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Mycosphaerella blight, caused by Mycosphaerella pinodes, is a destructive disease of field pea that is managed using foliar fungicides. Strobilurin fungicides have been used in western Canada for disease management since 2003. To assess the baseline sensitivities of M. pinodes isolates to the strobilurin fungicide pyraclostrobin, the effective concentration to reduce mycelial growth by 50% (EC50) was determined for 70 isolates collected prior to 2003 from Alberta, Saskatchewan, North Dakota, and Washington State. Each of these isolates was sensitive to pyraclostrobin, with EC50 values ranging from 0.03 to 0.29 mg liter−1. The pyraclostrobin concentrations required to reduce conidia germination by 50% was lower, ranging from 0.008 to 0.041 mg liter−1. In all, 324 isolates collected in 2010 and 2011 were tested for high levels of insensitivity by examining mycelial growth using a discriminatory dose of 5 mg liter−1. Nineteen isolates were highly insensitive to pyraclostrobin, with EC50 values of 80 to 216 mg liter−1. Conidia of these isolates germinated when exposed to a discriminatory dose of 0.1 mg liter−1. Insensitive isolates infected field pea plants treated with pyraclostrobin but sensitive isolates did not. The identification of insensitive isolates indicates that insensitivity may be emerging in the pathogen population.

In recent years, root rots have severely impacted yields of field pea (Pisum sativum L.) in the Canadian province of Alberta. Above-normal precipitation levels in the springs of 2011 to 2013 led to the hypothesis that Aphanomyces euteiches Drechsler may play a role in root rot in water-saturated pea fields. To determine causal agent(s) of root rot, 145 pea fields were surveyed at flowering in July 2013 (1). Symptoms of root rot were abundant; the most prominent included red vascular streaking and dark brown rot of the tap root, indicative of Fusarium spp., but brown discoloration and cortical decay of lateral roots, indicative of A. euteiches, was also observed. Total genomic DNA was extracted from diseased root samples from each field, using the Qiagen DNeasy Plant kit, and amplified with species-specific primers for A. euteiches (2). Fusarium spp. were present in all fields, but seven fields located within a 200-km radius yielded a positive reaction for A. euteiches. Five fields were re-visited in May 2014 to collect soil for a bait test (3). Tests were performed using surface-sterilized pea seeds (cv. CDC Meadow) treated with Allegiance FL (Bayer, a.i. metalaxyl) at a rate of 110 ml/kg of seed. Five seeds per pot were planted into field soils in 10-cm pots with 12 replicate pots per field. Soils were irrigated as needed until the second-node stage and then kept at saturation for 14 days. Thirty day-old pea roots were evaluated for root rot symptoms; plated onto cornmeal agar amended with metalaxyl, benomyl, and vancomycin (MBV) without surface sterilization; and visualized microscopically for presence of oospores in the roots. Roots from three out of the five field soils showed symptoms typical of A. euteiches infection, including honey-brown discoloration, degradation of the root cortex, and presence of oospores. Root rot symptoms from the remaining fields were characteristic of Fusarium root rot, and oospores were not observed in roots. Fungal cultures with fast-growing, white, aerial mycelia characteristic of A. euteiches on MBV, were recovered from roots with Aphanomyces root rot symptoms, and transferred to PDA. To confirm pathogen identity, total DNA was extracted from 7-day-old cultures growing on PDA using the Qiagen DNeasy Plant Kit. The ribosomal DNA internal transcribed spacer (ITS) region was amplified using the primer pair ITS1 and ITS4 and sequenced (4). The sequences, deposited in GenBank with accession numbers KM486065, KM486066, and KM486067, were 100% identical to the ITS rDNA sequence of several isolates of A. euteiches using a BLASTn query. Fusarium spp. were also recovered from all root samples in the soil bait test. Total DNA extracted from roots was used in PCR assays with A. euteiches-specific primers as described above. PCR amplification of root DNA was successful only from the same three fields that showed Aphanomcyces root rot symptoms, further verifying presence of A. euteiches. The inability to detect or recover A. euteiches from two fields that had tested positive in the survey was likely due to patchy distribution of this pathogen and emphasizes the importance of rigorous soil collection methods to accurately detect pathogens. Although this is the first record of A. euteiches on field pea in Alberta, the distribution of A. euteiches within a 200-km radius in southern Alberta indicates that it has likely been present in soils for several years. The interaction between A. euteiches and Fusarium spp. infection in the root rot complex of field pea and their impact on field pea production in Alberta is currently being investigated. References: (1) S. Chatterton et al. Can. Plant Dis. Surv. 94:189, 2014. (2) C. Gangneux et al. Phytopathology 104:1138, 2014. (3) D. Malvick et al. Plant Dis. 78:361, 1994. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

