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Timothy W. Miller, Carl R. Libbey and Brian G. Maupin

Propane flaming and organic amendments were evaluated for usefulness in matted-row strawberry (Fragaria ×ananassa Duch.). Flaming was used once before transplanting ‘Hood’ strawberry (PRETR), twice before transplanting (PRETR + PRETR), or once before and once after transplanting (PRETR + POSTR) and compared with rototilling before transplanting in 2000–02. Organic amendments tested across flame treatments included corn gluten meal (CGM) at two rates, wheat gluten (WG), and mustard seed meal (MSM) with high or low glucosinolate content, and herbicides included oxyfluorfen, pendimethalin, and a combination of oxyfluorfen + pendimethalin. Amendments/herbicides were applied immediately POSTR in Year 1 and again to established plants in late winter of Year 2. All plots were weeded by hand after weed evaluations were completed and weeding hours recorded. The trial was conducted twice: Iteration 1 and Iteration 2. Effect of flaming on grass and broadleaf weed ratings was brief during Year 1 of both iterations, with only slight differences observed in June and no differences by September. Total weeding time was reduced 12% by flaming PRETR once compared with rototilling in Iteration 1 and was reduced 10% by all flame treatments in Iteration 2. Rototilling reduced total berry yield and average individual fruit weight compared with flaming treatments in Iteration 1; there was no significant effect of flame on strawberry yield or individual fruit weight in Iteration 2. Organic amendments did not reduce weeding time in Iteration 1 compared with the nontreated control, although weeding time was increased 18% by CGM at 487 kg·ha−1 compared with synthetic herbicide treatments. In Iteration 2, total weeding time was reduced 14% for the two pendimethalin treatments and for high-glucosinolate MSM compared with nontreated control plots. First-year strawberry leaf area was reduced by oxyfluorfen + pendimethalin compared with nontreated strawberries (802 and 1086 cm2/plant, respectively) and was generally increased with organic amendments. Strawberry yield in Iteration 1 was increased ≈14% by CGM at 974 kg·ha−1 and WG and low-glucosinolate MSM compared with nontreated strawberry. Oxyfluorfen and oxyfluorfen + pendimethalin reduced strawberry yield by ≈20% and average individual fruit weight by ≈9% (14.8 and 14.5 g/fruit) compared with nontreated strawberry (16.1 g/fruit); high-glucosinolate MSM also reduced average individual fruit weight to 14.8 g/fruit. There were no significant effects of amendments/herbicides on strawberry yield parameters in Iteration 2.

Open access

Maria Gannett, Marvin P. Pritts and Johannes Lehmann

Soil amendments with varying carbon:nitrogen (C:N) ratios [grass clippings, wheat (Triticum aestivum), straw, sawdust] were pre-plant incorporated into 12 × 15-ft field plots at ≈4 tons/acre in fall and then planted to perennial strawberry (Fragaria ×ananassa) the following spring and grown 4 years. These amendments were intended to alter soil biological activity as measured by a suite of soil tests referred to as “soil health indicators” which, in turn, were hypothesized to affect strawberry plant growth and yield. In addition, plots were either tilled deeply or shallowly to determine if intensity of tillage affected soil health indicators. After the first and second years, amendments were reapplied between rows and soil and plant variables continued to be monitored. Soil respiration was consistently higher in plots with higher C:N amendments, with up to a 189% increase in respiration in sawdust-amended plots over unamended plots. The respiration rate was highest in sawdust-amended shallow-tilled plots; however, in most cases, tillage depth had no effect on other soil or plant variables. Potentially mineralizable N was higher in sawdust-amended plots in May both years, but not throughout the rest of the season. Soil moisture and pH were 21% and 2% higher, respectively, between the rows of strawberries than within the rows by September of the planting year, and remained that way throughout the next year. Neither the C:N ratio of the soil nor the foliar nutrient concentration of strawberry leaves was affected by the C:N ratio of the amendments. Most significantly, plant density and yield were depressed up to 42% and 26%, respectively, by planting into straw-amended soil, but planting into other amendments did not have this effect. After the second fruiting year (the third growing season), only straw was incorporated into half of the plots after harvest to mimic winter straw mulch incorporation, and yield was measured again the following spring. However, incorporation of straw between rows after plants were established did not affect yield. This study corroborates the general recommendation to avoid new strawberry plantings in locations that were recently planted to strawberry, as old fields likely harbor pathogens and contain undecomposed straw residue from previous years’ mulching that could depress yield. Despite differences in soil health indicators between amendment and tillage treatments, yield differences were not correlated with them. These observations suggest that alternative soil health indicators may be better suited for perennial strawberry.

