AAC Richmond is a white-hulled, spring oat (Avena sativa L.) cultivar developed at the Ottawa Research and Development Centre of Agriculture and Agri-Food Canada in Ottawa, ON. It was supported by the Ontario Cereal Crops Committee in January 2013 for registration and was registered on 20 Feb. 2014 (Canadian Food Inspection Agency no. 7488). AAC Richmond was later maturing and taller and showed higher grain and straw yield than check cultivars in eastern Canada. It was highly resistant to crown rust (Puccinia coronata Corda f. sp. avenae Eriks.).

AAC Bullet is a white-hulled, covered spring oat (Avena sativa L.) cultivar bred by the Ottawa Research and Development Center (ORDC), Agriculture and Agri-Food (AAFC). It was supported for registration by the Ontario Cereal Crops Committee (OCCC) in January 2011 and registered in Canada on 29 Oct. 2012 (CFIA registration no. 7251). In Ontario, AAC Bullet had significantly higher yield, better lodging resistance, and better resistance to crown rust but more days to heading than the control cultivars. From 2011 to 2015, AAC Bullet yielded 16% and 10% higher than trial means in southern and central Ontario, respectively, and has become one of the most popular oat cultivars in these regions.

AAC Almonte is a tan-hulled, covered spring oat (Avena sativa L.) cultivar bred by the Ottawa Research and Development Center of Agriculture and Agri-Food in Ottawa, ON. It was supported for registration by the Ontario Cereal Crops Committee in January 2013 and registered in Canada on 20 Feb. 2014 (registration no. 7487). AAC Almonte is adapted to and has performed well in southern Ontario since its release due in part to its outstanding crown rust (Puccinia coronata Corda f. sp. avenae Eriks.) resistance.

