One potential disadvantage. In theory, asexual reproduction should limit genetic variation in a population, and hence, would not be a disadvantage in the long-term evolutionary sense. Taking advantage of asexual reproduction. Gardeners have long taken advantage of the asexual reproduction process in plants. If you've ever taken a cutting from a plant or grafted a plant, you have, too.
Tissue culture is a high-tech version of the same process.
Individuals cells of a plant can be grown aseptically in culture medium. Initially the cells form an undifferentiated cluster of cells, called a callus. These clumps can be divided up transferring them to other cultures producing literally thousands of genetically identical cell masses from an original cell. DNA carrying genes of interest can be inserted into the plant cells and new plants grown. Plants have sex, too.