[Fhb-update_cgp] FHB Update from OK, 05/17/18

[FHB Update - Central GP, Hard Winter Wheat]

Although not as obvious as in previous weeks, powdery mildew is still
hanging on in Oklahoma, and has even moved up onto the heads in some fields.
One such field is my foliar fungicide trial here at Stillwater. Examining
this trial yesterday revealed many of the lower heads were lightly to
moderately infected with powdery mildew. This is one of the few times I have
seen powdery mildew move onto wheat heads in Oklahoma. It is important to
note that these infected heads are the ones produced on the lower tillers
beneath the main, taller tillers. I did not find any powdery mildew on any
of the higher heads. This appears to me to be a light to moderate infection
severity, but I’ve not had a lot of experience with powdery mildew on
wheat heads, so this is just my estimation. Exactly how much of an impact
this powdery mildew will have on yield and test weight may be hard to
determine because the level of powdery mildew on these heads seemed to be
fairly constant across all treatments.

Yesterday, I also observed leaf rust on scattered leaves in the foliar
fungicide trial at Stillwater (mostly in the not-sprayed control plots).
Typically this was just a couple pustules scattered on a leaf. This
indicates that leaf rust is starting to appear and may increase a bit over
the next 7-10 days. However, this is a late infection as this trial is at
late milk to early soft dough. Hence, the leaf rust will have only a minimal
impact on yield even if it does increase significantly.

Finally, Brad Babek (County Educator, Washita County in southwestern
Oklahoma) reported increasing areas of white heads in wheat fields. In cases
where I have observed such heads this year, it has been due to dryland
(Fusarium) root rot. Typically the roots will be rotted and often the lowest
part of the stem is discolored (dark) and often there is a pinkish-purple
color associated with the lower tiller and roots. Splitting such a tiller
often reveals a stem filled with white or pinkish-white fungal growth.


--Bob Hunger, Extension Plant Pathologist, Oklahoma State University

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 https://www.scabusa.org