Since there is no definition of what the problems were, nothing concrete in the way of information can be offered.
If it was in the soil, moving those particular vegetables to another location in the garden could help. Tomatoes and potatoes belong to the same family of vegetables and could share diseases. But there are no amendments to add to the garden that will make a fungus go away.
Remove diseased plants completely from the garden and burn or bury them where they will not be disturbed.
A better course would be to identify what diseases were active and approach this as preventing problems. This could involve using a preventative fungicide. Fungal problems can be prevented but not cured.