Annual Progress Report on Malting Barley Research March, 2002

8
All field observations have been forwarded to the USDA-ARS laboratory at Aberdeen,
Idaho and entered into the GRIN system.
Discussion and Recommendations
In the Toluca Valley of Mexico, the environmental conditions continue to be conducive
to disease development. In 2001 the high level of natural inoculum continued to be
conducive to disease occurrence and provided good pathogen pressure and subsequent
disease development. Susceptible controls showed a very high degree of infection (100%
in many instances) while the newly released Brancroft (being used as a resistant check)
was generally resistant or, at most sustained a trace of rust.
In the Huancayo Valley the environment was also conducive to development of high
inoculum pressure and disease development. In Callejon de Huaylas 56.3% of the entries
were in the infection type range of 0. This could possibly be due to escapes resulting
from heavy rains and high levels of Helminthosporium teres damage.
The differences in infection type in the same entries in Huancayo, Callejon de Hualas in
Peru and the Toluca Valley in Mexico are very likely due to the presence or emergence of
different BSR races.
The percentage of lines with resistance to BSR from all sources has consistently proved
to be higher than prior years. These lines are essentially the result of the successful
identification and selection by the participating breeders in the various programs. Over
the years this rapid field-screening program has quickly identified lines of varying levels
of resistance. Also, the program has consistently proved to be an effective method for
rapid identification of resistance sources.
While significant progress has been made identifying barley stripe rust resistance, there is
still a major problem in developing agronomically acceptable reliable resistant lines for
deployment in the near future. This is especially clear this year with the high levels of
susceptibility shown at the Hyancayo site in lines that exhibit resistance at the other sites.
While there are more commercially available lines with sufficient levels of resistance to
BSR and the essential qualities necessary for a good malting barley, the breakdown of
resistance as typified by Bancroft and other lines at Hyancayo (refer to GRIN data for
specific lines) again demonstrates the diversity of the stripe rust populations.
The winter nurseries were planted in December 2001 at both locations in Peru. As noted
above these sites provide excellent alternative season (winter) locations for further
screening to develop germplasm in an accelerated manner.
Acknowledgements
Dr. Hugo Vivar and Dr. Flavio Capitini (Dr. Vivar’s replacement) CYMMIT, Mexico
for field management of the trials.
Dr. Luz Gomez Pando, Head, Programa de Cereales y Leguminosas, Universidad
Nacional Agraria La Molina, Lima, Peru for field management and cooperation In the
Peruvian winter nursery.
Dr. Darrel Wesenberg and Dr. Harold Bockelman at the USDA/ARS Small Grains
Laboratory, Aberdeen, ID for providing and preparing barley lines used in this program.