Like many (most?) places in the world, tomatoes are everyone's favorite garden plant here. And since the fungus (relative of the infamous Irish potato blight of the 1840s) is so prevalent, we're up on all the tricks.
- Exclusion and hygiene don't help too much as the spores are airborne and can travel very long distances. So if your neighbor has blighted tomato plants, yours are going down soon!
- Resistant varieties, at least the ones we've tried, help a little bit, they may delay the death of your plants by 1-2 weeks, but that's not long enough for most people to switch from a traditional heirloom they love to a totally different variety they may not like much. I've tried 3 resistant varieties so far and have not been impressed with the results yet. Another variety is in this year, we'll see...
nature chooses which ones survive and prosper
...ha, ha... Nature likes to remind us that we're at 43°N and tomatoes are from Mexico, and that we're out of our minds trying to grow them here in the cool and damp this far from the Equator! Nature sentences all our tomatoes to death, it's just us stubborn humans that persist in this madness because we like tomatoes so much. Another problem is that maybe the difference between varieties is how bad the blight gets how fast. By leaving your blighted tomatoes in the ground to see, you're helping broadcast more spores into the atmosphere to ruin everyone else's plants. So...
- Timing: That would be nice, but it's not a luxury we have in our climate except if we use greenhouses. Freezes are possible up until 5 weeks before the summer solstice! If I had a bigger and more isolated garden I would run more trials and plant out at several dates and see how the weather holds up. But since I don't have much space and our season is just long enough to get some good production from late July to maybe mid-October here, it's a bit of a one shot deal.
People who plant some new plants late, say around the summer solstice, say that their plants, being younger, sometimes resist the blight for a week or two more than the older plants do.
Thanks for the input, and still looking for anyone who's used the Korean remedy. I'll probably do the experiment anyway this Fall and hope I'll remember to report back. But a comrade in arms or two would be nice. There is late tomato blight on the East Coast of the US now, so it's not just a European thing anymore.