Bacterial spot, caused by Xanthomonas arbicola pv. pruni, is considered an economically important disease of peach and other stone fruit. In peaches, bacterial spot can affect leaves, twigs, and fruit. The disease can cause slight to nearly complete defoliation of infected trees. When significant defoliation occurs early in the season, fruit size can be reduced. In more severe cases, fruit may become infected. Small water-soaked spots can develop on the fruit at any time during fruit development. Early infection is the most concerning because unsightly cratering or pitting on the fruit can occur. Copper based fungicides are the main product used to manage bacterial spot in peaches and are associated with the potential for elevated phytotoxicity. This damage to the leaves resembles the actual disease and can cause defoliation in severe cases. Bacteriophage technology employs viruses that specifically infect bacteria offering a targeted approach to managing bacterial spot without the risk of phytotoxicity. The efficacy of these products have not been widely tested in the southeastern United States. The objective of this study was to determine the optimal timing during the growing season for applying a bacteriophage product in Central Alabama to achieve control of bacterial spot that is comparable to or better than a traditional copper-based spray program. A study was conducted at the Chilton Research and Extension Center in Clanton, AL. Treatments were applied to single tree replications and each treatment was replicated four times. The study followed a randomized complete block design. The control treatment (standard protocol) consisted of a copper-based product applied at each phenological stage. Bacteriophage treatments consisted of applications of the bacteriophage at select phenological stages in place of the copper-based product. Treatments were applied weekly. The entire canopy of each treatment tree was rated for incidence of bacterial spot every two weeks. At harvest, fruit were separated by degree of bacterial spot infection, counted, and weighed. Applications of bacteriophage during specific phenological stages—such as from pink to open bloom, delayed dormant to early bud swell, and from petal fall to early shuck split—were associated with the lowest incidence of foliar bacterial spot. Across all bacteriophage treatments, most fruit exhibited only mild symptoms and remained marketable. These findings suggest that targeted application timing may improve bacteriophage efficacy, though additional studies are needed to validate and optimize these strategies.
Sweet cider serves as both a fresh juice product and a precursor for hard cider production and is an important facet of agrotourism within the apple industry in the U.S. In this study, juice characteristics and physiological traits of apple cultivars developed by the Midwest Apple Improvement Association (MAIA) and apple cultivars bred at Iowa State University (ISU) by Spencer Ambrose Beach were compared to an industry-standard cultivar for sweet cider quality from 2022 to 2024. Given the historical and economic significance of apple production in Iowa during the early 1900s and its subsequent decline due to multiple factors, including a devastating winter storm that killed thousands of apple trees, this research examines the potential for regionally bred cultivars to compete with established industry standards. Juice quality parameters were analyzed, including pH, Brix, titratable acidity (TA), sorbitol content, nutritional composition, and oxidation rates. Flowering and harvest dates were assessed to determine the impact of climatic risks like spring and fall freezes, which are typical weather occurrences and concerns for apple growers in the Midwest during bloom and harvest periods, respectively, on production timing and feasibility. Preliminary findings indicate that Secor (ISU) demonstrated comparable juice quality metrics to the industry standard GoldRush and ranked highest in sensory preference evaluations. Sweet Zinger (MAIA) also received high consumer preference scores, suggesting promise as a regionally bred apple that is marketable both as a fresh-eating or cider apple. One cultivar, the Original Delicious (Iowa), scored the lowest consistently in consumer preference. While having relatively high Brix, it lacked acidity, with a pH of 4.0. GoldRush, a preferred cultivar, had a pH value of 3.2, suggesting the need for blending with more acidic cultivars to optimize cider quality. These findings provide insight into the quality and economic viability of regionally bred cultivars and their potential role in strengthening the cider industry in the U.S. Midwest.
