A rootstock is the part of the plant that produces the root system. For many fruit trees it is often genetically different than the scion the top portion of the plant that is grafted to the rootstock. The scion gives rise to leaves, stems, flowers, and fruit.
Commercial avocado trees are propagated by grafting scions of desirable cultivars onto various rootstocks with the most popular avocado cultivar being the Hass avocado. While avocados can be grown from seeds, their fruit quality and yield potential can vary dramatically. Therefore, it is more advantageous for avocado growers to have both a scion and rootstock that has the most desirable characteristics, enabling the best "plants" to be grown for profitability and consumption.
Prior to the development of specific avocado rootstocks, nurseries produced avocado trees, such as the Hass cultivar, on arbitrary avocado rootstocks, knowing almost nothing about the rootstocks' genetics. Because different rootstocks were used, it led often to orchards producing avocados of varying quality.
The three new rootstocks were initially selected for PRR-tolerance based on approximately two years of screening under greenhouse conditions at UCR. Eventually, the three varieties were tested throughout several locations in California over many years to determine their viability for public release.
The UCR Office of Technology Commercialization is pursuing licensees for all three new avocado rootstocks for their successful commercialization, and will give preference to California avocado nurseries and growers.
The PRR-causing pathogen (Phytophthora cinnamomi) was first identified as causing PRR in avocado in Puerto Rico in 1928. It was eventually determined in 1942 to be responsible
|Contact: Iqbal Pittalwala|
University of California - Riverside