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Phyllocnistis citrella and its relationship with the citrus canker bacterium Phyllocnistis citrella and its relationship with the citrus canker bacterium Xanthomonas axonopodisXanthomonas axonopodis pv. pv. citricitri in Brazil in Brazil Myrian Rybak

Department of Plant Pathology, University of Florida

R E S U L T S and D I S C U S S I O N R E S U L T S and D I S C U S S I O N

The The presentpresent study was conducted to determine the relationships between different levels of the lesions study was conducted to determine the relationships between different levels of the lesions caused by the CLM and the degree of infections by caused by the CLM and the degree of infections by Xanthomonas axonopodis pv citri in Xanthomonas axonopodis pv citri in citrus. citrus.

1 Leaves without miner sprayed with distilled water.1 Leaves without miner sprayed with distilled water.

2 Leaves without miner inoculate with bacteria. 2 Leaves without miner inoculate with bacteria.

3 Leaves infected with 23 Leaves infected with 2ndnd instar larvae and inoculated with bacteria. instar larvae and inoculated with bacteria.

4 Leaves infected with 34 Leaves infected with 3rdrd instar larvae and inoculated with bacteria instar larvae and inoculated with bacteria

5 Leaves infected with miner pupae and inoculated with bacteria.5 Leaves infected with miner pupae and inoculated with bacteria.

6 Fully expanded leaves injured with carborundum and inoculated 6 Fully expanded leaves injured with carborundum and inoculated with bacteria. with bacteria.

TreatmentsTreatments

PlantPlant inoculated with 2nd and 3rd instar larvae or pupae showed high percentages inoculated with 2nd and 3rd instar larvae or pupae showed high percentages (94.3, 98.3 and 100 % respectively) of bacterium-infected leaves.(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 The damage caused by this insect was responsible for the increase in citrus canker infection.infection.

The leaf infection rate by Xac on pre-injured leaves was similar to that observed on 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 mechanically damaged leaves inoculated with the bacteria with 94.1 to 97.0 % of the % of the leaf presented pustules.leaf presented pustules.

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

Canker infected fruit, foliage, and stems. (Courtesy T.R. GottwaldCanker infected fruit, foliage, and stems. (Courtesy T.R. Gottwald))

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

0

20

40

60

80

100

120

1 2 3 4 5 6

Treatment

% o

f le

av

es

wit

h c

an

ke

r

7 days7 days7 days7 days7 days

14 days

Table 1. Effect of injuries caused by Table 1. Effect of injuries caused by different instars of P. citrelladifferent instars of P. citrella

TreatmentsTreatments 7 days7 days 8 days 8 days

11 00 00

22 1111 4141

33 8787 94.394.3

44 8787 98.398.3

55 8989 100100

66 94.194.1 9797

Objective of the studyObjective of the study

ConclusionConclusion