2012 Dryland Field Day Abstracts - Dept. of Crop and Soil Sciences ...

Part 2. Pathology and Entomology Page 37
alternative host plants for both the virus and aphid.
Email listservs are used to alert farmers and crop consultants of aphid infestations and whether they carry virus – which greatly
influences potential damage to legume crops and the aphid population levels at which growers should apply insecticide. This
information is also posted to the Aphid Tracker website at http://www.cals.uidaho.edu/aphidtracker/index.asp.
2) Decision Tools: We have developed the first research-based economic injury level for pea aphid in pea crops on the Palouse. In
addition, 5 years of field survey results were used to estimate the spatially variable character of disease prevalence on the
landscape, as well as a region-wide estimation of aphid density based on historical meteorological data and an index of aphid
abundance from 1986-2006. These elements have been incorporated into online tools to help producers decide about seed
treatments and early season sprays for aphid control.
Online calculators have been constructed from these data:
The first calculator helps growers decide on treatments for pea seed.
The second calculator helps growers decide whether to spray their fields early for aphid.
The third calculates an Economic Injury Level for aphids pre-bloom.
3) Accelerated Breeding for Virus Resistance in Pea and Lentil: Plant breeders at North Dakota State University are developing pea
and lentil varieties with resistance to PEMV and BLRV, using marker-assisted selection to augment the breeding process. They are
also improving diagnostic tools that verify virus presence and disease reaction. These varieties will be useful additions to
forecasting and decision tools to help reduce the severity of virus outbreaks.
Mutation Breeding of Cultivated Barley and Screening of Wild Barley for Resistance to Rhizoctonia
Root Rot
O. Ajayi, S. Ullrich, T. Paulitz, K. Campbell and K. Murphy; Dept. of Crop and Soil Sciences, WSU and USDA-ARS
Rhizoctonia root rot and bare-patch caused by Rhizoctonia solani G-8 is one of the most important diseases that limit crop yields in
no-till/direct seeding systems in the Pacific Northwest (PNW), and in turn, limiting the widespread adoption of this system in this
region. But in the PNW, spring cropping with no-till/direct seeding offers a potentially better approach to increasing cropping
intensity and circumventing the negative impacts tillage has on the environment, mainly on soil and water due to erosion. However
for spring barley, an important rotational crop with winter wheat, peas and lentils, Rhizoctonia root rot appears to be the most
important disease under direct seeding systems. The role of barley as a rotational crop highlights the possibility for its use in
managing the disease if resistant barley cultivars are included in the normal 2-3 year rotations with winter wheat under reduced
tillage in any growing environment. Furthermore, it has been shown that barley in rotation with winter wheat improves the
productivity of winter wheat. Therefore, the objective of our research is to identify potential sources of resistance to R. solani AG-
8 in barley. Since there is no known resistance in the natural populations of barley available to breeders, we employed two
approaches to achieve the set objective. Firstly, we employed induced mutation as a means of creating new genetic variation. The
first experiment involved screening sodium azide barley mutants for disease reaction to R. solani AG-8, verifying the resistance in
putative mutants, and carrying out genetic analysis to determine the mode of inheritance of resistance to the pathogen. Ten
putative M3 individuals from 2 different barley lines, 05WA-316.99 and ‘Lenetah’ have been verified for resistance and crosses have
been made to the wild type to begin inheritance studies. Secondly, given the importance of wild crop relatives to crop
improvement, our second experiment involved exploring the possibility of identifying resistance to the disease in the direct
progenitor of cultivated barley Hordeum vulgare subsp. spontaneum. Of the entire pool of 316 accessions in the Wild Barley
Diversity Collection that was screened for resistance, 6 accessions showed potential as gene donors for Rhizoctonia resistance with
one accession, WBDC 021 showing the greatest potential based on the disease ratings and other growth parameters measured.
Further testing is currently being carried out to verify the resistance of these accessions to R. solani AG-8 and also to R. oryzae,
another pathogen known to cause root rot of wheat and barley and found with R. solani AG-8 in production fields. The overall goal
is to release resistant barley cultivars to farmers in the PNW, thereby, providing a more sustainable and environmentally sound
means of managing the disease.