Progress 10/01/00 to 09/30/05
Outputs
Surveys in Brazil between 1997 and 2004 have enabled us to map the distribution of Uredo eichhorniae, a rust pathogen of waterhyacinth (Eichhornia crassipes), and record the seasonality of different spore stages of this fungus. These surveys have also enabled us to map the distribution of Uromyces pontederiae on Pontederia cordata and P. parviflora, and Eichhornia azurea. Also recorded were the distribution sites for Uromyces heterantherae on Heteranthera reniformis. Pontederia spp. E. azurea, and Heteranthese spp. are in the waterhyacinth family, Pontederiaceae, and therefore the rust fungi that attack these plants are taxonomically related to Uredo eichhorniae. Rust-infected and non-infected rooted and emergent plants from our collections were planted at the University of the State of Sao Paolo at Jaboticabal in potting soil in suitably sized buckets placed inside larger plastic pools and flooded to a height of 0.25-0.5 m of water column. The rust-infected plants
were used to culture uredospores by inoculation of new leaves as they developed and thus continuously maintain the rusts. Uredospores collected from these plants were used in cross-inoculation trials. The rust fungi on Pontederia spp. and E. azurea have been described as Uromyces pontederiae, although no details of teliospores (which are necessary for generic and specific identification of rust fungi) were provided in the original descriptions. Based on observations made in the 1960s and 1970s, C.J. Lindquist from Argentina has provided a line drawing of U. pontederiae teliospores from P. cordata var. cordata, but the information on spore morphology is nonetheles sketchy. Examination of our collections of rust fungi made it possible to compare the morphologies the spore stages from the various Pontederiaceae plants collected at different locations. These observations have provided us the first clear understanding of the morphologies of uredospores and teliospores of U. eichhorniae and
U. pontederiae. This information should enable us to re-describe the rust fungi attacking members of the Pontederiaceae.
Impacts
Waterhyacinth continues to pose problems in the southeastern United States. This project has made progress in characterizing the life cycle of a potential biological control agent, Uredo eichhorniae.
Publications
- Charudattan, R., 2005. Ecological, practical, and political inputs into selection of weed targets: What makes a good biological control target? Biological Control, 35: 183-196.
- Charudattan, R. 1999. Plant pathogens for biological control of water hyacinth - a status report. In proceedings from First Global Working Group Meeting for the Biological and Integrated Control of Water Hyacinth, St Lucia Park Hotel, Harare, Zimbabwe, 16-19 November 1998. Plant Protection Research Institute, Pretoria, South Africa, in press.
- Coelho, L., Charudattan, R., Pitelli, R.A., den Breeyen, A., and Tessmann, D.J. 2003. Host specificity of Uredo eichhorniae and taxonomic relationship of rust fungi that infect plants in the Pontederiaceae. Abstract, International Congress of Plant Pathology 2003, Christchurch, New Zealand, Feb. 2-7, 2003.
|
Progress 10/01/03 to 09/30/04
Outputs
Uredo eichhorniae Gonz.-Fragoso & Ciferri, a pathogen of waterhyacinth (Eichhornia crassipes [Mart.] Solms, Uromyces pontederiae Gerard on Pontederia cordata L. (=P. cordata L. and P. lanceolata Nutt.) and Eichhornia azurea Kunth, Uromyces heterantherae Syd. on Heteranthera reniformis R. & P., and an undescribed rust on Pontederia rotundifolia L.f. (=Reussia rotundifolia [L.f] A.Cast.) were collected during a 2-week trip to Brazil and Argentina in August 2004. Several previously surveyed sites in southeastern Brazil and the northeast of central Argentina were visited. The rust and host material collected are being examined for rust spore morphology, molecular typing, pathogenicity, and host-specificity.
Impacts
Waterhyacinth continues to pose problems in the southeastern United States. This project has made progress in characterizing the life cycle of a potential biological control agent, Uredo eichhorniae.
Publications
- No publications reported this period
|
Progress 10/01/02 to 10/01/03
Outputs
Uredo eichhorniae Gonz.-Fragoso & Ciferri, a pathogen of waterhyacinth (Eichhornia crassipes [Mart.] Solms, Pontederiaceae), was described in 1927 from the Dominican Republic, but presently it appears to have a restricted, patchy distribution in parts of Argentina and southeastern Brazil. Rust fungi attacking plants in the Pontederiaceae represent a small group of morphologically similar members whose taxonomic relationships are unknown. In addition to Uredo eichhorniae, this group consists of Uromyces pontederiae Gerard on Pontederia cordata L. (=P. cordata L. and P. lanceolata Nutt.) and Eichhornia azurea Kunth, Uromyces heterantherae Syd. on Heteranthera reniformis R. & P., and an undescribed rust on Pontederia rotundifolia L.f. (=Reussia rotundifolia [L.f] A.Cast.). Uromyces pontederiae is distributed in North and South Americas on P. cordata, whereas Uredo eichhorniae, the E. azurea form of Uromyces pontederiae, Uromyces heterantherae, and the undescribed rust
appear to be restricted to a region bounded by 20o S and 40o S. To understand the host range and taxonomic relationships of these fungi, repeated surveys were done in southeastern Brazil and the northeast of central Argentina and collections of rusts and host plants were made from several sites. The plants were cultured in an outdoor aquatic plant nursery in Jaboticabal, Brazil. The rusts were maintained on their respective hosts and uredospores collected from these plants were used in cross-inoculation trials. The results indicated that the rust accessions from E. crassipes, E. azurea, and P. cordata were specific to their respective hosts. These observations provide the first experimental proof that these fungi are distinct, host-specialized species. This information should enable redescription of the rust species attacking plants in the Pontederiaceae.