Traditional cider apples are typically classified by their sugar, acid, and phenolic composition and concentration, which all impact the sensory profile and fermentation characteristics of the final beverage. Despite the practical importance of these traits, the genetic basis underlying cider apple fruit quality remains poorly understood and few functional genetic markers have been successfully adapted for cider apple breeding. Using a genome-wide association study (GWAS) on 253 cider apple accessions from the USDA-Plant Genetic Resources Unit Malus collection held in Geneva, NY, we found 19 significant marker-trait associations for titratable acidity, pH, total polyphenols, and non-structural carbohydrates. Notably, we identified a distinct marker on chromosome 15 strongly associated with total polyphenols, a key determinant of bitterness and astringency. A major association on chromosome 16, near the Ma1 locus, explained a substantial proportion of the phenotypic variance for titratable acidity and pH, confirming the importance of this region. Significant marker-trait associations were detected for sugar concentration on chromosomes 1, 6, 8, and 10. Further analysis confirmed identification of favorable alleles for titratable acidity, total polyphenols, glucose and sucrose concentration. These results provide a foundation for identifying apple cultivars with desirable phenotypic traits for cider production from germplasm collections and for making marker assisted selections within breeding programs.
The Foraged Fruit Project began in 2021 and involves researchers from Cornell and Rutgers Universities, with support from the New York Cider Association and funding from the David M. Einhorn Center for Community Engagement. The aim of this project was to better understand the practice of foraging in New York through a transdisciplinary lens, which includes ethnographic interviews, genetic identification of apple trees, and fruit quality assessments of the foraged apples. Over 30 commercial cider producers were interviewed for this study and we analyzed fruit samples from nearly 50 different trees. Seventy-eight percent of the submitted samples were unique apple genotypes, meaning there was no match among the thousands of samples in the MyFruitTree reference panel managed by Washington State University. According to the Long Ashton Research Station’s cider apple classification, 45% of the apple samples were bittersharp, 14% were bittersweet, 35% were sharp, and 6% were sweet. Based on these data, New York cider producers are largely foraging for high tannin and high acid apples which are difficult to procure from commercial apple producers in the region. Common themes revealed through the ethnographic interviews related to climate change resiliency, reparation for indigenous groups, intellectual property control, discovering unique genetics, and access to public and private lands. By studying these factors, we sought to better support the practice of foraging, unlock unique apple genetics that can benefit growers in a rapidly changing climate, and increase the profitability and uniqueness of New York cider.
Modern apple production has moved from traditional open orchard formats to that of high-density trellised plantings. As industry has shifted, the number of trees in commercial apple orchards typically reaches 1,500 per acre, making the management of these orchard blocks on a per-tree basis impractical. The use of unmanned aerial vehicles (UAVs) in the form of portable drones offers a method for collecting image data for thousands of trees in a matter of minutes. Combining these UAVs with multispectral cameras, which collect visual data on spectra that the human eye cannot perceive, allows for the calculation of vegetation indices (VIs) such as the normalized difference vegetation index (NDVI) for individual trees. Many VIs correlate with important orchard management considerations such as tree vigor, nutrient status, and disease severity. Multiple challenges hinder the incorporation of VIs into orchard management: parsing data on a per-tree basis is challenging in high-density systems, there is no comprehensive understanding of how VIs vary across a growing season and between cultivars, and at what magnitude deviation from expected norms is indicative of a weak tree is uncertain. This experiment aimed to classify this variation in VIs by examining a large cohort of cultivars at multiple timepoints and sites. A DJI Mavic 3M equipped with a 4-channel (green, red, red edge, and near infrared) multispectral camera was used to perform flights at both commercial and research orchards in upstate New York. Orthomosaics of each site were created using Agisoft Metashape and analyzed in QGIS and R (using the FIELDimageR package). Results showed statistically significant differences in VI values between cultivars and timepoints. These differences increased in intensity later in the growing season- in September, differences in cultivar explained 40% of the observed variance in NDVI at one orchard site, compared to only 19% in July.
