Gary Bergstrom, Extension Plant Pathologist, Cornell University
Winter wheat development in New York ranges from Feekes growth stage 8 (flag leaf just visible) to stage 10 (in boot). Plants currently in boot should begin to flower in the next week or so with daily high temperatures predicted to be in the 70s. Only minor levels of powdery mildew and fungal leaf blotches have been observed in lower wheat canopies and upper leaves are generally free of disease symptoms. No rust has been sighted yet in New York. Note that fungicide products containing strobilurins should not be applied after flag leaves have emerged in order to avoid a risk of elevated levels of the mycotoxin deoxynivalenol (DON). Most New York wheat producers will make a critical decision in the next week on whether to make a single application of triazole fungicide at the onset of flowering (Feekes stage 10.5.1), coinciding with the principal infection period for Fusarium head blight (FHB). The triazole fungicides Caramba, Prosaro, and Proline have shown the greatest efficacy in suppression of FHB and reducing the potential for mycotoxin contamination in grain. These materials when applied at flowering also provide very good protection against powdery mildew, rust, and fungal leaf blotches during the critical early grain-filling period. We have experienced moist conditions recently that favor production of Fusarium spores on corn and small grain crop residues, but moisture must also be present on wheat heads at flowering for significant infection to occur. It appears that the earliest planted wheat may begin to flower during a fairly dry period, but that forecast could easily change over the next week. Growers are urged to consult the FHB Risk Assessment Tool and State Commentary frequently as their crop approaches flowering.
For more details, go to the FHB Risk Assessment Tool at http://www.wheatscab.psu.edu/riskTool_2012.html
