Colletotrichum gloeosporioides, a new causal agent of citrus post-bloom fruit drop

Author(s)

Lima, Waleria Guerreiro ^[1] ; Sposito, Marcel Bellato ^[2] ; Amorim, Lilian ^[3] ; Goncalves, Fabricio Packer ^[3] ; Melo de Filho, Pericles Albuquerque ^[1]

Affiliation

^[1] Univ Fed Rural Pernambuco, Dept Fitossanidade, BR-50460230 Recife, PE - Brazil

^[2] Fundecitrus, Dept Cient, BR-14801970 Sao Paulo - Brazil

^[3] Univ Sao Paulo, Escola Super Ag Luiz Queiroz, Dept Fitopatol & Nematol, BR-13418900 Sao Paulo - Brazil

• Document type: Journal article
• Source: European Journal of Plant Pathology; v. 131, n. 1, p. 157-165, Sept. 2011.
• Web of Science Citations: 34

Abstract

Citrus post-bloom fruit drop (caused by Colletotrichum acutatum) frequently occurs in the southwestern region of São Paulo State, Brazil. A survey of Colletotrichum isolates associated with symptoms of post-bloom fruit drop in São Paulo State showed C. gloeosporioides in addition to C. acutatum. The objectives of this study were to confirm the identification of C. gloeosporioides isolated from symptomatic citrus flowers, to test the pathogenicity of C. gloeosporioides isolates, to compare the development of disease caused by C. gloeosporioides and C. acutatum, and to determine the frequency of C. gloeosporioides in a sample of isolates obtained from symptomatic flowers in different regions of São Paulo State. Through the use of species-specific primers by PCR, 17.3% of 139 isolates were C. gloeosporioides, and the remaining 82.7% were C. acutatum. The pathogenicity tests, carried out in 3-year old potted plants of sweet oranges indicated that both species caused typical symptoms of the disease including blossom blight and persistent calyces. Incubation periods (3.5 and 3.9 days, respectively, for C. acutatum and C. gloeosporioides) and fruit sets (6.7 and 8.5%, respectively for C. acutatum and C. gloeosporioides) were similar for both species. The incidences of blossom blight and persistent calyces were higher on plants inoculated with C. acutatum than in those inoculated with C. gloeosporioides. Conidial germination was similar for both species under different temperatures and wetness periods. Under optimal conditions, appressorium formation and melanisation were higher for C. gloeosporioides than for C. acutatum. These results indicated that Colletotrichum gloeosporioides is a new causal agent of post-bloom fruit drop. (AU)

• FAPESP's process: 08/54176-4 - Molecular epidemiology and management of postbloom fruit drop of citrus in new planting areas in São Paulo State
• Grantee: Lilian Amorim
• Support Opportunities: Research Projects - Thematic Grants