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

[FHB Update - Central GP, Hard Winter Wheat]

Nearly all of the wheat I saw this past week was along a line for about 100
miles west of Stillwater. Wheat around Stillwater is at the milk to soft
dough stage. Wheat west of Stillwater ranged from full kernel to full
kernel-milk. In this area, I saw both good and bad wheat. Much of the bad
wheat I saw had been hit with wheat streak mosaic (WSM). To date, the Plant
Disease and Insect Diagnostic Lab (Ms. Jen Olson, Director) has assessed
about 82 wheat samples from 19 counties for Wheat streak mosaic virus
(WSMV), High plains virus (HPV), and Barley yellow dwarf virus (BYDV; PAV
strain). These 19 counties are located west of Stillwater, and mostly are
west of I-35. Of these 82 samples, 56 were positive for WSMV, 11 were
positive for HPV (all 11 co-infected with WSMV), and 42 were positive for
BYDV. Four of the samples were positive for all three viruses. These figures
indicate the severity of wheat viruses in Oklahoma this year. Reports from
other states indicate this problem (mite transmitted viruses such as WSM) is
just as severe up through the central plains. The cool, wet weather we have
had can mitigate the effects of WSM and BYD, and help infected plants to
continue to mature and finish. This would be especially true for
plants/fields that were infected in the spring. However, yield and test
weight will be affected especially if wheat was infected in the fall. For
more information on mite-transmitted wheat viruses such as WSM, please see
OSU Fact Sheet EPP-7328 (Wheat Streak Mosaic, High Plains Disease, and
Triticum Mosaic: Three Virus Diseases of Wheat in Oklahoma) available at
http://pods.dasnr.okstate.edu/docushare/dsweb/HomePage

Regarding leaf and stripe rust, I have seen mostly leaf rust over the last
week, but signs of stripe rust (both active and inactive) also can be
observed. On susceptible varieties that were not sprayed, leaf rust was
severe (≥60% flag leaf area showing pustules). In his nurseries at Lahoma
in north-central OK, Dr. Brett Carver (OSU Wheat Breeder) is seeing some
active and inactive stripe rust. Given our cool and wet weather, stripe rust
appears to be re-activating. Dr. Carver also is seeing abundant and severe
leaf rust.


--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