What caused this?

[hoodat]

Growers fumigate the soil but that is impractical and dangerous in the home garden. About all you can do is plant mosaic resistant tomatoes and potatoes but none that I know of are completely immune.

 

[seedcorn]

Tomatoes, peppers, eggplants will be susceptible. For next year, I'd compost as much as I could or move the garden.