Answer: This is a soil borne problem and can be spread on tools, brought in with transplants, and so on, including I would fear, the sides to the raised bed. I would worry that the problem could be accidently transferred into the new soil, and after all that work, it would be so disappointing!
Resistant varieties are not immune, but when well cared for and grown in otherwise healthy soil may be able to produce well. In some instances, using copious amounts of compost and organic matter in preparing the soil also seems to help resistant plants outgrow the problem. (Be sure you are not adding diseased plants to your compost pile, however.)
Unfortunately, Burpee Big Boy does NOT have the disease resistance of some of the other varieties that are available, so I would strongly suggest you try one that is resistant to verticillium as well as other problems. You might try one of these instead: the new Bush Big Boy(VFNT), Big Beef (VFNTAS), Big Girl (VF), SuperTasty (VFNTAS), Better Boy (VFN)and see if you have better results.
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