2017 ASHS Annual Conference

Pitahaya (Dragon fruit, Hylocereus spp.) are vining and climbing cacti native to tropical America, from Mexico to Northern South America. These species, grown for their edible fruit, adapt well to Southern California where they are being evaluated and promoted as a new, viable crop alternative because of their drought tolerance and their potential to produce high marketable yields of excellent quality fruit sold for fresh consumption. Contrary to their native tropical habitat where many foliar diseases are primary problems, in our arid climate soilborne pathogens may pose the greater challenge as they have been suspected to cause unexplained plant decline or even plant death. The objective of this project was to evaluate cultivars from 5 different species (H. polyrhizus, H. ocamponis, H. guatemalensis, H. undatus, H. megalanthus) for their susceptibility to the Southern root-knot nematode (Meloidogyne incognita). Cuttings were established and raised in pasteurized sand. For each Pitahaya species 5 plants were transplanted into pots with 1500 cm³ pasteurized sandy soil infested with 200 M. incognita eggs/100 cm³ or into non-infested soil. The trial was incubated for 8 weeks at 25±3˚C in a greenhouse with ambient light. At trial termination, root galling (scale 0-10, 0 = no galls) ranged from 2.0 to 3.8 and the reproduction factor (R=Pf/Pi) from 2.4 to 26.7. All Hylocereus spp. were susceptible to M. incognita while H. ocamponis cv. Vadivia Roja had the highest gall rating and largest number of eggs per root system. This might support growers’ observations of cv. Valdivia Roja’s particular susceptibility to deterioration of its root system. In general, the Southern root-knot nematode has the potential to become a major threat to the growth of California’s Pitahaya production industry.