2014 ASHS Annual Conference

Pitahaya or dragon fruit (Hylocereus spp. and Selenicereus megalanthus), is the name of a vining cactus and the fruit it produces. Pitahaya adapts well to various climates and can be a profitable alternative for growers in Southern Coastal California Counties, where a growing interest, particularly among small-scale producers looking for profitable alternatives, has increased and so has the acreage planted to this crop.

Field plots were established in three different California locations to address research issues identified as critical for commercial production. However, as the number of commercial growers, the number of acres and the geographic dispersion of the crop increases, so do the challenges for commercial production. Cactus Virus X (CVX), whose presence on pitahaya was first reported in Taiwan in 2003 (M.R. Liou et al.) is an example of these new challenges. CVX is found worldwide and it infects many species in the Cactaceae family (Cereus, Saguaro, Opuntia, Zygocactus and Hylocereus). Infected plants can be asymptomatic or show symptoms like distorted aureoles, deformed spines, necrosis, mottling, and reddening of the stems.

Virus-like symptoms were first observed/documented at the UC South Coast REC in early 2011 and the presence of CVX in Pitahaya was first reported in California later that year. A set of 54 samples was analyzed/screened by a private laboratory using a Polymerase Chain Reaction (PCR) test and the virus was present in an estimated 90% of the samples analyzed. The availability of an ELISA test to screen for CVX allowed the analysis of an additional 200 samples in a more rapid and cost effective way with the majority of them being positive for the virus. Although the effect/impact of the virus for commercial production is still not clear, it represents a significant threat to the growth of this crop.

Three main strains of CVX have been identified to date. There are no known vectors for the virus and its transmission occurs primarily by mechanical means, including but not limited to cultural practices like pruning, harvesting and propagation. Additionally, the virus can be transmitted naturally through plant contact and root grafting beneath the soil. We will discuss/present guidelines for field identification and best management practices commercial pitahaya growers can use to manage CVX and prevent further contamination once present in their production fields.