Maybe I shouldn't have done this, but I used thatch from my lawn to mulch my vegetable plants in containers this year. I applied weed & feed to that lawn last year, but thought that a whole season of weathering and growth would have decomposed the chemicals to the point that they were safe. Anyway, shortly after light mulching, my basil plants and all my greens started dying. Remove the thatch mulch ASAP? Probably something else? Thanks!