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Harvesting labor is the largest annual variable operating expense for apple (Malus ×domestica) orchard enterprises and is subject to escalating costs and shortages. In Europe, much of the cider apple harvesting is done with machinery, greatly reducing production costs. However, despite a rapid increase in hard cider production in North America over the past 15 years, mechanical cider apple harvesting has not been widely implemented. In this study, we compared mechanical with hand harvesting costs for model 5-, 15-, and 60-acre cider apple orchards located in New York using a partial budget model. Scale-appropriate harvesters were identified for use at each farm scale. Sensitivity analyses were used to test the cost differential for using each piece of machinery on varying orchard sizes and to model changes in labor costs. Across all orchard scales, we found that mechanically harvesting cider apples was more profitable than hand harvesting, with larger operations breaking even sooner and realizing greater returns than operations using hand harvesting. Mechanical harvesting costs broke even with hand harvesting in years 16, 7, and 5 and by year 30 reduced cumulative harvesting costs by 23%, 52%, and 53% in our 5-, 15-, and 60-acre model orchards, respectively. Increasing the orchard size resulted in greater returns from mechanical harvesting. Using the machinery in the 15-acre orchard scenario on a 30-acre farm resulted in costs breaking even with hand harvesting in year 3; by year 30, the cumulative costs resulted in 66% lower harvesting costs than hand labor. Mechanical harvesting remained profitable when labor wages were decreased and became more profitable in scenarios with increasing wages. For example, in the 60-acre orchard, mechanical harvesting cost 41% less than hand harvesting with a 2% annual compounding decrease in labor wages; with 2% annual compounding increase in labor wages, the mechanical harvesting cost was 63% less than hand harvesting. In addition to the cost savings, mechanical harvesting allows for harvesting cider apples with fewer logistical challenges, such as contracting, housing, and transporting migrant labor. [ABSTRACT FROM AUTHOR]

This study was designed to determine the efficacy of canker excision (CE) followed by a subsequent application of cauterization (CAU) and/or fungicide treatment to the excised area for the management of anthracnose canker (caused by Neofabraea malicorticis) on cider apple (Malus ×domestica) trees. Three experiments were conducted from 2015 to 2017, with one experiment each year, in an experimental cider apple orchard in western Washington where trees were naturally infested with N. malicorticis. Treatments were applied once in December and data were collected January through March. Treatments in the 2015 experiment were CE D CAU, CE D CAU D copper hydroxide, CE D 0.5% sodium hypochlorite, Bordeaux mixture (BM) only, and CE D copper hydroxide (control). The 2016 experiment included the same treatments as in 2015 plus one additional treatment, CE D BM. In 2017, one additional treatment was added, CE only, and CAU treatments were removed as they caused significant injury to the trees. Canker size was measured pretreatment, and the treated canker or excised area was measured posttreatment every 2 weeks for 13-15 weeks. Compared with pretreatment, cankers treated with BM did not increase in size, while the excised area treated with CAU increased 28-fold in size on average, and the excised area treated with 0.5% sodium hypochlorite or copper hydroxide increased up to 4-fold in size. Each year new cankers developed in all treatments 13-15 weeks after treatment application, at a time of year when there should not be any spores present to cause new infections. Dark brown streaking, indicative of the disease, was observed in the tissue below the intact or excised cankers 15 months after treatment application all years. Although N. malicorticis was not isolated from symptomatic tissue, symptoms were observed in all treatments including where cankers had not been excised and there was no wounding of the cambium tissue. Findings from this study indicate that of the treatments evaluated, the application of copper hydroxide after CE was the most effective for limiting the number of new cankers, but it did not limit expansion of the excised area. Additional physical and fungicidal strategies need to be tested for effective management of anthracnose canker. [ABSTRACT FROM AUTHOR]

Complex changes in gene expression occur during postharvest storage of apple (Malus ×domestica) and often precede or accompany changes in ripening and disorder development. Targeted gene expression analysis fundamentally relies on previous knowledge of the targeted gene. Minimally, a substantial fragment of the gene sequence must be known with high accuracy so that primers and probes, which bind to their targets in a complimentary fashion, are highly specific. Here, we describe a workflow that leverages publicly available transcriptome data to discover apple cultivar-specific gene sequences to guide primer design for quantitative real-time polymerase chain reaction (qPCR). We find that problematic polymorphisms occur frequently in 'Granny Smith' and 'Honeycrisp' apple when candidate primer binding sites were selected using the 'Golden Delicious' genome. We attempted to validate qPCR-based gene expression measurements with RNA sequencing (RNA-Seq) analysis of the same RNA samples. However, we found that agreement between the two technologies was highly variable and positively correlated with the similarity between cultivar-specific genes and RNA-Seq reference genes. Thus, we offer insight that 1) improves the accuracy and efficiency of qPCR primer design in cultivars that lack sufficient sequence resources and 2) better guides the essential step of validation of RNA-Seq data with a subset of genes of interest examined via qPCR. [ABSTRACT FROM AUTHOR]

