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Chrislyn A. Drake and James F. Hancock

Black root rot is a widespread disease of strawberry (Fragaria×ananassa Duchnesne) that causes the death of feeder roots and the degradation of structural roots. The major causal organisms of black root rot include Rhizoctonia fragariae Husain and W.E. McKeen, Pythiumspp. and Pratylenchuspenetrans(Cobb) Filipjev and Schuurmans Stekhoven. The current method of control for black root rot is methyl-bromide fumigation; however, methyl bromide is scheduled to be phased out in 2005, and its effects are short-lived in matted-row systems. The objectives of the study were to measure levels of tolerance to black root rot in 20 strawberry genotypes and to determine which pathogens were present in the soil. The genotypes were planted in four blocks each of methyl-bromide fumigated and nonfumigated soil, and were evaluated for crown number, number of flowers per crown, yield, and average berry weight over two years. The results showed that all three pathogens were present in the field, and that there was a significant genotype × fumigation interaction for yield and crown number in both years. The cultivars Bounty, Cabot, and Cavendish, all released from the breeding program in Nova Scotia, displayed tolerance to the pathogens that cause BRR. Greenhouse studies were conducted using a subset of the genotypes to determine if any one pathogen causes more damage than others, and to determine if susceptibility to a particular pathogen varies between genotypes.

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E.B. Poling

North Carolina is experiencing a revitalization of the strawberry industry due to the adoption of plasticulture technologies and the California cultivar Chandler, which produces excellent yields and fruit quality on black plastic mulch. With this system, berries can be harvested in just 7 to 8 months after planting. The spring harvest season can last up to 6 weeks in most years. Strawberry plasticulture growers in North Carolina typically experience yields of 17,000 to 18,000 lb/acre (19,054 to 20,174 kg·ha-1). Cash expenses for the system are about $4345/acre ($10,736/ha). The system requires both an overhead sprinkler system for blossom and bud frost/freeze protection, and drip irrigation for supplying water and fertilizer in the prebloom, bloom, and fruiting periods. Sandy loam and clay loam soils are ideal for forming the lo-inch-high (25.4-cm) beds with bedding machines. Usually, 33% of the N, 50% of the K, and all of the P is applied preplant, with the remaining N and K applied through the drip-irrigation system. Problems associated with the plasticulture system include higher initial investment relative to matted-row production, and only one fruiting season is possible with the anthracnose-susceptible `Chandler' in the southeastern United States.

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J.F. Hancock, S.C. Hokanson, P.W. Callow, M. Sakin, K. Haghighi and J.A. Flore

Twenty-one western and 13 eastern strawberry [Fragaria × ananassa (Duch.)] cultivars were grown in a polyethylene-covered greenhouse (polyhouse) in deep beds at either 10 × 10 or 25 × 25 cm spacing. Runners were removed weekly from the closest-spaced plants (hills), and the more open-spaced plants were allowed to set four runners on each side of the mother plant before the runners were removed (matted rows). Temperatures were allowed to fluctuate normally in the polyhouse, except that winter temperatures were maintained above 0C. The average yield of eastern and western cultivars did not differ significantly in most comparisons, but the average fruit weight of the Californian cultivars was significantly higher than the eastern ones, and Californian cultivars allocated a higher proportion of their biomass to reproduction. Nonbearing plants of eastern and western cultivars produced similar numbers of runners per plant and daughters per runner. There was no significant relationship between CO2 assimilation rate and yield. Interbreeding eastern cultivars with the most productive western genotypes might result in increased yields, but only if the higher reproductive efforts of the western types can be captured and transferred.

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Bernadine Strik, Timothy Righetti and Gil Buller

Fertilizer nitrogen (FN) recovery, and changes in nitrogen (N) and dry weight partitioning were studied over three fruiting seasons in June-bearing strawberry (Fragaria ×ananassa Duch. `Totem') grown in a matted row system. Fertilizer nitrogen treatments were initiated in 1999, the year after planting. The standard ammonium nitrate N application at renovation (55 kg·ha-1 of N) was compared to treatments where additional N was applied. Supplemental treatments included both ground-applied granular ammonium nitrate (28 kg·ha-1 of N) applied early in the season and foliar urea [5% (weight/volume); 16 kg·ha-1 of N] applied early in the season and after renovation. When labeled N was applied (eight of nine treatments) it was applied only once. The impact of no FN from the second through the third fruiting season was also evaluated. Fertilizer nitrogen treatment had no impact on total plant dry weight, total plant N, yield or fruit quality from the first through the third fruiting seasons. Net dry matter accumulation in the first fruiting season was 2 t·ha-1 not including the 4 t·ha-1 of dry matter removed when leaves were mowed during the renovation process. Seasonal plant dry weight and N accumulation decreased as the planting aged. Net nitrogen accumulation was estimated at 40 kg·ha-1 from spring growth to dormancy in the first fruiting season (including 30 kg·ha-1 in harvested fruit, but not including the 52 kg·ha-1 of N lost at renovation). Recovery of fertilizer N ranged from 42% to 63% for the broadcast granular applications and 15% to 52% for the foliar FN applications, depending on rate and timing. Fertilizer N from spring applications (granular or foliar) was predominantly partitioned to leaves and reproductive tissues. A large portion of the spring applied FN was lost when plants were mowed at renovation. Maximum fertilizer use efficiency was 42% for a granular 55 kg·ha-1 application at renovation, but declined to 42% just before plant growth the following spring, likely a result of FN loss in leaves that senesced. In June, ≈30% of the N in strawberry plants was derived from FN that was applied at renovation the previous season, depending on year. This stored FN was reallocated to reproductive tissues (22% to 35%) and leaves (43% to 53%), depending on year. Applying fertilizer after renovation increased the amount of remobilized N to new growth the following spring. The following June, 15% of plant nitrogen was derived from fertilizer applied at renovation 2 years prior.

