Ornamental Plant Breeding

Rhododendrons a popular horticulture species because they are so beautiful.

But they are prone to failure in the garden.

In the garden, root rot disease, caused by the invasive fungus-like soil pathogen Phytophthora cinnamomi, is a significant problem and associated with plant mortality. The photo on the left shows a Rhododendron with root rot disease caused by the invasive soil pathogen Phytophthora cinnamomi.


Using traditional plant breeding methods, researchers at Holden are transferring disease resistance from wild rhododendron species to hybrid varieties that are grown as ornamental plants in gardens. The increased root rot resistance has also enabled these plants to be grown in much warmer climates (e.g. the Gulf South) where the root disease pressure is greater.


Holden has a long tradition of woody plant breeding for the home landscape with much of the research on rhododendron conducted at the David G. Leach Research Station. For more information about this tradition of plant breeding, please visit the Leach Research Station web page.