Fusarium head blight (FHB) is a destructive disease of oats in Canada. To assist the development of FHB-resistant cultivars, the influence of timing of inoculation and pathogenicity of four Fusarium spp. causing FHB were examined on 12 oat genotypes under controlled environmental conditions. Early inoculations with F. graminearum at or before the complete emergence of ears resulted in little or no visible FHB symptoms but deoxynivalenol (DON) contents ranging from 0.9 to 3.7 ppm were detected in the harvested grain. Severe levels of FHB were observed on these genotypes with infected spikelets (IS) ranging from 40 to 75% and DON concentrations, from 6.3 to 10.2 ppm, when plants were inoculated at or after the 50 % anthesis stage. Inoculation at the 50 % anthesis was considered the most appropriate timing as it allowed sufficient time for disease development and assessment prior to physiological maturity of the plant. Of the four Fusarium spp., F. culmorum and F. graminearum were equally highly pathogenic, having areas under the disease progress curve (AUDPC) of 45.3 and 47.3, and DON content in the harvested grain of 10.4 and 14.3 ppm, respectively. Fusarium sporotrichioides resulted in the lowest AUDPC (31.2) and was significantly less pathogenic than the two highly pathogenic species. Fusarium avenaceum was intermediate and the resulting AUDPC (36.7) was not significantly different from those of either the highly pathogenic or the weakly pathogenic species. The oat genotype and Fusarium spp. interaction was not significant, suggesting that breeding for resistance to F. graminearum may also confer enhanced resistance to other Fusarium spp. Introduction Oat (Avena sativa L.) is a common crop grown for both feed and food in Canada. In 2012, Canada produced over 2.6 million tonnes of oats, making it the third largest producer of oats next to the European Union and Russia (Statistics Canada 2013). Oats contain high amounts of valuable nutrients such as dietary fiber, ß-glucans, proteins, unsaturated fatty acids antioxidants, proteins, dietary fiber, vitamins, and minerals (Behall et al. 1997; Sobotka et al. 2012; Tsopmo et al. 2010; Wood 1990). Due to their beneficial effects on human health, the use of oats and oat products for human food has been increasing in recent years (North American Millers’ Association and the National Oat Improvement Committee 2008; Peterson 1992). During the past 20 years, there has been an increase in the incidence of Fusarium head blight (FHB) on oats grown in the Canadian Prairies (McCallum et al. 1999; Tekauz et al. 2004, 2008, 2011) and in the eastern provinces of Ontario and Québec (Couture and Lévesque 1995; Couture et al. 1996; Tamburic-Ilincic 2010; Xue and Chen 2010, 2014) where the majority of oats is grown in Canada. As a result, seed harvested from these regions may contain a considerable portion of Fusarium-infected kernels resulting from infection by several Fusarium spp. (Clear et al. 1996, 2000; Tamburic-Ilincic 2010; Tekauz et al. 2008, 2011). A number of research reports have demonstrated that FHB lowers grain yield and quality; the fungi also produce deoxynivalenol (DON), zearalenone and HT-2 mycotoxins in the kernels, which are harmful to livestock and pose a safety concern in human food (Bottalico and Perrone 2002; Clear et al. 2000; Parikka et al. 2008; Placinta et al. 1999; Tamburic-Ilincic 2010). Consequently, there has been an increase in disease awareness and the development of management strategies to mitigate the adverse effects of FHB on oats (Gavrilova et al. 2008; Mitchell Fetch et al. 2008; Tekauz et al. 2008; Yan et al. 2008, 2010). Several Fusarium species including F. acuminatum Ellis and Everhart, F. avenaceum (Corda: Fr.) Sacc., F. culmorum (W.G. Smith) Sacc., F. equiseti (Corda) Sacc., F. graminearum Schwabe (teleomorph Gibberella zeae (Schwein.) Petch.), F. poae (Peck) Wollenw., and F. sporotrichioides Sherb. have been frequently isolated from Fusarium-infected kernels (Clear et al. 1996; Tamburic-Ilincic 2010; Tekauz et al. 2008, 2011; Xue and Chen 2010, 2014). Among these species, F. graminearum is the principal causal agent of FHB in Canada (Clear et al. 1996, 2000; Tekauz et al. 2008, 2011). Studies on the pathogenicity of these Fusarium species to wheat and barley revealed that only F. graminearum and F. culmorum were highly pathogenic, and the other species were intermediate or weakly pathogenic (Stack et al. 1997; Wong et al. 1995; Xue et al. 2004, 2006). There has been no study on the comparative pathogenicity of Fusarium species causing head blight of oats. Although FHB severity can be reduced or controlled by foliar fungicide applications, the use of genetic resistance is considered one of the most practical and environmentally safe measures for disease management (Mitchell Fetch et al. 2008; Tekauz et al. 2004, 2008; Yan et al. 2008, 2010). High levels of resistance to FHB have been identified in oat germplasm and considerable breeding has been conducted to develop resistant cultivars and lines (Gavrilova et al. 2008; Mitchell Fetch et al. 2008; Tekauz et al. 2008; Yan et al. 2010). The reactions of oat lines to FHB have commonly been evaluated by field screening, which depends on the natural occurrence of Fusarium spp. or artificial inoculation in a FHB nursery (Mitchell Fetch et al. 2008; Yan et al. 2010). These methods do not account for the effect of the timing of inoculation on oat reactions to FHB, differences in pathogenicity of Fusarium spp., and any possible Fusarium species by oat genotype interactions. As a result, breeders have frequently encountered inconsistent disease reactions in their breeding lines, leading to significant loss of time and resources (Yan et al. 2010). The objectives of this research were to determine the effect of timing of inoculation on oat variety reactions to FHB and to compare the pathogenicity of four commonly observed Fusarium spp. in causing FHB under controlled environmental conditions. Materials and methods Plant materials and growth conditions Twelve oat cultivars and lines originated from diverse sources and having shown different levels of resistance to FHB based on field evaluations (A. McElroy, personal communication) were used (Table 1). Seeds were planted in 15-cm diameter pots containing a mixture of loam soil, sand and composted cow manure (1:1:1, v/v/v), and were maintained at 23-25 °C during the day and at 18-20 °C during the night in a greenhouse. Supplemental light was provided by 300-W metal halide lamps to ensure a 16-h photoperiod and a minimum intensity of 360 mol m s. Plants were thinned to three plants per pot. Five weeks after planting, the plants were supplied with a 1 % solution of 20-20-20 (N-P-K) fertilizer. Due to genotypic differences in maturity, seeds were planted serially over a two-week period, so that all genotypes were at the same growth stage when they were inoculated. Pathogen species and inoculum production To determine the inoculation timing effect on the FHB reactions of the 12 oat genotypes, three isolates of F. graminearum, DAOM 178148, DAOM 212678, and DAOM 232369, were used. Four Fusarium spp. including F. avenaceum, F. culmorum, F. graminearum, and F. sporotrichioides were used to examine the species effect on the varietal reactions to FHB in the 12 oat genotypes. These Fusarium spp. are either reported to cause FHB on oat or frequently isolated from Fusarium-infected kernels in Canada (Clear et al. 1996, 2000; Tamburic-Ilincic 2010; Tekauz et al. 2008, 2011; Xue and Chen 2010, 2014). One isolate from each of the four Fusarium spp. was used: DAOM 232349, DAOM 232360, DAOM 232372, and DAOM 232384, representing F. avenaceum, F. culmorum, F. graminearum, and F. sporotrichioides, respectively. The Fusarium isolates used in the present study were obtained from the Canadian Collection of Fungal Cultures at Agriculture and Agri-Food Canada’s Eastern Cereal and Oilseed Research Centre (ECORC-AAFC), Ottawa, Canada. DAOM stands for Department of Agriculture, Ottawa, Mycology and is an internationally recognized acronym for the national mycological herbarium of Canada. Table 1. Origins of 12 oat genotypes used for studies on the influence of timing of inoculation and Fusarium spp. on the development of Fusarium head blight and deoxynivalenol contamination in harvested grains.

Dry matter production from temperate pasture species is typically very low during midsummer. Switchgrass (Panicum virgatum L.) is being investigated as an alternative pasture species to overcome this problem. We studied two populations over 3 yr to determine if they had sufficient cold tolerance to be used in these areas. Populations selected from cv. Pathfinder were grown in plots at Ottawa and sampled from September to late November in 1985–1987. Each fall, samples were dug at intervals of 2 or 4 wk, the tops and roots trimmed back, then placed in plastic bags in a programmed freezer to determine the temperature at which 50% of the plants were killed (LT50). Percent crown moisture was also measured in the falls of 1985 and 1986. Prior to the onset of cold hardening in September, the two switchgrass populations had LT50 values of −4 °C. Slow cold-hardening occurred to the end of September, followed by a very rapid increase in cold tolerance to −18 °C at the end of October. During November, the rate of hardening decreased and cold tolerance came to a plateau of −19 to −22 °C by the end of the month. The same range has been reported for winter hardy cultivars of timothy and alfalfa. Crown moisture decreased to a plateau several weeks before LT50 values indicating that moisture is of questionable use as an indicator of cold tolerance in switchgrass. Good cold tolerance in switchgrass combined with superior survival during the severe winter of 1982/1983 and vigorous regrowth from overwintering rhizomes lead us to believe that winter hardy cultivars for central and eastern Ontario could be selected from this material.Key words: Switchgrass, Panicum virgatum L., low temperature tolerance, winter survival, forage plant