Bump I've had this problem in the past; don't know what caused it. Maybe try posting over at the HOT PEPPERS forum and see what you get. Cheers!

Update: as of today, there are now spots on a Brandywine & a Roma plant. I guess I jinxed them. :(

I also use rainwater and posted this before... Here is a link (2005) to how I water my garden ... Deep watering for heavy feeders growing on upright trellises I should add the nowadays I also use those rather large plastic pots you get when you buy large plants - fill about half-way with leaves and compost (just enuff so the water just ooozes out the pot holes) then dump in rain water from a 5 gal bucket. So the nutrients leak out of the pot with the water. This keeps the plant leaves from getting wet when sprayed from above and allows the water to soak deeply in one area and not be wicked away by the hot summer air. At times I will add coffee grounds to these pots too. Also anything so the water leaks out slowly and soaks in deeply close to the bucket/pot. Keep in mind the plants feed from the root tips and the root tips may be a long way from where the plant stem enters the soil. That is where I place the pots/buckets. Check your root depth/length here...ROOT DEVELOPMENT OF VEGETABLE CROPS

cut & paste from another thread this morning: "Quinclorac kill crabgrass. It's the active ingredient in Drive XLR8, you can use any brand and it will work. Some people (reeljake) uses Sulfosulfuron (Sedge Ender) and it works fine as well. People have have pretty good results keep most weeds out of their bermuda with Celsius and Sulfosulfuron. Plus there is no issues related to applying in hotter temps. Reeljake also uses Dimension with active ingredient dithiopyr as his pre-emergent, I use Prodiamine. With either you want year round coverage to keep ALL WEEDS from germinating. You will need to start your PreM asap to keep winter weeds at bay, then again in Spring for Spring/Summer weeds. PreM: Prodiamine or Dimension Crabgrass: Quinclorac or Sulfosulfuron General weeds (post-emergent): Celsius - 2,4-D will work also but turns grass yellow If you get the correct products, it won't matter what the weed is, it either will never germinate in your yard, thanks to the PreM, or will die when sprayed with the post-emergent."