Ergot: a perennial issue?

Non-Peer Reviewe

Seedling diseases, insects, and seed treatments

Non-Peer Reviewe

Development of a quick and reliable molecular detection system for Sclerotinia stem rot of canola in western Canada

Non-Peer ReviewedSclerotinia stem rot is an important, yield-limiting disease of canola caused by the necrotrophic fungus Sclerotinia sclerotiorum. The development of stem rot is highly dependent on environmental conditions and inoculum levels, and as a result disease occurrence and severity are sporadic in nature. In western Canada, stem rot is primarily controlled through the routine application of fungicides, which are often applied with no indication of disease risk. In order to reduce non-economical application of fungicides, a reliable forecasting system is needed. Since the infection of canola petals in an important step in the stem rot disease cycle, a quantitative (q)PCR-based system that can give an estimate of petal infestation rates could form the basis of a reliable forecasting system to help guide fungicide spray decisions. A primer and TaqMan probe have been developed based on the sequence of a novel protein that is specific to S. sclerotiorum. This primer-probe system, when used in a TaqMan qPCR assay, can quantify S. sclerotiorum DNA with a high level of sensitivity and specificity. The development of an internal amplification control will further increase the reliability of the assay by accounting for false negatives. This assay shows great potential for use as the basis of a stem rot forecasting system for canola in western Canada

Spot Form of Net Blotch Resistance in a Diverse Set of Barley Lines in Australia and Canada.

The responses of 95 barley lines and cultivars to spot form of net blotch (SFNB) caused by Pyrenophora teres f. maculata were analyzed as seedlings and adults in Australia and Canada. Cluster analyses revealed complex reaction responses. Only 2 lines (Esperance Orge 289 and TR3189) were resistant to all isolates at the seedling stage, whereas 15 lines and cultivars (81-82/033, Arimont, BYDV-018, CBSS97M00855T-B2-M1-Y1-M2-Y-1M-0Y, C19776, Keel, Sloop, Torrens, TR326, VB0111, Yarra, VB0229, WI-2477, WI2553, and Wisconsin Pedigree) were resistant toward the two Canadian isolates and mixture of Australian isolates at the adult stages. In Australian field experiments, the effectiveness of SFNB resistance in three barley cultivars (Barque. Cowabbie, and Schooner) and one breeding line (VB9104) with a different source of resistance was tested. Barque, which possessed a resistance gene that provided complete resistance to SFNB, was the most effective and showed no effect on grain yield or quality in the presence of inoculum. Generally, cultivars with seedling or adult resistance had less disease and better grain quality than the susceptible control. Dash, but they were not as effective as Barque. A preliminary differential set of 19 barley lines and cultivars for P teres I. maculata is proposed

How much phosphorus do crop residues release under conventional and zero tillage systems?

Non-Peer ReviewedIn a field experiment conducted at Fort Vermilion in north-western Alberta, we used the litter bag method to quantify phosphorus (P) release from red clover green manure, field pea, canola and wheat residues under conventional tillage and zero tillage. Wheat residues added significantly less P (1.7 kg ha-1) to the soil than the other residues (5.6-8.5 kg P ha-1). Tillage had no significant effect on residue P applied, but the trend was for slightly greater amounts under ZT than under CT. Clover released the most P (3.8 kg ha-1 under CT and 2.8 kg ha-1 under ZT, compared with 1.4 kg ha-1 or less from the other residues). There were no significant tillage effects on the amounts released by clover, pea and canola residues, but wheat immobilized 0.2 kg P ha-1 under ZT compared with 0.4 kg P ha-1 released under CT. Soil phosphate contents were not significantly different between tillage systems. Phosphate contents decreased with soil depth, especially under ZT. However, there was no tillage by soil depth interaction with canola residues, where soil phosphate was greater (although not significantly) under ZT than under CT at all depths. Uptake of P by wheat was significantly greater where pea and, to a lesser extent, canola residues had been applied than where clover and wheat residues had been applied, and tillage had no significant effects on P uptake

Management of leaf spotting diseases of winter wheat in western Canada

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Managing blackleg of canola – potential new tools

