I've used solarization to eliminate many soil-born diseases, especially
early blight. Solarized soil produces crops that have few problems.
Supposedly, the USDA has pushed solarization as a replacement for soil
fumigants that are being outlawed for strawberry producers. I produce
gorgeous disease-free berries on solarized ground. Never have a problem or
apply anything.
A couple of things from experience about solarizing ground. First, make
sure the soil in the top six inches is really moist. Second, use timbers,
weights or anything heavy to seal the plastic. The more airtight you make
it, the faster the soil steams. Third, get a soil thermometer; don't try to
guess at temperatures.
Solarization cleaned up problem ground for me so that I could plant peach
trees in a hot climate where blights and other fungal diseases are huge
problems with peaches. My trees and fruit were disease-free with only a
late winter dormant oil spray and three applications of neem seed oil spray
at bud break, blossom fall and three weeks later.
Doreen Howard