Impacts
Waterhyacinth continues to pose problems in the southeastern United States. This project has made progress in characterizing the life cycle of a potential biological control agent, Uredo eichhorniae.
Publications
- Coelho, L., Charudattan, R., Pitelli, R., den Breeyen, A. and Tessmann, D. 2003. Host specificity of Uredo eichhorniae and taxonomic relationship of rust fungi that infect plants in the Pontederiaceae. Poster, Proceedings of the 8th International Congress of Plant Pathology, Christchurch, New Zealand, 2003.
|
Progress 10/01/01 to 10/01/02
Outputs
The distribution of Uredo eichhorniae, a rust pathogen of waterhyacinth (Eichhornia crassipes) was confirmed at several locations in southern Brazil and north-eastern Argentina. In addition, these surveys have enabled us to map the distribution of Uromyces pontederiae on Pontederia cordata and P. parviflora, and Eichhornia azurea as well as Uromyces heterantherae on Heteranthera reniformis. Specimens of rust-infected plants of Pontederia spp., Eichhornia spp. and Heteranthera spp. were collected and transported to the University of the State of San Paulo (UNESP), Jaboticabal, Brazil, for further study. Infectivity, spore-germination, and cross-infectivity studies were conducted with uredospores collected from these plants. The rust infections persisted in the uredial stage survived on infected E. crassipes plants for more than 1 year. Using inoculum collected from diseased plants maintained in Jaboticabal, cross-inoculations were done according to the methodology
previously described by Charudattan et al. The results have confirmed that the waterhyacinth rust, U. eichhorniae, is host-specific to its host only. Examination of our collections have also confirmed for the first time that this rust belongs to the genus Uromyces.
Impacts
Development of experimental data to support the importation and eventual use of Uredo eichhorniae as a classical biocontrol agent for waterhyacinth is expected. Basic information on the taxonomic relationships of rust fungi that attack plants in the waterhyacinth family will be generated.
Publications
- Charudattan, R. 2001. Biological control of water hyacinth by using pathogens: Opportunities, challenges, and recent developments. Pages 21-28 in: Biological and Integrated Control of Water Hyacinth, Eichhornia crassipes. Proceedings of the Second Meeting of the Global Working Group for the Biological and Integrated Control of Water Hyacinth, Beijing, China, 9-12 Oct., 2000. ACIAR Proceedings No. 102. Australian Centre for International Agricultural Research, Canberra.
- Charudattan, R. 2001. Summary of session 3. Biological control - Pathogens: Pages 146-147 in: Biological and Integrated Control of Water Hyacinth, Eichhornia crassipes. Proceedings of the Second Meeting of the Global Working Group for the Biological and Integrated Control of Water Hyacinth, Beijing, China, 9-12 Oct., 2000. ACIAR Proceedings No. 102. Australian Centre for International Agricultural Research, Canberra.
|
Progress 10/01/00 to 10/01/01
Outputs
Distribution of Uredo eichhorniae, a rust pathogen of waterhyacinth Eichhornia crassipes, was determined through repeated surveys in southern Brazil and northern Argentina. The surveys also used to identify the potential alternate host of Uredo eichhorniae and determine the possible source(s) of aeciospore inoculum. Studies are underway to assess the biocontrol potential of this rust fungus under greenhouse and field conditions. The following host plants, with or without rust infections, were collected and transplanted in a laboratory at the University of the State of Sao Paulo, Jaboticabal, Brazil: Eichhornia crassipes - infected with Uredo eichhorniae; E. azurea - infected with Uromyces pontederiae; Heteranthera dubia - no rust was found on this plant in this trip; Pontederia cordata var. cordata (lanceolate leaves) - infected with U. pontederiae; P. cordata var. cordata (cordate leaves) - infected with U. pontederiae; and P. rotundifolia - infected with U.
pontederiae. A field site at Pocos de Caldas, Minas Gerais state and a second site at Curitiba, Parana state, Brazil, were selected for monthly monitoring of the rust cycles on E. crassipes. These sites will be used also for fungicide trials to assess the impact of the rust on the growth and productivity of E. crassipes. The rust fungi on Pontederia spp. and E. azurea have been described in taxonomic literature as Uromyces pontederiae, although no details of the teliospores were provided in the original descriptions. We examined our collections of rust-infected leaves to compare the morphologies of uredospores and teliospores from the different Pontederiaceae plants collected at different locations. These observations have provided us the first clear understanding of the morphology of teliospores of U. pontederiae from P. cordata var. cordata.
Impacts
This above information should enable us to re-describe this and other species of rusts attacking members of the Pontederiaceae.
Publications
- Charudattan, R. 2001. Biological control of weeds by means of plant pathogens: Significance for integrated weed management in modern agro-ecology. BioControl 46: 229-260.
- Charudattan, R. 2001. Biological Control of Water hyacinth by Using Pathogens: Opportunities, Challenges, and Recent Developments. Pages xxx-xxx in: Proceedings of the Second IOBC Global Working Group Meeting, Oct. 9-12, 2000, Beijing, China. In press.
- Charudattan, R. 2001. Biological Control - Pathogen: Summary of session. Pages xxx-xxx in: Proceedings of the Second IOBC Global Working Group Meeting, Oct. 9-12, 2000, Beijing, China. In press.
|
|