PRESENT SITUATION OF THE CITRUS LEPROSIS IN ARGENTINA

54
XVIII Conference of the IOCV
PRESENT SITUATION OF THE CITRUS LEPROSIS IN ARGENTINA AND PARAGUAY
Sara Cáceres1, Alcides Aguirre1, Norma Costa2, Luis Gonzales Segaña3, Nelson Fariña4,
Juliana Freitas-Astúa5, Gilberto J. Moraes6, Aline D. Tassi 7& Elliot W. Kitajima7
EEA Bella Vista, INTA;
EEA Concórdia, INTA, Argentina;
3
Fac.Agronomia, Univ.Nac. Assunción, San Lorenzo, Paraguay;
4
SENAVE, Assunción, Paraguay;
5
Centro APTA Citros e Embrapa Mandioca e Fruticultura Tropical, 44300-000 Cruz das Almas,
BA, Brazil;
6
Dept. Entomol. & Zool.Agric., 7 Dept. Fitopatol. & Nematol., ESALQ/USP, Piracicaba, SP,
Brazil.
1
2
Citrus leprosis was first reported in South América in Paraguay and Argentina in the 1930’s
and referred to as “lepra explosiva”. Symptom comparison with the “scaly bark” and ”nail head
rust” described in Florida since the beginning of the 20th century led to the conclusion that both
diseases were the same. First evidences of the involvement of the tenuipalpid mite Brevipalpus
obovatus in the transmission of the disease were produced at Bella Vista and Concordia,
Argentina. Further studies confirmed that CL was viral in nature and is caused largely by the
Citrus leprosis virus cytoplasmic type (CiLV-C) and very rarely by the nuclear type (CiLV-N).
Argentina occupies the 5th place in the world in fresh fruit citrus production, with ca. 140,000 Ha
of planted area and an yield of 3 million tons. Most of sweet oranges and mandarins are planted in
the Northern provinces (Misiones, Corrientes and Entre Ríos), usually in small orchards, for table
and industry, totaling ca. 30,000 Ha. Leprosis occurs endemically but erratically in these regions,
mostly in sweet orange. There is no systematic control of the mite vector, but a combination of
pruning and chemical control of the mite has been successful. Analysis made on symptomatic
leaves, collected from sweet orange and mandarins grown at Provinces of Missiones, Corrientes
and Entre Ríos, by transmission electron microscopy (TEM) and RT-PCR confirmed that the
causal agent of leprosis is CiLV-C. Mites collected from sweet orange in B.Vista and Concordia
revealed a mixed infestation by B. phoenicis and B. obovatus, but from a mandarin in Bella Vista,
only B. phoenicis was found. Interestingly, among the mixed infestation in sweet orange in these
two areas, adult females with asymmetric number of solenidion in the tarsus of leg II were found,
whose nature is not yet known. Which among these mites in mixed infection transmit the virus
is still an open question. In Paraguay, sweet oranges are cultivated, usually in small properties,
in the Dept. Itapua, Alto Paraná, Cordillera and Boquerón, totaling ca. 12,000 Ha. Leprosis
was found endemically infecting sweet orange in most of visited orchards, and the causal virus
identified as CiLV-C by TEM and RT-PCR. Mites were collected only in sweet oranges from
Boquerón, and identified as B. phoenicis. In general, in Argentina and Paraguay, leprosis is
not considered as a major disease and there is no special program to control the mite vector.
Genome from isolates of CiLV-C from Argentina and Paraguay were not significantly different
from other isolates, which is coherent to the view that this virus has a small variability.
Financial support from FAPESP, CNPq and INBIO.
Citrus Research & Technology, Cordeirópolis, v.31, Suplemento, p.1-129, 2010