Apple varieties Diel/Lukas
Today, apple varieties are classified according to their ripening time into summer, autumn, and winter apples. Summer apples reach full ripeness on the tree around the end of September. Autumn apples ripen from the beginning of October to mid-November and require some storage. Apples that ripen only after mid-November or later are called winter apples. A further classification is based on their use (cider, dessert, cooking, etc.). August Friedrich Adrian Diel (1756–1839) was a physician and fruit breeder. He is considered the founder of pomology. Diel attempted to classify fruits according to specific characteristics, such as shape, color, and taste, in his own system. Diel is also called the Linnaeus of German pomology. Karl Friedrich Eduard Lucas (1816–1882) is considered one of the most influential pomologists of the 19th century. Among other works, he published a "Complete Handbook of Fruit Cultivation." This was revised in 1981 and published in its 30th edition. He founded his own pomological institute in Reutlingen, Germany, in 1860. He also founded the first German Pomological Society in 1860. His system for classifying pears and apples into 15 classes remained in use well into the 20th century. However, all classifications suffer from the problem of clear differentiation and consistency. A logical and consistently comprehensible categorization of the many different nuances in fruit varieties remains difficult to this day. Since the Diel/Lucas system can still be found in pomological literature, it will be explained below.