[Fhb-update_ma] FHB Update from MD, 05/18/15

[FHB Updates - Mid Atlantic SWW Region]

There continues to be a low risk of scab in flowering wheat for all but very
susceptible varieties in Maryland. A few more days of rain could bring the
risk up for susceptible wheat as well. Continue to check this site for risk
assessment as your wheat comes into flower through the fungicide application
window (initial flower to 6 days later). I've received reports of powdery
mildew making a late resurgence in some fields, particularly in more
northern production areas. If you are considering a fungicide application at
heading for powdery mildew, it is advisable to hold off and consider one
application at early flower with scab recommended products. There are
several reasons for this: 1) the fungicides registered for scab are rated
good to very good for powdery mildew and thus one application will protect
against scab and powdery mildew damage; 2) products applied at heading that
contain strobilurins (all Quilt formulations, Headline, Twinline, Priaxor,
and Stratego) can increase the vomitoxin levels if scab does develop; and 3)
powdery mildew that develops late will primarily affect grain fill only if
it develops on the upper two leaves with the flag leaf being the most
critical. Powdery mildew generally shuts down at temperatures of 80 and
above and fully mature flag leaves are more resistant to infection through
several mechanisms. Therefore the risk of significant yield loss from a late
infection of powdery mildew is relatively low and holding off until
flowering would be effective in managing both problems.

--Arv Grybauskas, Extension Plant Pathologist, University of Maryland

For more details, go to the FHB Risk assessment tool at
http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab
Initiative, go to http://www.scabusa.org