Do we know if we have late blight in south-western BC, or Vancouver Island? I'm going to copper spray my tomatoes today, but looking at the weather forecast -- cool and wet for the next week at least -- I'm considering covering all 30 or so plants. Thoughts?
I use copper spray on my tomatoes every year when rain arrives in late summer or fall. I've already applied it twice when rain was in the forecast, but the rain didn't arrive or it barely showered. So, I'm not sure if the spray made any difference. Now, I'm going to wait until the forecast rain ends (if it arrives at all) before spraying again. The copper spray has worked quite well in previous years.
I get blight some wet years and just give up. It devastates cucumbers, some melons, potatoes and tomatoes. I found nothing works.
Late blight, Phytophthera infestans, unfortunately is a very real problem in BC especially since the 1990s when changes took place in its mating types that made it a much more serious disease of tomatoes and potatoes than previously. In my experience, the strategy most often recommended to control the blight on tomatoes is to cover the plants with a clear roof-type structure that prevents rain from depositing spores on the leaves. Also, drip irrigation rather than overhead sprinkling helps greatly in preventing spores in the soil from splashing up into the plants. There are lots of good suggestions in this article about how home gardeners can prevent late blight from becoming a problem in the first place: https://www2.gov.bc.ca/assets/gov/f...lightdisease-homegardenpotatoestomatoesss.pdf
