My early plantings of basil were taken down by downy mildew. Every single one of them even though I scattered them around the yard. I'm a bit worried that the seed might be contaminated. But how would I know?
The University of Florida Institute of Food and Agricultural Sciences is trying to find ways to prevent it from spreading without the use of chemicals. Red light seems to help. Now they used actual red light which wouldn't work in the garden at all. But people use red mulch in tomatoes to increase the number of fruit on the plants. I wonder if a red mulch under basil would help. I really do hate plastic mulches, but if it meant that I got basil every year, I'd do it. I hate row covers, yet I use them on so many things. Though I suppose the first line of defense might be to find another seed source. I don't know if mine is contaminated, but two years in a row I've gotten the disease and the extension service said that basil downy mildew had no reported cases in Massachusetts at the time. So it seems likely.