[Fhb-update_cgp] FHB Update from OK, 04/26/18

[FHB Update - Central GP, Hard Winter Wheat]

Although reports of powdery mildew continue to come in from around the
state, perhaps the more important news is that other foliar diseases have
started to become active. On Apr-24, Septoria tritici blotch (Figure 1) was
prevalent on lower leaves throughout the variety trial near Walters, OK.
Walters is located in southwestern Oklahoma about 20 miles south of Lawton &
10 miles north of the Texas border. Although interesting, Septoria tritici
blotch is not the disease of concern as in this trial there also was active
leaf rust on lower leaves (Figure 2) and stripe rust on the leaves just
below the flag leaf. Dr. Brett Carver (OSU Professor/Wheat Breeder) and
Branden Watson (OSU PaSS Graduate Student) also reported active stripe rust
at various levels in trials located near Chickasha, OK in central Oklahoma
(Figure 3). The photo from Dr. Carver (the right photo in Figure 3) shows
much more severe stripe rust than was seen near Walters. These observations
indicate that both stripe and leaf rust are increasing through southern and
central Oklahoma. This activity will increase through the coming weeks as
the forecast indicates continued moisture (rains and dew) coupled with
moderate temperature. Wheat in southern Oklahoma was approaching or was
actively flowering, so the option of using a fungicide to protect yield
potential either is at hand or may be too late. Most fungicides labeled for
wheat rust control must be applied by the start of flowering (Feekes’
growth stage 10.5). The only fungicides I know of that have a label allowing
for a later application are Tilt, Quilt Xcel, and Trivapro, which can be
applied up to Feekes’ 10.5.4 (end of flowering with the kernel watery
ripe). In addition to these application deadlines, there often are required
pre-harvest intervals so you must allow for a specific number of days to
elapse between application of the fungicide and harvest. For specific
information, please consult the label for the fungicide.

--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