Verticillium wilt?

Young green peppers in small polytunnel showing leaves shrivelled up, brown and dying. No sign of green or blackfly. I pulled them up and destroyed them. Looks like it might be Verticillium wilt from a quick web search. Tomatoes and Cucumbers do not seem to be infected. I understand the virus will be in the soil, but don't know what to do apart from looking for a resistant crop - can anyone help? Thanks!