ASSURING LONG TERM PRESERVATION OF TROPICAL CROPS VIA GENETIC RESOURCE MANAGEMENT
Title: IDENTIFICATION AND CHARACTERIZATION OF PESTALOTIOPSIS SPP. CAUSING SCAB DISEASE OF GUAVA, PSIDIUM GUAJAVA L. IN HAWAII
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2005
Publication Date: January 20, 2006
Citation: Keith, L.M., Velasquez, M., Zee, F.T. 2006. Identification and characterization of pestalotiopsis spp. causing scab disease of guava, psidium guajava l. in Hawaii. Plant Disease, 90:1, pp. 16 - 23.
Interpretive Summary: Guava, which is commonly processed into puree and juice, is affected by many fruit rot diseases. Guava is grown at the USDA/ARS Tropical Plant Genetic Resource Management Unit in Hilo, Hawaii. The fields were surveyed for common disease symptoms and the fungi causing disease were isolated and identified. Typically observed leaf and fruit symptoms were documented. The fungi isolated were examined and compared using a variety of techniques.
Guava is one of the most widely grown and propagated plants in the tropics; however, it is associated with many fruit rot diseases. Because guava is commonly processed into puree and jiuce, fruit diseases can decrease its marketability. A survey of scab disease was conducted at the USDA/ARS Tropical Plant Genetic Resource Management Unit in Hilo, Hawaii where over 50 accessions of guava are grown. Symptoms observed were grey/light brown lesions surrounded by dark brown borders on leaves and brown, raised, corky, necrotic lesions on the exocarp of fruit which progressed as the fruits matured. Seventeen isolates from infected fruit, six isolates from lesions on leaves, and nine isolated from symptomatic leaves and fruit was Pestalotiopsis spp. Morphology, colony characteristics, and pathogenicity of the isolates were examined and potential sources of host resistance were identified for germplasm characterization studies. Molecular methods were used to identify four Pestalotiopsis spp. (P. clavispora, P. microspora, P. sp. GJ-1, and P. disseminata) on guava in Hawaii. To our knowledge this is the first report of traditional and molecular methods of identification and characterization being used for guava pathogen interaction studies in Hawaii. The importance of Pestalotiopsis as a guava pathogen and its cross-infection potential are discussed.