Potato Dextrose Agar (PDA) contains dextrose as a carbohydrate source which serves as a growth stimulant, and potato infusion that provides a nutrient base for luxuriant growth of most fungi. Agar is added as the solidifying agent. A specified amount of sterile tartaric acid (10%) may be incorporated to lower the pH of the medium to 3.5, so that bacterial growth is inhibited.