Phyllocnistis citrella and its relationship with the citrus canker bacterium Xanthomonas axonopodis pv. citri in Brazil Myrian Rybak Department of Plant Pathology, University of Florida

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Phyllocnistis citrella and its relationship with
the citrus canker bacterium Xanthomonas
axonopodis pv. citri in Brazil Myrian Rybak
Department of Plant Pathology, University of
Florida
Objective of the study

The present study was conducted to determine the
relationships between different levels of the
lesions caused by the CLM and the degree of
infections by Xanthomonas axonopodis pv citri in
citrus.
Treatments
1 Leaves without miner sprayed with distilled
water. 2 Leaves without miner inoculate with
bacteria. 3 Leaves infected with 2nd instar
larvae and inoculated with bacteria. 4 Leaves
infected with 3rd instar larvae and inoculated
with bacteria 5 Leaves infected with miner
pupae and inoculated with bacteria. 6 Fully
expanded leaves injured with carborundum and
inoculated with bacteria.
Canker infected fruit, foliage, and
stems. (Courtesy T.R. Gottwald)
Table 1. Effect of injuries caused by different
instars of P. citrella
R E S U L T S and D I S C U S S
I O N
Treatments 7 days 8 days
1 0 0
2 11 41
3 87 94.3
4 87 98.3
5 89 100
6 94.1 97
7 days
7 days
7 days
14 days

• Plant inoculated with 2nd and 3rd instar larvae
  or pupae showed high percentages (94.3, 98.3 and
  100 respectively) of bacterium-infected leaves.
• The damage caused by this insect was responsible
  for the increase in citrus canker infection.
• The leaf infection rate by Xac on pre-injured
  leaves was similar to that observed on
  mechanically damaged leaves inoculated with the
  bacteria with 94.1 to 97.0 of the leaf
  presented pustules.

Figure 1 Effect of injuries caused by different
instars of P. citrella on the infection with the
citrus canker bacterium Xac in C. sinensis



Conclusion
The significance of the damages caused by CLM in
terms of the increase of citrus canker is noted
since the favorable microclimatic conditions of
temperature and relative humidity inside the
mines account for an improved development of the
bacterium

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