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Todd L. Mervosh and James A. LaMondia

The effects of terbacil herbicide on strawberry (Fragaria ×ananassa Duch. `Honeoye') yield and black root rot disease were determined in field plots at two locations in Connecticut over 4 years. Terbacil treatments at up to four times the maximum label dosage caused some temporary foliar chlorosis but did not affect the health of structural or perennial roots and associated feeder roots. Development of secondary root growth (perennial roots) was not influenced by terbacil. Terbacil had no effect on the quantity of lesion nematodes [Pratylenchus penetrans (Cobb) Filip & Schur. Stek.] extracted or the amount of the fungal pathogen Rhizoctonia fragariae Husain and McKeen isolated from strawberry roots. At both locations, R. fragariae was common on plant roots by the fourth year. Terbacil treatments did not affect strawberry yields in terms of number or weight of ripe berries per plot. Our results indicate that terbacil does not contribute to black root rot or decreased yields in `Honeoye' strawberry. Chemical name used: 5-chloro-3-(1,1-dimethylethyl)-6-methyl-2,4-(1H,3H)-pyrimidinedione (terbacil).

Free access

Thomas R. Gordon, Douglas V. Shaw and Kirk D. Larson

Previous studies have demonstrated significant genetic variation for susceptibility to verticillium wilt, caused by Verticillium dahliae, among strawberry (Fragaria ×ananassa Duch.) genotypes adapted to California growing conditions. These evaluations have been conducted using a conidial root-dip inoculation procedure; valid application of this method in a breeding program assumes the reaction of inoculated plants will be predictive of their response to infection by more natural means. To test this expectation, we evaluated the responses of plants representing eight strawberry genotypes that were either root-dip inoculated prior to being transplanted into a fruit production field or were transplanted into soil artificially infested with pathogen propagules (microsclerotia). Both inoculation methods revealed significant variation among genotypes in all 3 years that tests were conducted and the absence of significant genotype × treatment interactions demonstrate similar rankings of genotypes with both methods. However, based on statistical repeatability, the root-dip inoculation method was more consistent over time (R = 0.759) than the soil inoculation method (R = 0.510).

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Jianzhi Jenny Zhang and Christopher B. Watkins

The effects of postharvest treatments of air and 20 kPa CO2 (in air) at 2 or 20 °C on color, firmness, accumulations of acetaldehyde, ethanol, and ethyl acetate, activities of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activity, and expression of an ADH gene were studied in strawberry fruit (Fragaria ×ananassa Duch. cv. Jewel). CO2 treatment enhanced strawberry fruit firmness at 2 °C but not 20 °C, while the rate of color changes was affected by CO2 treatment at 20 °C but not at 2 °C. Temperature also affected the accumulation of acetaldehyde, ethanol and ethyl acetate in CO2-treated fruit. All three compounds accumulated in fruits at 2 °C. At 20 °C, ethanol accumulated slightly by day 6, although ethyl acetate accumulated in fruit from both atmospheres. PDC enzyme activity was higher in CO2-treated fruit than their air-treated control at 2 °C but not at 20 °C. ADH activity and ADH mRNA accumulation of the CO2-treated berries were higher than in air at 20 °C but not 2 °C. The results, overall, indicate that patterns of change among gene expression, enzyme activities, and fermentation product accumulation were not consistent.

