Rapidly expanding leaves and continuously growing fruit tissues
are most vulnerable to infection, and field resistance of trees to Xcc
is directly related to tissue juvenility (Graham et al., 1992). Citrus
cultivars and species with greater frequency, size, and duration of
leaf flushes and duration of fruit growth are more field-susceptible
to Xcc than less vigorous cultivars or those whose foliage matures
more rapidly (Favaro et al., 2014; Gottwald et al., 1993).