Annual Progress Report on Malting Barley Research March, 2002

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were resistant to all six diseases. These accessions have been crossed to a susceptible
malting barley cultivar to study the genetics of multiple disease resistance.
Evaluation of H. vulgare × H. bulbosum recombinants. Dr. Richard Pickering of Crop
and Food Research in New Zealand has established a world-renown gene introgression
program to develop H. vulgare × H. bulbosum recombinants. We routinely screen
recombinants developed by Dr. Pickering for disease resistance. FHB data were obtained
on 26 introgression lines planted in China. Only two lines (38P18/22/3 and 219W3)
exhibited less than 10% FHB incidence and severity under light disease pressure. It is
not known whether the lower disease severity in these lines was due to the H. bulbosum
introgression because the H. vulgare parent also exhibited relatively low disease levels.
Further evaluation tests are planned to assess the FHB resistance and DON accumulation
of these recombinants.
Barley disease survey. A survey was made in the northwestern part of Minnesota (the
primary barley production area in the state) to ascertain the prevalence and importance of
barley diseases in 2001. Eleven fields were visited during the survey conducted on July
24-26. FHB and net blotch were detected in every field; the observed severities ranged
from trace to 4% and trace to 80%, respectively (Table 1). Stem rust, SSLB, and loose
smut were the next most common diseases observed in commercial fields. Other diseases
identified in the survey (listed in decreasing order of prevalence) were crown rust, barley
yellow dwarf, and bacterial blight. Net blotch has been and continues to be a major
disease problem on six-rowed barley in the region. FHB and SSLB have historically
been minor diseases of barley in the Upper Midwest. However, since 1993, these
diseases have increased significantly in importance, and epidemics have occurred in some
regions of the state. It is not uncommon to find loose smut in Minnesota barley fields,
but the incidence is usually very low. Producers who save seed from the previous year’s
crop often have higher levels of loose smut in their fields. Crown rust, barley yellow
dwarf, and bacterial blight are common diseases in Upper Midwest barley fields—the
severity of each disease in any one year can vary dramatically. For example, barley
yellow dwarf is usually found in trace amounts in just a few fields each year. However,
in 1999, a severe epidemic occurred, and the disease was found in over 80% of fields and
in severities of up to 50%.
Collecting and maintaining a library of pathogen isolates. It is essential to keep a
library of characterized pathogen isolates to conduct disease evaluation tests of breeding
material and other germplasm. Additional isolates of F. graminearum, P. t. f. teres, C.
sativus, and P. g. f. sp. tritici were collected during the 2001 barley disease survey.
These isolates were purified and then stored for future virulence evaluations.
Additionally, eleven isolates of P. hordei were received from cooperators around the
United States in 2001. Due to severe insect infestations in the greenhouse, none of the
isolates was successfully increased.
Evaluation of barley breeding germplasm for resistance to foliar disease. One
hundred and forty-four barley lines from the University of Minnesota Barley
Improvement Program were inoculated with the spot blotch pathogen in the field at St.
Paul. This evaluation was done to ensure that the durable spot blotch resistance in sixrowed
germplasm was maintained in populations derived from non-elite parents.