Core Ideas Chlormequat chloride did not markedly reduce height or lodging, but yield increased by 2% across environments. Chlormequat chloride improved barley quality through increased test weight in moderate stands (240 plants m−2). Foliar fungicides increased grain yield by 3% across environments, which overall had low disease pressure. Dual fungicide applications increased yield more than single applications only at the higher density (355 plants m−2). Greatest grain yield was achieved by 355 plants m−2, a growth regulator, and dual fungicide applications. Barley (Hordeum vulgare L.) yield has increased at a slower rate than other major crops in Alberta, and barley area has declined over the last two decades. Improved agronomic management may increase grain yield and address other production constraints such as lodging, disease, and quality limitations. Field experiments were conducted in 2014, 2015, and 2016 at four rainfed sites and one irrigated site in Alberta, Canada, to evaluate the effects of plant density (targeting 240 or 355 plants m−2), the plant growth regulator chlormequat chloride (CCC; 2‐chloroethyl‐trimethyl‐ammonium chloride), foliar fungicide application (at flag leaf, 2 wk later, or at both application [dual] timings), four rates of post‐emergence N, and the interaction of these factors on ‘Amisk’ feed barley. There was no post‐emergence N interaction with the other agronomic practices tested in this study. The CCC did not markedly reduce height or lodging, but increased grain yield by 2%. Test weight increased by 0.5 kg hL−1 with CCC at 240 plants m−2. Foliar fungicides resulted in an average yield increase of 3% in the low disease conditions encountered in the study. Dual fungicide applications increased yield over single applications at the 355 plants m−2 density only. Combined, the most intensive agronomic practices (355 plants m−2, CCC, and dual fungicide applications) provided a 7% grain yield increase compared to the low intensity control.

It is unknown if winter pea (Pisum sativum L.) and winter lentil (Lens culinaris Medik.) are feasible cropping options in Alberta. Field experiments were conducted at six locations in southern and central Alberta, Canada, between 2008 and 2012, to determine the adaptability of winter pea and lentil. Two winter pea cultivars, Specter and Windham, and one winter lentil cultivar, Morton, were seeded at three fall planting dates and three seeding rates. Spring cultivars were grown for comparison. In southern Alberta, winter pea and lentil yielded up to 39% more than spring types. The highest winter pea yield was achieved when planting was completed during the first 3 wk of September. The highest winter lentil yield was achieved when planting was completed in the second and third weeks of September. Seeding rate had little or no impact on yield; therefore, winter pea should be seeded at 75 plants m−2 and winter lentil at 110 plants m−2. Seed was analyzed to compare constituent parameters. There were minor differences in the composition of winter and spring pulses. Windham had lower starch but higher resistant starch, protein, crude fat, and ash content compared with spring pea cultivars. Specter had higher resistant starch but was similar to Cutlass for all other parameters. Morton had a higher starch content than CDC Redberry; however, starch quality was similar. Winter pulses have potential to create new and profitable opportunities for growers in the Bow Island and Lethbridge areas of southern Alberta.