New findings on the effects of different factors involved in fig limb dieback caused by Neoscytalidium dimidiatum in California

Abstract

The San Joaquin Valley (California, USA) represents an important fig (Ficus carica) production area in the United States. Fig limb dieback represents a serious and emerging disease of fig caused by Neoscytalidium dimidiatum. In the present study we evaluated the effect of tissue age on canker development, the recovery of the fungus from fruit mummies collected in the field, the ability of N. dimidiatum to colonize, under laboratory condition, fig fruits, and the in vitro effects of different water potentials (Ψs) on mycelial growth rate.Results of our study showed that the older branches (> 3-year-old) resulted in longer canker compared to the younger ages. N. dimidiatum was not recovered from the mummies, instead they were colonized by many other fungal saprophytes. Laboratory experiments showed the ability of this species to colonize dried fig fruits from 20 °C to 35 °C. In vitro water potentials experiment showed that the mycelial growth was reduced with the decrease of water potential (from 1–3 -MPa), depending on salt type.