１．建立留种田 选择无病、根茎短、生长集中、高产的植株，单独进行繁殖，选择优良品种留种是防止地黄退化的关键措施。 ２．防止混杂 在春天和秋天栽的留种田中，根据幼苗形态逐株进行检查，发现劣株主即刨出，这就是去杂。去杂应尽早进行，如果根茎已经膨大，就不容易将杂种 1. The establishment of stay farming to choose disease-free, short rhizomes, concentrated growth, high-yielding plants, separate breeding, selection of fine varieties to stay seed is to prevent the degradation of Rehmannia key measures. 2. Prevent hybrid planted in the spring and autumn to stay in the field, according to seedling morphology by strain inspection, found that bad stalks that are digging out, this is going to miscellaneous. Go to the hybrid as soon as possible, if the rhizome has swollen, it is not easy to hybrid