Annual Progress Report on Malting Barley Research March, 2002

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assessments were made by counting the percentage of FHB infected spikelets on 20
heads per plot. FHB incidence (FHBI) was measured as the percentage of infected spikes
of the twenty that were assessed. FHB severity (FHBS) per plot was then derived as the
product of FHBI and FHB severity of infected spikes. Discolored kernels were measured
as the percentage of seed that were obviously discolored compared to normal bright
colored barley from a 100-seed sample from each plot. Deoxynivalenol concentration
(parts-per-million, ppm) in grain was determined following procedures established by
Mirocha et al. (1998; J. Agric. and Food Chem., 46:1414-1418).
In 2000 mean FHBI was 25, 36, 50, and 75 (l.s.d.0.05=18) without MI for the barleys
MNS 93, MNBrite, Robust and Stander, respectively. The high FHBI for MI treatments
of 2-8 mm per day for barley readily confirmed MNS 93 to be more resistant than the
other barleys. Differences of FHBS were significant for barley but differences among
entries were less variable at the no-mist and 2 mm MI treatments. Differences of FHBS
were pronounced between MNS 93 and Stander barley over all MI volume treatments
and no different between Robust and MNBrite. Differences among the barley entries for
the percentage of discolored kernels were most apparent at 2 and 8 mm volume
treatments. Differences of deoxynivalenol (DON) concentration in grain among the four
barley cultivars were consistent over each of the mist-irrigation treatments.
Differentiation among susceptible and resistant barley cultivars was possible under the
no-mist treatment for FHBI. Drier weather in 2001 diminished our ability to differentiate
barley entries. Differences among barley cultivars for FHBS were apparent over the four
MI treatments tested and was clearest for discolored kernels at the highest MI treatment.
These preliminary data suggest that reducing mist-irrigation volume does not inhibit
investigators from differentiating resistant and susceptible germplasm. Reducing MI
volume could also minimize the likelihood of inducing too severe FHB levels. This
would then facilitate the production of higher quality seed within breeding lines that are
less severely infected with FHB and provide higher quality seed for later experiments.
These data also demonstrate that investigators are not necessarily bound to locations with
irrigation facilities. Useful information could be obtained by inoculating plots in
locations without water thus increasing the number of locations that could be utilized to
screen promising germplasm. Lower disease severity conditions may more realistically
reflect conditions observed in farmers’ fields as well. Additional studies are underway to
further examine the effects of reducing mist-irrigation in FHB screening nurseries.
Plant Pathology Research on other Barley Diseases
This program also provides support to the barley breeding program as part of ongoing
breeding efforts to develop improved germplasm with improved disease resistance.
Screening breeding germplasm for resistance to kernel discoloration, leaf rust, loose
smut, net blotch, powdery mildew, and spot blotch are conducted on an ongoing basis
with the barley breeding program.
In 2001 evaluations were conducted to identify resistant germplasm in breeding
populations following natural infections of leaf spot diseases at the Northwest Research
and Outreach Center, Crookston and the West Central Research and Outreach Center,