susceptible cultivars are growing in areas with favorable conditions
for bacterial multiplication. Copper reduces bacterial populations
on leaf surface, but multiple applications are needed to protect fruit
of susceptible citrus varieties. Disadvantages of long-term use of
copper bactericides include induced copper resistance in xanthomonad
populations (Behlau et al., 2012) and accumulation in soils
with potential phytotoxic and adverse environmental effects. The
protective activity of copper is diminished by wind-blown rain that
introduces bacteria directly into stomata (Behlau et al., 2008;
Serizawa and Inoue, 1974). However, other bactericides such as
antibiotic-based products are not as effective as copper because
they lack sufficient residual activity to protect leaf and fruit surfaces