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United States Department of Agriculture

Agricultural Research Service

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Development of White Mold Resistant Peas

Pea lines PI 240515 and PI 169603 were identified with novel resistance to the white mold pathogen.  These pea lines are being used by the pea breeder, Alain Lecompte of Vilmorin, the fourth largest seed company in the world, and by Dr. Kevin McPhee, a dry pea breeder from North Dakota State University to develop white mold resistant pea cultivars.


Release of Six Green Pea Lines for Breeding With Outstanding Root Rot Resistant

Dr. Porter identified six pea lines with favourable horticultural characteristics (referred to as the 5000 series) that were highly resistant to Fusarium root rot and Fusarium wilts races 1, 2, and 5. The dry pea  company ProGene and green pea companies Brotherton Seed Inc., Pure Line Seed Inc., and Crites-Moscow Seed Inc. are using these lines to develop root rot resistant peas that will increase pea yields.


First Report of Chickpea Resistance to PEMV (Porter)

Significant losses in chickpea production have occurred due to the Pea Enation Mosaic Virus (PEMV) in the Palouse Region of the Pacific Northwest USA in 1990, 1996, and 2005 and can cause significant losses in other chickpea production areas throughout the world. None of the current chickpea cultivars used by growers in the Pacific Northwest have any resistance to PEMV.  Eight PI accessions from the desi-type chickpea germplasm were identified with high resistance to PEMV and one Kabuli-type had high tolerance to PEMV.  This was the first report of chickpea germplasm with resistance/tolerance to PEMV and the resistant germplasm is available to breeders to introgress resistance genes into advanced breeding lines and commercial cultivars to produce new varieties with resistance to PEMV.


Pratylenchus neglectus, P. thornei, and Paratylenchus hamatus Nematodes Causing Yield Reduction to Dryland Peas and Lentils in Idaho

First Report of Pin and root lesion nematodes impacting dry pea and lentil production in the Pacific Northwest

Pratylenchus neglectus, P. thornei, and Paratylenchus hamatus Nematodes Causing Yield Reduction to Dryland Peas and Lentils in Idaho

E. Riga, Washington State University, IAREC, 24106 N. Bunn Road, Prosser 99350; L. D. Porter and H. Mojtahedi, USDA-ARS, 24106 N. Bunn Rd., Prosser, WA; and D. Erickson, George F. Brocke and Sons Inc, Kendrick, ID


In June 2006, stunted and chlorotic plants were observed in large patches in two 40.5-ha fields of dryland peas (Pisum sativum) in Latah County, Idaho, which resulted in 90 and 75% crop loss. In the same region, a 121.4-ha field of dryland lentils (Lens culinaris) also had plants showing poor growth, wilting, and yellowing in large patches, which resulted in 40% crop loss. Two species of lesion nematodes (Pratylenchus neglectus and P. thornei) and one species of pin nematode (Paratylenchus hamatus) were extracted from rhizosphere soil and the roots of symptomatic plants from these fields. In a subsequent survey of seven dryland pea fields, under cv. Columbian, in Latah and Nez Perce counties and one dryland pea field, under cv. Small Sieve, in Latah County, plant samples had means of 551 and 2,178 mixed species of lesion nematodes per gram of dry root, respectively. Plant samples from 12 lentil fields in Latah County, six planted with cv. Red Chief and six with cv. Pardina, had means of 279 and 987 mixed species of lesion nematodes per gram of dry root, respectively. Soil samples from the same fields had a mean of 628 and 671 pin nematodes, Paratylenchus hamatus, per 250 cm3 soil for Red Chief and Pardina, respectively. Lentils cv. Pardina and peas cv. Columbian were planted separately in six pots, five seeds per pot containing 250 g of infested soil brought from the field to the greenhouse. Fumigated sandy loam soil was used as control. These assays were repeated three times. In addition, peas and lentils were planted to pots infested singly with each of the three nematode species. For this assay, nematodes were extracted from field soil, surface sterilized, and used to infest 250 g of fumigated sandy loam soil at two nematodes per gram of soil. Six plants per nematode species and an uninoculated control were used in the greenhouse assays, which were repeated three times. Nematodes in all of the assays reduced plant growth in comparison with controls; an average of 50 to 70% reduction in plant height was noted. The lesion nematode populations increased in all pots. The greenhouse assays verified the negative impact of these nematodes on growth of dryland peas cvs. Columbian and Small Sieve and lentils cvs. Red Chief and Pardina. P. neglectus, P. thornei, and Paratylenchus spp. previously have been reported from the semi-arid Pacific Northwest (1). However, to our knowledge, this is the first report attributing plant growth and yield reduction of certain cultivars of lentils and peas to these two species of lesion nematodes and pin nematodes, identified to species level as Paratylenchus hamatus.

Reference: (1) R. W. Smiley et al. J. Nematol. 36:54, 2004.



Identifying Potato Tubers with Resistance to the Late Blight Pathogen that caused the Irish Potato Famine.

I am currently screening hundreds of potato tubers for resistance to the late blight pathogen, Phytophthora infestans, in an effort to identify genes associated with the resistance.

Identifying Emerging Pathogens in Peas.

Rhizoctonia patches have developed in many pea production fields.  Dr. Porter is researching management practices such as tillage and seed treatments to try to manage this issue.  Uneven pea stands impact the overall yield and the premiums that growers receive for their fresh peas.

Identification of Metalaxyl-resistant Pythium Impacting Potato and Other Crop Production (Porter)

Several Pythium species causing leak on potato and seed rot of crops found in rotation with potatoes are managed by the systemic fungicide metalaxyl (Ridomil, Apron or Allegiance).  Soil samples from 312 fields cropped to potatoes in Idaho (140), Oregon (59), and Washington (113) were assessed for the presence of metalaxyl-resistant (MR) isolates of Pythium.  Altogether, 1.4%, 42.4%, and 32.7% of the fields from these states, respectively, were positive for MR Pythium.  The percentage of MR Pythium isolates to metalaxyl-sensitive isolates found in a field ranged from 0.9 to 92.5%.  Growers were informed of problematic fields impacting their disease management programs and alternative products are being investigated that will manage MR Pythium.

Survival of Asexual Spores of the Late Blight Pathogen in Soil (Porter)

Dr. Porter in collaborative work with Dennis Johnson (WSU) determined that the maximum length of survival of sporangia and zoospores of the late blight pathogen in soil is between 20 to 23 days under the semi-arid conditions present in the Columbia Basin.  This research provided knowledge to growers that asexual spores of the late blight pathogen do not contribute to long term survival of the pathogen, and that spores remain infectious within a 23 day window following their release from sporulating plant tissue. 


Last Modified: 3/30/2012