Understanding the dynamics of oxidative stress during the growth of strawberry fruits is essential for optimizing fruit yield, quality, and shelf life. By strategically targeting reactive oxygen species (ROS) generation and the antioxidant defense mechanisms across various developmental stages, researchers and producers can refine cultivation practices, resulting in healthier and more flavorful strawberries. Strawberry fruits were categorized into six distinct developmental and ripening stages: small-size green fruits (S1, indicating the early stage of development), medium-size green fruits (S2, characterized by continued growth and elongation), full-size green fruits (S3, where the fruit attains its final size), white fruits (S4), turning-stage pink fruits (S5), and fully matured red fruits (S6). To evaluate the influence of oxidative stress and antioxidant defenses throughout the growth phases, several parameters were analyzed. These included hydrogen peroxide (H2O2), malondialdehyde (MDA), superoxide dismutase (SOD), lipoxygenase (LOX), catalase (CAT), guaiacol peroxidase (GPOD), ascorbate peroxidase (APOD), glutathione reductase (GR), and glutathione-S-transferase (GST). The levels of H2O2 and MDA exhibited variation across the different developmental stages. SOD and POD activities demonstrated an initial increase followed by a decline, while CAT and APOD levels showed a decrease in the later stages of fruit development. Additionally, LOX activity was elevated in the early developmental stages and declined as maturation progressed. The intricate role of oxidative stress in strawberry fruit growth highlights its significance for improving cultivation methods and post-harvest management. This understanding not only contributes to delivering superior-quality strawberries to consumers but also promotes sustainable agricultural practices.
Many low-lying coastal areas worldwide, including Florida, experience soil salinization due to tropical rainstorms, storm surges that cause superficial flooding with saline water, and groundwater salinization from saltwater intrusion. Additionally, excessive fertilizer applications can increase soil salinization, which can reduce the productivity of soil and affect crop growth. This study evaluated the response to salinity stress of two peach rootstocks: 1) Flordaguard, the current recommended rootstock in Florida, and 2) MP-29, a peach-plum hybrid rootstock with the potential to be recommended in the state. A total of 60 plants were distributed in five blocks and exposed to three salinity levels (0, 75, and 150 µM NaCl) for 24 days in a greenhouse. Photosynthetic rate (A), stomatal conductance (gs), and efficiency of photosystem II (ΦPSII) were recorded every other day. Stem water potential (Ψs) and foliar nutrient concentrations were assessed at the end of the experiment. A decline in A level was observed in all plants over time, with a higher reduction under salinity treatments. Starting 16 days after treatment, gs was significantly lower in plantlets exposed to 150 µM NaCl compared to controls. Interestingly, ΦPSII was more stable in Flordaguard plants during the experiment. Moreover, ΦPSII response suggested higher sensitivity to salinity in MP-29 plants. Similarly, Ψs in salinity stressed plants was at least 33% lower compared to the control group. On the other hand, Ψs in ‘MP-29’ was 11% lower compared to ‘Flordaguard’, indicating higher water stress in the hybrid rootstock. Foliar nutrient concentrations were influenced by treatment (N), cultivar (Ca, B, Mn, Zn), or their interaction (Mg, S), while P, K, Fe, and Cu remained unchanged. These results suggest that MP-29 rootstock is more sensitive to salinity stress than Flordaguard, which may have implications for rootstock selection in saline-prone soils.
Table olives in California have historically been hand-harvested. Hand labor crews are increasingly difficult to attract to small acreage orchards and are often prohibitively expensive when available. Mechanical harvesting equipment is available; however, harvest efficiencies typically range from 55-65%, leaving 35-45% of the crop on the tree. While much less expensive than hand-harvesting, the harvest efficiency is not adequate and leaves growers to decide whether to glean the remaining crop or forfeit the income from that portion of the crop. This low efficiency is partially due to the inherent architecture and physiology of olive trees. Additionally, the force required to remove an olive fruit from the tree is relatively high because table olives are harvested before their physiological maturity. In 2024 we conducted a study to evaluate the effects of altering tree architecture by skirting trees in May, removing lower limbs up to 4 feet from the ground to avoid any contact with the harvest machinery. This led to a 15.5% increase in harvest efficiency over trees where lower limbs were left, without affecting total yield. In addition, we examined the effect of a foliar application of 1-aminocyclopropane-1-carboxylic acid (ACC, commercially available as Accede®), an ethylene precursor, at 100 gallons per acre of 1500ppm solution a week before harvest. ACC applications reduced the amount of force required to remove fruit from the tree by 26% and increased harvest efficiency by up to 10.7%. The combination of both removing the skirts of the trees and applying ACC improved harvest efficiency by 23%. These strategies provide clear pathways to improving the economic sustainability of the table olive industry in California.