Free access

Tomas N. Hasing, Luis F. Osorio and Vance M. Whitaker

Previous studies have recognized considerable variation in the soluble solids content (SSC) of strawberries (Fragaria ×ananassa) during Florida’s fruiting season. Cultivars with stable fruit SSC over time would be valued in the commercial industry as a result of their more uniform quality. The within-season stability of 410 genotypes from the strawberry breeding program of the University of Florida was estimated using data from clonally replicated first-year seedlings and advanced selections evaluated at two locations over two consecutive seasons. Stability was measured using a linear regression approach. For each genotype, the SSC measured at different harvest dates was regressed on the mean SSC of an independent set of genotypes at each harvest date. Genotypes with steep slopes are sensitive to small environmental and physiological changes and are considered unstable compared with genotypes with slopes close to zero. Approximately 90% of individual genotype slopes were not different from the population slope value and were classified in the average stability group, whereas the remaining 10% were equally distributed between the unstable and stable groups. Although a preliminary genetic analysis indicated that SSC stability may have low narrow-sense heritability (h 2 = 0.06 ± 0.05), a group of genotypes exhibited stability across multiple environments. Soluble solids content stability and mean soluble solids were independent, and genotypes with both stable and high levels of SSC were observed.

Free access

J. Pablo Fernández-Trujillo, Jacqueline F. Nock and Christopher B. Watkins

Effects of 20 kPa CO2 treatments on concentrations of fermentation products, organic acids, and activities of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH), were measured in fruit of selected strawberry cultivars (Fragaria ×ananassa Duch. `Annapolis', `Cavendish', `Honeoye', `Kent', `Jewell', `Lateglow', and `NorthEast'). Acetaldehyde, ethanol, and ethyl acetate concentrations accumulated in CO2-treated fruit of `Honeoye' and `Kent', but not in `Cavendish' or `Annapolis'. The former two cultivars were classified as intolerant to high CO2 and the latter two as tolerant to high CO2. Activities of PDC and ADH were higher in CO2-treated than in air-treated fruit of the tolerant cultivars but not in the intolerant cultivars. Succinate accumulated in fruit of all cultivars, but concentrations were higher in the tolerant than in the intolerant cultivars. Results are discussed in relation to tolerance of fruit to CO2.

Free access

Katherine B. Wing, Marvin P. Pritts and Wayne F. Wilcox

Blackening and decay of roots in association with plant stunting are common in perennial strawberry (Fragaria ×ananassa Duch.) plantings worldwide; this syndrome is commonly referred to as black root rot (BRR), although its causal agent(s) are not well characterized. We conducted a New York field survey that measured many physical and cultural factors in healthy and diseased fields to identify those most strongly associated with BRR. Factors significantly correlated with BRR symptoms were soil compaction, fine soil texture, absence of raised beds, high application rates of the herbicide terbacil, advanced age of planting, nonuse of the fungicide metalaxyl, and cumulative years of strawberry monoculture. Populations of Pratylenchus spp. were not associated with poor root health. The data suggest that most factors that compromise root growth may predispose strawberry plants to infection by site-specific BRR pathogens. Chemical names used: 3-tert-butyl-5-chloro-6-methyluracil (terbacil); N-(2,6-dimethylphenyl)-N-(methoxyacetyl) alanine methyl ester (metalaxyl).

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James F. Hancock, Patrick P. Edger, Peter W. Callow, Thomas Herlache and Chad E. Finn

Fragaria × ananassa ? Acta Hort. 348 85 93 Hancock, J.F. Finn, C.A. Hokanson, S.C. Luby, J.J. Goulart, B.L. Demchak, K. Callow, P.W. Hummer, K.E. 2001b A multistate comparison of native octoploid strawberries from North and South America J. Amer. Soc. Hort

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Craig K. Chandler, Bielinski M. Santos, Natalia A. Peres, Celine Jouquand and Anne Plotto

There are two predominant strawberry ( Fragaria × ananassa Duch.) production systems throughout the world: open-field cultivation and production under protective structures (e.g., high tunnels and greenhouses). In California and Florida