The causal agent of citrus postbloom fruit drop, Colletotrichum acutatum, can survive on weeds

Postbloom fruit drop is an important citrus disease caused by Colletotrichum acutatum. Severe outbreaks can develop when rainy periods occur during citrus bloom. Under these conditions, explosive epidemics are observed despite relatively short inoculum dispersal distances typical of this pathogen. C. acutatum can survive on citrus leaf surfaces after formation of appressoria, but survival on weeds has not been characterized. The survival of C. acutatum on seven species of weeds was evaluated under greenhouse conditions by artificial inoculation and subsequent recovery of the pathogen in-vitro. Conidial germination and appressorial development of C. acutatum were observed on the surface of all inoculated leaves. The pathogen was recovered from weed leaves at 30, 60 and 90 days after inoculation. Statistically, there was no difference in survival of C. acutatum among sample times post-inoculation. Although survival varied on different weed species, no symptoms were observed on inoculated leaves. All citrus flowers inoculated with isolates recovered from inoculated weeds showed typical symptoms of postbloom fruit drop. We conclude that the weed species tested may serve as potential alternative hosts for C. acutatum.

[1]  R. Brlansky,et al.  Infection of flower and vegetative tissues of citrus by Colletotrichum acutatum and C. gloeosporioides , 1996 .

[2]  S. Pennypacker,et al.  Weeds as hosts for Colletotrichum coccodes. , 1987 .

[3]  A. Sharon,et al.  Pathogenic and Nonpathogenic Lifestyles in Colletotrichum acutatum from Strawberry and Other Plants. , 2001, Phytopathology.

[4]  G. Hartman,et al.  Incidence of Colletotrichum spp. on soybeans and weeds in Illinois and pathogenicity of Colletotrichum truncatum. , 1986 .

[5]  James P. Martin.  USE OF ACID, ROSE BENGAL, AND STREPTOMYCIN IN THE PLATE METHOD FOR ESTIMATING SOIL FUNGI , 1950 .

[6]  P. Dixon,et al.  Influence of Temperature and Wetness Duration on Conidia and Appressoria of Colletotrichum acutatum on Symptomless Strawberry Leaves. , 2003, Phytopathology.

[7]  L. Olsen,et al.  Population Genetic Structure and Host Specificity of Alternaria spp. Causing Brown Spot of Minneola Tangelo and Rough Lemon in Florida. , 1999, Phytopathology.

[8]  L. W. Timmer,et al.  Morphological and pathological characteristics of strains of Colletotrichum gloeosporioides from citrus , 1992 .

[9]  J. Sinclair,et al.  Basic plant pathology methods , 1985 .

[10]  A. Sharon,et al.  Use of Green Fluorescent Protein-Transgenic Strains to Study Pathogenic and Nonpathogenic Lifestyles in Colletotrichum acutatum. , 2002, Phytopathology.

[11]  L. D. Ploper,et al.  The foliar fungal endophytes of Citrus limon in Argentina , 2005 .

[12]  S. Freeman.  Management, survival strategies, and host range of Colletotrichum acutatum on strawberry , 2008 .

[13]  S. Freeman,et al.  Characterization of Colletotrichum Species Causing Strawberry Anthracnose in Bulgaria , 2008 .

[14]  M. A. Soares,et al.  Evaluation of fungicide applications to sweet orange at different flowering stages for control of postbloom fruit drop caused by Colletotrichum acutatum , 2008 .

[15]  S. Sreenivasaprasad,et al.  Molecular characterization of slow-growing orange and key lime anthracnose strains of Colletotrichum from citrus as C. acutatum. , 1996 .

[16]  L. W. Timmer,et al.  Post-bloom Fruit Drop, an Increasingly Prevalent Disease of Citrus in the Americas , 1994 .

[17]  N. Peres,et al.  Lifestyles of Colletotrichum acutatum. , 2005, Plant disease.

[18]  J. P. Agostini,et al.  Population dynamics and survival of strains of Colletotrichum gloeosporioides on citrus in Florida. , 1994 .

[19]  Lilian Amorim,et al.  Colletotrichum gloeosporioides, a new causal agent of citrus post-bloom fruit drop , 2011, European Journal of Plant Pathology.

[20]  E. E. Kuramae-Izioka.  A RAPID, EASY AND HIGH YIELD PROTOCOL FOR TOTAL GENOMIC DNA ISOLATION OF Colletotrichum gloeosporioides AND Fusarium oxysporum , 2008 .

[21]  P. J. Christoffoleti,et al.  Manual de identificação e controle de plantas daninhas , 2014 .

[22]  T. Seijo,et al.  New report of Colletotrichum gloeosporioides causing postbloom fruit drop on citrus in Bermuda , 2012 .

[23]  J. L. S. Bentes,et al.  Plantas daninhas hospedeiras alternativas de Colletotrichum guaranicola em cultivos de guaraná no Estado do Amazonas , 2007 .

[24]  Laurence V. Madden,et al.  Effects of rain on splash dispersal of fungal pathogens , 1997 .

[25]  H. Corke,et al.  Molecular phylogenetic identification of endophytic fungi isolated from three Artemisia species , 2009 .

[26]  C. Baldauf,et al.  Isolation and characterization of microsatellite loci in Colletotrichum acutatum, the causal agent of postbloom fruit drop on citrus , 2011, Conservation Genetics Resources.

[27]  Bea Sommer.  Back from the Brink: Refining the Threatened Species Recovery Process , 1997 .

[28]  J. Waller,et al.  Some epidemiological aspects of post-bloom fruit drop disease (Colletotrichum gloeosporioides) in citrus , 1981 .

[29]  L. Amorim,et al.  Spatiotemporal characterization of citrus postbloom fruit drop in Brazil and its relationship to pathogen dispersal , 2014 .

[30]  D. Hartl,et al.  Principles of population genetics , 1981 .