growth rate on CE and PE at 1.0 g L−1 was 4.1 and 6.9 mm/day,
while on GE it was similar to the control (16.3 mm). The mycelial
growth of L. theobromae was completely inhibited by CE and PE
at 5.0 and 10.0 g L−1, in contrast to a growth rate of 28.3 mm/day
for the control treatment (Fig. 2c). PE was more effective in
reducing mycelial growth than CE at all concentrations. Growth
rates were not affected significantly by GE.
3.3. Effective dose (ED50 value) of plant extracts
The ED50 value of plant extracts varied depending on the tolerance
of pathogens and their structure (conidia and mycelium).
It was observed that the ED50 values of plant extracts for
conidial germination of these pathogens were less than that
of mycelial growth, except in Fusarium spp. (Table 1). The
ED50 value of CE for 50% inhibition of conidial germination
was 0.091, 0.758 and 0.050 g L−1 of culture media for
C musae, Fusarium spp., and L. theobromae, respectively. GE
was less effective than CE and PE in inhibiting conidial germination.
The ED50 of CE, PE and GE for mycelial growth for all three
pathogens was not consistent. The ED50 value of PE was less
than CE for mycelial growth ofFusariumspp. and L. theobromae
but the ED50 value of CE was less than PE for C. musae. GE
had no effect on mycelial growth of all pathogens.
3.4. Efficacy of integrated methods on crown rot
development
The effects of the integrated treatments on crown rot disease
of bananas during storage for 7 weeks at 13 ◦C are shown
in Fig. 3. CE significantly reduced severity of crown rot when
the treatments were applied after conidial inoculation (Fig. 3a).
Disease severity was least in bananas treated with CE, followed
by a combination of CE and HWT, HWT, and combinations of
CE and chitosan, and CBZ and chitosan. CE gave more than
25% inhibition of the disease over a storage period of 7 weeks
at 13 ◦C. At week 5, disease severity was 100% in untreated
bananas with a score of 5.5 while all treated bananas had 25–50%
disease severity with scores of 2–3.
CE suppressed disease (score 3.6) significantly better than
CBZ (score 4.6). Treatments such as chitosan, HWT and the