The 19th Wine Industry Financial Symposium on Monday comes at one of the most challenging times for the Napa Valley wine business in decades. The economy has dealt a heavy blow to the valley’s mostly high-end wines, and Mother Nature has added her share of problems as well. This cool year is returning low yields on the grapes that have been harvested, with prime cabernet and chardonnay crops running two to three weeks late. Harvest seems likely to extend into the rainy season with the worry about rot, split grapes and reduced concentration of flavors. In this environment, David Freed, founder of the symposium and chairman of huge grapegrowing company, the Silverado Group, will announce the results of his annual poll of vintners and growers to attendees.