I have planted some better boy tomatoes purchased from a local suppler. The plants are young and appeared heathly a week ago. Now the upper leasves are getting brown spots on them that is progressing into larger spots mixed with yellow and then the leaf stem is turning brown. Can anyone identify this problem and advise me if it can be cured. I have not had anything planted in these raised beds for two years and have not had this problem before in years past.