Production costs for this area's botrytized wines are comparatively high. The evaporation and fungus produce low yields, five to six times less than in other Bordeaux regions. The grapes are normally harvested individually from the bunch with pickers going through the vineyards several times between September and November to ensure that the grapes are picked at their optimal points. The wine is then fermented in small oak barrels, further adding to the cost. Even with half bottles of the First Growths priced at several hundred dollars, these wines still have difficulties turning a profit and in the mid 20th century a string of bad vintages drove many growers in the region out of business.