These projects involve collaboration with researchers at North Carolina State University and University of Wisconsin, and international collaborators in Costa Rica (M.S. candidate Mercedes Diaz), China (Dr. Guangyu Sun), Germany (Dr. Bernhard Oertel), The Netherlands (Dr. Pedro Crous), and Serbia (M. Sc. Tatjana Kenzević and Dr. Radivoje Jevtic).Postdoctoral researcher Dr. Jean Batzer is leading projects to 1) characterize the range of genetic diversity in SBFS fungi in the U.S. and 2) identify SBFS fungi to species. In collaboration with Dr. Tom Harrington, Jean has identified >30 new fungi in the SBFS complex in the Upper Midwest (Iowa, Illinois, Missouri, and Wisconsin) using PCR of the ITS and LSU regions of rDNA followed by sequencing and parsimony analysis (Mycologia 2005: http://www.mycologia.org/cgi/content/full/97/6/1268). This work dramatically changed the previous view of the extent of diversity in the SBFS complex and opened many new avenues for research. Jean is also investigating how heterogeneity of wetness duration within apple-tree canopies can affect performance of a SBFS warning system, developed in NC and KY, that uses wetness duration to save fungicide sprays.
In collaboration with Dr. Pedro Crous of CBS, Utrecht, The Netherlands, Jean is currently identifying sub-groups of the U.S. SBFS fungi. In cooperation with Drs. Bernhard Oertel and Thomas Feldmann of the University of Bonn, Germany, Jean is helping to identify SBFS islolates from German orchards using DNA and morphological description.
Katie Duttweiler, a M.S. candidate, is evaluating an RFLP-based method to streamline identification of SBFS fungi. This technique could open the door for ecological and management studies by allowing researchers to identify SBFS fungi directly from mycelium scraped off apple peels, avoiding cumbersome and time-consuming agar plate bioassays. Katie is also gathering weather data and SBFS occurrence data from orchards in Iowa, North Carolina, and Wisconsin to refine the existing SBFS warning system.
Mercedes Diaz, a M.S. candidate at University of Costa Rica, is doing her M.S research on SBFS in our lab. She is examining the diversity and biogeography of SBFS fungi in the eastern U.S. Using colonies isolated from apples in 30 orchards across 10 eastern U.S states, Mercedes is describing SBFS genetic diversity in the region by parsimony analysis of sequences from the ITS and LSU regions of rDNA, and characterizing morphology of these isolates.
Two undergraduate research interns mentored by Jean Batzer in 2005-2006, Fabien LeCorronc (ESMISAB, Brest, France) and Benjamin Peterson (ISU), conducted in vitro studies of growth and morphological responses of a wide range of SBFS fungi to nutrition (percent apple juice). This information will be combined in a manuscript with studies on in vitro temperature responses by the same fungi, conducted by former M.S student Sandra Hernández (graduated 8/05) and our collaborator, Dr. Patty Mc Manus of the University of Wisconsin. New projects on SBFS include an investigation of the timing of appearance of colonies of various SBFS fungi on apples in Iowa orchards (by M.S. student Adam Sisson), and speciation of SBFS fungi in the genus Pseudocercosporella (by M.S. student Nenad Tatalović).
A 2-year (2006-2007) field project, in collaboration with Dr. McManus, is exploring the impact of apple tree pruning and fungicide-spray volume on SBFS suppression when using the SBFS warning system to extend the spray interval between first and second cover. In addition, Nenad Tatalović will evaluate the effectiveness of remotely estimated wetness-duration data (SkyBit, Inc.) for implementing the SBFS warning system during the 2006-2008 growing seasons.
A collaboration with Dr. Guangyu Sun, a fungal geneticist at Northwest Sci-Tech University, Yangling, People's Republic of China, began in 2002. After isolating SBFS fungi from apples in commercial orchards in Shaanxi Province in central China, Dr. Sun's team is performing PCR and sequencing of the ITS and LSU regions of these isolates. We will then attempt to fit Dr. Sun's SBFS assemblage into the phylogenetic trees created by Jean Batzer for the Midwest U.S. One publication has already emerged from this collaboration (Sun et al., 2006, Mycotaxon 95:277-280).