Development and Evaluation of Rootstocks for Avocado (Persea americana Mill.) Production

The search for alternate/superior avocado (Persea americana Mill.) rootstocks in the United States was initiated in the 1940’s as avocado root rot caused by Phytophthora cinnamomi was devastating the industry.   It was not until 1970, however, that a suitable technique for clonally propagating rootstock material was developed by T. Frolich and R. Platt and another 5 years before this technique was commercialized by H. Brokaw.  The first released clonal rootstock, Duke 7, has been widely planted worldwide and has moderate resistance to the disease.  Since 1975 several additional rootstocks have been released that have improved resistance to avocado root rot as compared to Duke 7 from both the University of California (UC) program as well as that of Westfalia Fruit Estates in South Africa.  While the search for avocado root rot tolerant rootstocks has been the focus of the UC and South Africa programs, salinity tolerant rootstocks has been the focus of the selection program in Israel.  Several seedling lines of the West Indian race have been identified that show high tolerance to saline conditions.  These programs will be discussed in greater detail as well as the cloning process used to propagate the rootstocks.