Non-Peer Reviewe

Rotational diversity effects in a triticale-based cropping system

Research indicates that not all crops respond similarly to cropping diversity and the response of triticale (× Triticosecale ssp.) has not been documented. We investigated the effects of rotational diversity on cereals in cropping sequences with canola (Brassica napus L.), field pea (Pisum sativum L.), or an intercrop (triticale:field pea). Six crop rotations were established consisting of two, 2-yr low diversity rotations (LDR) (continuous triticale (T-T_LDR) and triticale-wheat (Triticum aestivum L.) (T-W_LDR)); three, 2-yr moderate diversity rotations (MDR) (triticale-field pea (T-P_MDR), triticale-canola (T-C_MDR), and a triticale: field pea intercrop (T- in P_MDR)); and one, 3-yr high diversity rotation (HDR) (canola-triticale-field pea (C-T-P_HDR)). The study was established in Lethbridge, Alberta (irrigated and rainfed); Swift Current (rainfed) and Canora (rainfed), Saskatchewan, Canada; and carried out from 2008 to 2014. Triticale grain yield for the 3-yr HDR was superior over the LDR rotations and the MDR triticale-field pea system; however, results were similar for triticale-canola, and removal of canola from the system caused a yield drag in triticale. Triticale biomass was superior for the 3-yr HDR. Moreover, along with improved triticale grain yield, the 3-yr HDR provided greater yield stability across environments. High rotational diversity (C-T-P_HDR) resulted in the highest soil microbial community and soil carbon concentration, whereas continuous triticale provided the lowest. Net economic returns were also superior for C-T-P_HDR ($670 ha–1) and the lowest for T-W_LDR ($458 ha–1). Overall, triticale responded positively to increased rotational diversity and displayed greater stability with the inclusion of field pea, leading to improved profitability and sustainability of the system

Assessing the genetic and pathogenic variability of Pyrenophora teres f. maculata (spot form net blotch of barley) and its ability to overcome currently-used sources of resistance on the Canadian prairies

Non-Peer ReviewedEighty two isolates of the fungus Pyrenophora teres f. maculata, causal agent of spot form net blotch (SFNB) of barley, were collected across the Canadian prairies. Following genetic analysis using 13 microsatellite DNA markers, 27 isolates were selected to assess the degree of pathogenic variation in the fungus. Pathogenic variability was evaluated by inoculating isolates onto 11 barley genotypes as differential hosts at the seedling stage. One week following inoculation, the second and third leaves of each plant were rated on to a 1–9 disease severity scale, and plants with scores of 1–3 and >3 were scored as resistant and susceptible, respectively. The entire experiment was repeated. Cluster analysis revealed 13 distinct pathotype groups (virulence patterns) among the 27 representative isolates. Disease severity ratings ranged from 2.2 to 6.1 with a mean of 4.6. To assess the risk of resistance breakdown, the resistance of four barley cultivars (‘AAC Synergy’, ‘CDC Meredith’, ‘Cerveza’ and ‘Major’), which had been previously identified as resistant to SFNB on the Canadian prairies, was evaluated at the seedling stage against six isolates of P. teres f. maculata representing four different pathotypes. The resistance in ‘CDC Meredith’ was clearly overcome by all isolates tested, while ‘AAC Synergy’, ‘Cerveza’ and ‘Major’ still exhibited resistance against all of the pathotypes. The identification of fungal isolates virulent on ‘CDC Meredith’ suggests that producers should avoid growing the same resistant barley variety in short rotation, and avoid relying on resistance as the sole approach to disease management. Judicious use of fungicides, coupled with rotations of at least two years between barley crops and diversity in the barley varieties grown, will promote effective and sustainable management of spot form net blotch

Economics of preceding crops and nitrogen application rates for canola and barley production in western Canada

Non-Peer ReviewedThe objective of this study was to evaluate the economic effects of a range of legume and non-legume preceding crops and N rates on costs and net revenue (NR) of canola (Brassica napus L.), barley (Hordeum vulgare L.) and canola-barley rotation under various environmental conditions. Legumes such as field pea (Pisum sativum L.) and lentil (Lens culinaris Medik.) as preceding crop generated higher net revenues for the following crops canola and barley than when wheat (Triticum aestivum L.) and canola were the preceding crops. Although faba bean (Vicia faba L.) grown as a green manure produced the highest annual net revenues for the following crops canola and barley, this contribution was not enough to compensate for the loss of income during the green manure production year. Therefore, growing faba bean as a green manure was not economical. Response of net revenue to N rates was mainly linear or quadratic, and N was optimal at 60 to 90 kg ha-1 at most sites. The results indicate that growing legumes for seed prior to canola can increase net revenues of canola and subsequent barley