International trade in ornamental plants has increased worldwide. Dracaena is the genus most frequently imported into the United States and many pests and pathogens currently not in the United States could be imported with Dracaena plant materials. In 2009, lucky bamboo (Dracaena sanderiana) with anthracnose symptoms was found in Florida. The associated fungus, putative Colletotrichum dracaenophilum, is considered a reportable pathogen that originated from Asia. Imported D. sanderiana plants with anthracnose symptoms were collected from a nursery in south Florida in 2011 and retail stores in north Florida in 2012 and 2013. Five isolates of Colletotrichum spp. were isolated from symptomatic D. sanderiana plants and Koch’s postulates were fulfilled for the first time. Polymerase chain reaction was performed on the internal transcribed space (ITS) and 28S rDNA regions of three original isolates and re-isolates and these sequences were compared with sequences of Colletotrichum spp. in GenBank. Sequence analysis indicated that the Colletotrichum isolates obtained from D. sanderiana in Florida belonged to C. dracaenophilum or the C. gloeosporioides species complex. Latent infections on healthy-looking lucky bamboo developed anthracnose lesions within 2 to 3 months. The reaction of several Dracaena species and varieties to the two Colletotrichum species was tested. Colletotrichum dracaenophilum caused the most severe disease on lucky bamboo, whereas one isolate of the C. gloeosporioides species complex was least pathogenic to all of the Dracaena spp. and varieties. Hot water treatments were not effective at controlling latent infections, but application of Azoxystrobin at 0.075 g a.i./L significantly reduced anthracnose development on both latently infected and inoculated lucky bamboo plants.
Kalpana Sharma, Joyce L. Merritt, Aaron Palmateer, Erica Goss, Matthew Smith, Tim Schubert, Robert S. Johnson and Ariena H.C. van Bruggen
Joyce L. Merritt, Ellen Dickstein, Robert S. Johnson, Michael Ward, Robert J. Balaam, Carrie L. Harmon, Philip F. Harmon, G. Shad Ali, Aaron J. Palmateer, Timothy Schubert and Ariena H.C. van Bruggen
The purpose of this study was to evaluate the U.S.-Canadian Greenhouse Certification Program (USGCP) that was initiated in 1998. A survey consisting of 34 questions was designed and 43 out of ≈48 nurseries in Florida participating in the USGCP were visited. Based on the answers to the questionnaire, most of the nurseries were in compliance with the majority of USGCP requirements, growers were satisfied with the program, and there was an economic benefit to participating in the program. The main problems identified were the ambiguous wording of some of the requirements and the impracticality of keeping imported and domestic plants completely segregated. Moreover, many of the respondents did not have a written description of a pest management plan. Chi square statistical analysis showed that there was almost no difference between nursery groups in their responses to the majority of the survey questions, indicating that the USGCP is a successful program for both large and small nurseries. This quantitative assessment of the USGCP is the first assessment conducted for this program and discussed in a peer-reviewed publication.