Mildew is a parasitic fungus. It grows in moist, hot air and is found on cloth, fibre, leather goods, strawberry, etc. For example, if strawberry is left in a warm and moist place for many hours, it gets covered with a net of cobweb like threads and blackish powder-like substance. This is mildew. Mildew can be divided into two groups: powdery and downy. Powdery mildew grows on leaves, twigs, flowers, fruits of plants and trees. Downy mildew grows in the inside of plants and is hard to destroy.