[Fhb-update_cgp] FHB Update from OK, 05/31/19

[FHB Update - Central GP, Hard Winter Wheat]

Harvest in southern OK started just this week, so this report will focus
primarily on wheat in central, northern, northwestern and the panhandle of
Oklahoma. It appears that the wheat crop is well along in its development
and needs some dry and warmer weather to finish (as well as to allow
harvest!). The primary issues this past week have been deterioration of
leaves and head discoloration. The wet environment certainly is contributing
to both of these issues. In wheat around Stillwater, heads are being
discolored due to black chaff (a bacterial disease) as well as
Septoria/Stagonospora that cause leaf spotting as well as head
discoloration. There also is a general darkening of heads, called melanism,
which results not from a disease but rather is related to genetics and
environment. This melanism is difficult to distinguish from the other
diseases that are present, especially because this year there seems to be
all these happening at once.

Other diseases that are likely to be observed at this point in time are
white heads due to foot rots (see wheat disease update on 5-24-2019
available at http://entoplp.okstate.edu/pddl/advisory.htm), Fusarium head
blight, and sooty mold. I’ve described and discussed Fusarium head blight
in a previous update (5-16-2019 available at
http://entoplp.okstate.edu/pddl/advisory.htm). Sooty mold on heads occurs
when wheat has turned but cannot be harvested in a timely manner. Wet and
humid conditions promote fungal growth on those heads (Figure 4). With time,
these fungi can also partly start to grow on wheat seed still in the head,
especially at the germ end of the seed. This can lead to a poorer quality of
wheat and reduced seed germination

What is described above is confirmed for northwestern OK and the OK
panhandle by Josh Bushong (NW OK Area Extn Agron Speclt) who reported seeing
overall leaf health as deteriorating across NW OK as well as at field days
this past week at Hooker, Balko and Goodwell (all in the OK panhandle).
However, the wheat in these parts of Oklahoma should be sufficiently far
along (mostly in dough stage) so that the impact on yield should be minimal.
Be aware though that head diseases such as Fusarium head scab and sooty mold
can affect grain quality and create major problems when the wheat is taken
to the elevator.


--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