Richard T. Olsen and Thomas G. Ranney
NC State University, Dept. of Horticultural Science, Fletcher, NC
The bi-generic hybrid ◊Chitalpa taskentensis (Catalpa bignonioides Walt. ◊ Chilopsis linearis (Cav.) Sweet) was first bred in Uzbekistan in the 1960ís and introduced to the United States in 1977. ◊Chitalpa has performed well in the arid southwestern U.S., but is susceptible to powdery mildew in more humid regions and is also a host to Catalpa sphinx moth larvae. No further work has been done to improve ◊Chitalpa, due principally to the sterility of the original hybrids. In order to initiate a breeding program for ◊Chitalpa, we successfully developed allotetraploids to restore fertility. Screening studies for both powdery mildew susceptibility and Catalpa sphinx moth resistance have been initiated and involve species and taxa from sections Catalpa (temperate deciduous species) and Macrocatalpa (evergreen species native to the Caribbean) of the genus Catalpa and new cultivars of the monotypic Chilopsis linearis. Additional studies have begun to investigate sexual compatibility across ploidy levels, embryo rescue to overcome triploid blocks, tetraploid mentor pollen for overcoming low diploid pollen viability, and the breakdown of self-incompatibility in induced polyploid ◊Chitalpa.