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Douglas D. Archbold and Charles T. MacKown

Total N and fertilizer N (FN) recovery and use by June-bearing `Redchief' strawberry (Fragaria ×ananassa Duch.) and day-neutral `Tribute' grown in matted-row beds were studied over l-year periods. Fertilizer N was field-applied as NH NO at planting in June or September, and all plants were harvested from bed sections in late autumn (November) and at the completion of the spring harvest (June). Distribution patterns of vegetative biomass were similar in both cultivars, with leaf tissue comprising the bulk of the vegetative dry weight per plant at both sampling dates. The fall and spring fruit crops each contributed >40% of the total biomass per plant. Total N accumulation from soil N and FN increased as total biomass increased. Due in part to the additional biomass of the fall fruit crop, `Tribute' recovered 38% more total N per unit bed area than `Redchief'. Over 30% of the fall N total in `Tribute' and the spring N total in both cultivars was partitioned to the fruit. In both cultivars, greater recovery of FN applied in September that at planting time was observed by the postharvest sampling date. However, `Tribute' recovered only 14.2% of the FN applied in September, much less than the amount recovered by `Redchief' during the same interval, implying a diminished ability to absorb FN during fruiting. In all vegetative tissues, soluble reduced N (SRN) was consistently less than insoluble reduced N (IRN) in November and June. Consistent seasonal trends in SRN and IRN values were not evident in any tissue except roots, where SRN content declined from November to June. Allocation of FN to the SRN and IRN pools was related to FN application date, cropping pattern, and total biomass of the component tissue. In both cultivars, the FN content was greater in the IRN than the SRN pool and leaf IRN was the single largest vegetative sink for FN. Fruit N concentration was constant for most of the fall `Tribute' harvest period and declined in both cultivars during spring harvest. The spring `Tribute' fruit crop received more FN from the September than the planting application, while the fall crop exhibited the opposite pattern, suggesting the fruit crop receives more storage than newly absorbed FN. The accumulation of FN in the root SRN pool in November and its depletion through the spring harvest reveals that root SRN plays a significant role in the temporary seasonal storage and internal cycling of N remobilized during spring growth.

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Andrew R. Jamieson, Kevin R. Sanderson and Roger J.A. Tremblay

vigorous, resembling ‘Cavendish’ in habit, and they produce ample runners to establish matted rows. Plants are highly resistant to red stele root rot disease (incited by Phytophthora fragariae Hickman var. fragariae ) and moderately resistant to several

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Andrew R. Jamieson

’ are vigorous, and they produce ample runners to establish matted rows. Origin ‘AAC Lila’ is a seedling of a ‘Queen Elisa’ × ‘Wendy’ cross made in 2006 at Kentville, Nova Scotia, Canada, under the direction of A.R. Jamieson. ‘Queen Elisa’ [‘Miss

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Kim S. Lewers, Patricia R. Castro, John M. Enns, Stan C. Hokanson, Gene J. Galletta, David T. Handley, Andrew R. Jamieson, Michael J. Newell, Jayesh B. Samtani, Roy D. Flanagan, Barbara J. Smith, John C. Snyder, John G. Strang, Shawn R. Wright and Courtney A. Weber

, fruiting once a year from Maine through North Carolina. ʻFlavorfestʼ, with exceptional flavor and high yield, is recommended as an anthracnose-resistant cultivar for annual plastic-culture system and matted row production from Zones 4b–8a. Origin

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Chaim Kempler, Hugh A. Daubeny, Brian Harding, Lisa Frey, Tom E. Baumann, Chad E. Finn, Shahrokh Khanizadeh, Andrew R. Jamieson, Kenna MacKenzie, Patrick P. Moore and Mark Sweeney

Stolo means “people of the river.” Fig. 1. ‘Stolo’ strawberry ( A ) fruit and ( B ) matted row showing some tip-burn-like symptoms. Origin ‘Stolo’, tested as BC96-33-4, was bred by C. Kempler in 1995 and selected in Abbotsford, BC, by C. Kempler and H

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Andrew R. Jamieson, Kevin R. Sanderson, Jean-Pierre Privé and Roger J.A. Tremblay

early season, offering growers an alternative to ‘Annapolis’ with good fruit quality and yield. Plants of ‘Wendy’ are vigorous, resembling ‘Evangeline’ in habit, and they produce ample runners to establish matted rows. In greenhouse screening with