Preface: I am a raised bed gardener. Last year, I was a tad late in getting my tomatoes in the ground, then lost everything late summer when a late blight (yellow leaves) caught me and wiped me out. My plants were store bought (Bonnie’s @ Lowe’s); prior year I gre from seed and was overwhelmed with tomatoes. I have had clear plastic over the affected bed aince last summer. What can I do to avoid a return of the blight?