The soilborne pathogen Plasmodiophora brassicae, causal agent of clubroot of canola (Brassica napus), is difficult to manage due to the longevity of its resting spores, ability to produce large amounts of inoculum, and the lack of effective fungicides. The cropping of clubroot resistant (CR) canola cultivars is one of the few effective strategies for clubroot management. This study evaluated the impact of the cultivation of CR canola on P. brassicae resting spore concentrations in commercial cropping systems in Alberta, Canada. Soil was sampled pre‐seeding and post‐harvest at multiple georeferenced locations within 17 P. brassicae‐infested fields over periods of up to 4 years in length. Resting spore concentrations were measured by quantitative PCR analysis, with a subset of samples also evaluated in greenhouse bioassays with a susceptible host. The cultivation of CR canola in soil with quantifiable levels of P. brassicae DNA resulted in increased inoculum loads. There was a notable lag in the release of inoculum after harvest, and quantifiable P. brassicae inoculum peaked in the year following cultivation of CR canola. Rotations that included a ≥2‐year break from P. brassicae hosts resulted in significant declines in soil resting spore concentrations. A strong positive relationship was found between the bioassays and qPCR‐based estimates of soil infestation. Results suggest that CR canola should not be used to reduce soil inoculum loads, and crop rotations in P. brassicae infested fields should include breaks of at least 2 years away from B. napus, otherwise the risk of selecting for virulent pathotypes may increase.

Additional index words. fruit breeding, fruit quality, postharvest handling, Rubus 'Caddo' (pronounced kad-oh) is the 14th release in a series of erect-growing, highquality, productive floricane-fruiting blackberry (Rubus L. subgenus Rubus Watson) cultivars intended for the fresh market developed by the University of Arkansas Division of Agriculture. Recent years have had increased focus on the improvement of flavor in blackberries in the Arkansas program, and 'Caddo' was developed with the intention of advancing flavor to a higher level in an additional thornless blackberry cultivar. 'Caddo' ripens mid-early season, near 'Osage' and slightly before 'Ouachita'

High tunnel (HT) winter production may be limited by extreme low air temperatures, suboptimal soil temperatures, large diurnal temperature changes, and short daylengths and associated low light conditions. To determine the productivity of spinach in extreme climates, HT production trials were conducted in the fall (October to December) and winter (January to March) of 2010–12 at the Greenville Research Farm in Logan, UT (lat. 41 N. elevation 1455 m). Soil heating (±) using electric cables and secondary covers (fabric rowcovers and plastic low tunnels) were evaluated to determine combined effects on fall and winter spinach production. Soil heating significantly increased yield in all cover treatments in the Fall 2010 (F2010) trial when spinach was planted in November, but had little to no effect on plant productivity in the other three trials (more appropriate planting dates) even though it did increase soil temperature marginally. The addition of secondary covers significantly increased plant biomass and leaf area when compared with the uncovered control. Excluding the F2011 trial when spinach was planted earlier under more favorable temperature and light conditions, the use of low tunnels resulted in significantly higher spinach yields (biomass and leaf area) than when grown under fabric rowcover. In the fall, relative growth rates (RGRs) decreased exponentially regardless of whether the soil was heated or not heated or if a secondary cover was used. This response was because of the seasonal decline in light levels and temperatures. In the winter production cycle, spinach relative growth without covers was similar or increased as climatic conditions improved. For plants grown under fabric or plastic rowcovers, RGR remained more constant or decreased during the production cycle. Increased yields were possible with secondary covers as air temperatures increase more quickly in the morning, maintained optimal temperatures longer each day (higher growing degree hours), and retained trapped heat later into the evening. Statistical interaction between heating cables and secondary covers were rarely observed. Fall and winter HT spinach production increases when further protection with secondary plant covers is provided; however, supplemental soil heating is not necessary.

Additional index words. Vitis, fruit quality, fruit breeding 'Compassion' seedless table grape is the newest cultivar (Vitis hybrid) released by the University of Arkansas Division of Agriculture, bringing to 13, the total number of releases from the program (Clark, 2010; Clark and Moore, 2013). It joins 'Hope', 'Faith', 'Joy', and 'Gratitude' in the recent inspiration series of table grapes from Arkansas. This cultivar expands options for table grape growers for local markets in the United States. This new development provides a substantial advancement in fruit crispness and firmness beyond that of previous Arkansas developments as well as an exquisite fruity flavor. It has green (white) skin and has shown limited fruit cracking or splitting in the climate of Arkansas. It has also shown consistent production and overall vine adaptation. In addition, 'Compassion' showed good performance and adaptation to the Willamette Valley, OR (Vance et al., 2017). 'Compassion' should be adapted in the midto upper-South and Pacific Northwest (PNW) of the United States but could be further evaluated for adaptation and hardiness in the lower Midwest, east of the Cascade Mountains in the PNW, or similar environments in the United States and the world. It is envisioned that 'Compassion' will be best used by local-market growers in areas where it is adapted. Origin 'Compassion' resulted from a cross of Ark. 2349 • Ark. 2304 made in 2002 (Fig. 1).