To identify genotypes of apple (Malus ×domestica) rootstock with vulnerability to low temperature, we measured the low temperature tolerance of xylem, phloem and cambium in 2-year-old shoot pieces from cultivars Budagovsky 9 (B.9), M.7 EMLA (M.7), M.9 EMLA (M.9), Geneva® 41 (G.41), Geneva 30 (G.30), Geneva 214 (G.214), Geneva 814 (G.814), and Geneva 935 (G.935), as well as six advanced selections in the Geneva (G.) series and three in the Vineland (V.) series. From Oct. 2013 to Apr. 2014, injury was measured as a 0-10 rating based on percentage of discolored cross-sectional xylem and phloem, and cambial length and circumference with brown discoloration, with 0 indicating no browning and 10 indicating browning in the entire tissue. From Oct. 2014 to Apr. 2015, injury was measured as xylem, phloem and cambium browning using a similar rating scale that accounted for both the percentage of browned tissues and the intensity of browning. Following exposure to -35 to -40 °C, many genotypes, including 'M.7', 'M.9', 'G.935', G.4011, G.4292, G.5087, and V.5, had only partial xylem injury in the fall, whereas others, 'M.7', 'G.41', 'G.214', and G.4011, had more extensive xylem browning at -30 °C and colder. 'G.30' had moderate to severe xylem browning at -15 to -19 °C. In late October of both years, G.4013 exhibited severe phloem browning at relatively high temperatures, but accrued additional hardiness by Nov. 2014, whereas genotypes 'B.9', 'M.9', 'G.30', and 'G.41' developed considerable phloem hardiness by late October with no additional increase in hardiness in November. Geneva and Vineland genotypes exhibited a low degree of susceptibility to injury at -35 to -40 °C in Jan. 2014 and Mar. 2015. Shoot hardiness in Apr. 2014 and 2015 was highly variable between the 2 years, with severe browning of xylem and cambium at -40 °C in every genotype sampled in Apr. 2014, but not in Apr. 2015. 'M.9' and G.3902 appeared to be the least vulnerable to injury in April, whereas 'G.30', 'G.41', 'G.814', G.4292, and G.5257 seem more likely to suffer injury in spring. 'G.30' had tender xylem in both fall and spring, G.4013 had the least hardy cambium and phloem in fall, and G.5257 the least hardy cambium in the spring. These genotypes are vulnerable to damaging temperatures during fall acclimation and spring deacclimation. [ABSTRACT FROM AUTHOR]

Cultivar and planting site are two factors that often receive minimal attention, but can have a significant impact on the quality of apple (Malus ×domestica) produced. A regional project, NE-183 The Multidisciplinary Evaluation of New Apple Cultivars, was initiated in 1995 to systematically evaluate 20 newer apple cultivars on Mailing.9 (M.9) rootstock across 19 sites in North America. This paper describes the effect of cultivar and site on fruit quality and sensory attributes at a number of the planting sites for the 1998 through 2000 growing seasons. Fruit quality attributes measured included fruit weight, length : diameter ratio, soluble solids concentration (SSC), titratable acidity (TA), flesh firmness, red overcolor, and russet. Fruit sensory characteristics rated included crispness, sweetness, and juiciness, based on a unipolar intensity scale (where 1 = least and 5 = most), and acidity, flavor, attractiveness, and desirability based on a bipolar hedonic scale (where 1 = dislike and 5 = like extremely). All fruit quality and sensory variables measured were affected by cultivar. The two-way interaction of cultivar and planting site was significant for all response variables except SSC, TA, russet, crispness, and sweetness ratings. The SSC:TA ratio was strongly correlated with sweetness and acidity sensory rating, but was weakly correlated with flavor rating. The results demonstrate that no one cultivar is ideally suited for all planting sites and no planting site is ideal for maximizing the quality of all apple cultivars. [ABSTRACT FROM AUTHOR]

Half or whole root systems of micropropagated ‘Gala’ apple (Malus x domestica Borkh.) plants were subjected to drought stress by regulating the osmotic potential of the nutrient solution using polyethylene glycol (20% w/v) to investigate the effect of root drying on NO3-content and metabolism in roots and leaves and on leaf photosynthesis. No significant difference in predawn leaf water potential was found between half root stress (HRS) and control (CK), while predawn leaf water potential from both was significantly higher than for the whole root stress (WRS) treatment. However, diurnal leaf water potential of HRS was lower than CK and higher than WRS during most of the daytime. Neither HRS nor WRS influenced foliar NO3-concentration, but both significantly reduced NO3-concentration in drought-stressed roots as early as 4 hours after stress treatment started. This reduced NO3-concentration was maintained in HRS and WRS roots to the end of the experiment. However, there were no significant differences in NO3-concentration, between CK roots and unstressed roots of HRS. Similar to the effect on root NO3-concentration, both HRS and WRS reduced nitrate reductase activity in drought-stressed roots. Moreover, leaf net photosynthesis, stomatal conductance and transpiration rate of HRS plants were reduced significantly throughout the experiment when compared with CK plants, but the values were higher than those of WRS plants in the first 7 days of stress treatment though not at later times. Net photosynthesis, stomatal conductance and transpiration rate were correlated to root NO3-concentration. This correlation may simply reflect the fact that water stress affected both NO3-concentration in roots and leaf gas exchange in the same direction. [ABSTRACT FROM AUTHOR]