Start Date: May 03, 2009
End Date: May 02, 2014
Project Title 1: We will utilize both traditional dilution plating onto agar media as well as real time PCR methods to monitor the population dynamics of B. subtilis and F.graminearum on wheat heads. DON in grain will be quantified by GC/MS at VirginiaTech and correlated with observed population dynamics. We will utilize LC and MS methodologies and growth inhibition assays to identify threshold inhibitory levels of the lipopeptides produced by B. subtilis. From this research we will determine if biocontrol in this system is positively associated with threshold populations of bacteria, and we will discover how environmental conditions alter these critical levels. Finally, we will determine which and at what threshold level of the major groups of lipopeptides produced by B. subtilis are necessary for biocontrol efficacy. Project Title 2: Building on techniques perfected in New York and Virginia in 2007-2008, we will use a marked (AFLP) isolate, release-recapture experimental approach to assess relative contribution of localized clonal inocula to infection of cereal heads at the source and at more than 100 feet from the source in commercial wheat and barley fields otherwise lacking corn or cereal debris. We expect that concentrated clonal inoculum may overestimate the contribution of local inoculum to FHB and DON, so we are also employing replicated microplots in each experimental field with naturally overwintered corn debris collected from sources close to those same wheat and barley fields. The research will be conducted in two commercial-scale wheat or barley fields per season in Illinois, Missouri, Nebraska, New York, and Virginia. All field sites are in regions with considerable acreage of over-wintered corn residues nearby. Project Title 3: Two independent experiments will be conducted at the Cornell University Musgrave Research Farm in New York in 2009 so that integrated management is examined under two different cropping environments that are common in New York. One experimental environment will involve planting wheat in late September into soybean stubble. The second experimental environment will involve no-till planting of wheat into corn stubble following grain corn harvest in late October. This will provide two contrasting environments in terms of exposure to within-field inoculum (expected to be greater in corn debris) as well as to different weather conditions at the time of flowering and early grain development. The experimental design for each experiment will be a split plot, with four varieties as the whole-plots and four spray treatments as the sub-plots. There will be four replicate blocks. In each main plot within each block, there will be four randomized sub-plots of spray treatments: 1) Prosaro (6.5 fl oz/A + 0.125% Induce); 2) Bacillus subtilis TrigoCor 1448 + 0.125% Induce; 3) Bacillus subtilis TrigoCor 1448 + 0.125% Induce + Prosaro (6.5 fl oz/A); and 4) not treated. Fungicide and biocontrol application will be made at the time of early anthesis (Feekes GS 10.5.1) for each variety. Each of the four varieties chosen for two years of study is being grown commercially in New York.