About

Cindy Tong is a Professor in the Department of Horticultural Science at the University of Minnesota Twin Cities. She holds a Ph.D. in Plant Physiology from the University of California - Davis. Her research focuses on how the preharvest growing environment of fruits and vegetables affects their postharvest attributes, such as sugar content and flavor. She is particularly interested in understanding the genetics of the 'Honeycrisp' apple and its progeny, specifically how these genetics contribute to the fruit's ability to stay crisp during cold storage and the environmental factors that lead to storage disorders. Dr. Tong investigates the interaction between environment and genetics in affecting fruit and vegetable quality, with an emphasis on postharvest disorders. Her work aims to identify genetic bases for traits like apple crispness retention and to understand how environmental conditions influence the development of storage disorders. She also explores ways to manipulate environmental factors to improve crop resilience under changing environmental conditions. In outreach activities, she collaborates with extension educators and other stakeholders to develop methods and tools for farmers to manage harvest and storage challenges, including variety trials and educational programs for Minnesota fruit and vegetable growers.

Research topics

• Biology
• Horticulture
• Mathematics
• Genetics
• Chemistry
• Geography
• Botany

Selected publications

• Swede Midge (Contarinia nasturtii Keiffer) Phenology and Management in Minnesota Community Gardens

  HortScience · 2025-01-31 · 1 citations

  articleOpen access1st authorCorresponding

  Swede midge is a major insect pest of brassicas, including broccoli ( Brassica oleracea L. var. italica) , cauliflower ( B. oleracea L. var. botrytis ), collards ( B. oleracea L. var. viridis ), and kale ( B. oleracea var. sabellica ). The insect infests and feeds on the growing tips of plants, resulting in distorted leaves or lack of heading of broccoli and cauliflower. Since 2014, when continuous trapping began in Minnesota, USA, it has primarily been found in community gardens in the Twin Cities metropolitan area. Trapping data obtained at Saint Paul community gardens over 3 years indicated that swede midge phenology in any particular garden varied from year to year. Gardeners surveyed in 2023 indicated some knowledge of swede midge, were unsure of how to recognize infestation symptoms, and were interested in collaborating to test management methods. A simple mitigation system using bamboo poles, polypropylene fabric, and weed barrier was tested for its ability to reduce infestations by blocking access to plants by adults and to soil by larvae and prevent emergence by previously pupating generations. It was 50% to 80% effective compared with unprotected controls.

  PublisherDOI

• Light, temperature, and floral preservative effects on postharvest longevity of perennial flax ( <i>Linum</i> spp.) cut flowers

  The Journal of Horticultural Science and Biotechnology · 2025-06-23

  articleSenior author
  PublisherDOI

• Postharvest Quality of ‘Keepsake’ Apple Fruit

  HortTechnology · 2024-08-01

  articleOpen access1st authorCorresponding

  Storage information regarding ‘Keepsake’ apple fruit is lacking. The objective of this research was to investigate the postharvest characteristics of ‘Keepsake’ apple ( Malus × domestica Borkh.), which is a parent of ‘Honeycrisp’. Apples were obtained from three orchards in Minnesota in 2022 and 2023, assessed for quality, and stored at 0 to 1 °C or 4 to 5 °C in air. Fruit were tested for firmness, soluble solids content (SSC), and titratable acidity (TA) for up to 6 months in storage. At harvest, fruit from different orchards differed in ground color, firmness, SSC, and titratable acidity. The starch pattern index did not differ among the orchards within a year, but it was greater during the 2023 harvest than during the 2022 harvest. Fruit firmness decreased less rapidly at 0 to 1 °C than at 4 to 5 °C. Changes in SSC with storage varied by orchard, storage temperature, and year. In 2022 to 2023, SSC changes were highly variable, remained the same during storage for fruit from one orchard, increased and then decreased for fruit from another orchard, increased after 1 month of storage, and then remained unchanged thereafter for fruit from the third orchard. In 2023 to 2024, SSC was generally unchanged during storage at 0 to 1 °C, and it increased slightly over time during storage at 4 to 5 °C. Titratable acidity decreased during storage, but there was no difference between storage temperatures. These findings demonstrate the difficulty determining when to harvest ‘Keepsake’ fruit because neither starch pattern index nor ground color is a reliable indicator of ripeness. Growers must rely on experience and fruit redness to determine when to harvest this late-season cultivar. To prolong fruit firmness, growers should store ‘Keepsake’ fruit at 0 to 1 °C rather than at 4 to 5 °C.

  PublisherOA PDFDOI

• Detection of Spotted-winged Drosophila (Diptera: Drosophilidae) Infestations in Blueberry Fruits1

  Journal of Entomological Science · 2023-06-26 · 1 citations

  articleOpen access1st authorCorresponding

  Spotted-winged drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), has become a significant pest of small and stone fruit. Unlike most Drosophila species, it tends to infest healthy, intact ripe fruit, as opposed to rotting or overripe fruit (Mitsui et al. 2006, Popul. Ecol. 48:233–237; Asplen et al. 2015, J. Pest Sci. 88:469–494). Spotted-winged drosophila adults are typically detected in the field using baited traps. This is useful in helping growers decide when to apply insecticides (Ebbenga et al. 2022, J. Entomol. Sci. 57: 516–529), but methods are also needed to estimate actual fruit infestation levels. Spectral imaging of fruit may provide a nondestructive alternative to extraction of larvae and could provide information on the infestation status of a single fruit. Such imaging has been tested for insect pests other than D. suzukii. For example, Peshlov et al. (2009, J. Near Infrared Spectrosc. 17:203–212) used near-infrared spectroscopy (NIRS) to detect infestation of wild blueberries (Vaccinium) by blueberry maggot, Rhagoletis mendax Curran (Diptera: Tephritidae). By measuring spectra of a live larva and subtracting it from an infested blueberry, they demonstrated that the NIR signal they recorded was from a larva and “associated chemical changes in the blueberries.” Detectable differences between infested blueberry and larvae occurred between approximately 750 and 1300 nm, with a small differential signal at 600 nm. Tsuta et al. (2006, Food Sci. Technol. Res. 12:96–100) also used spectroscopy to discriminate between blueberry fruit and “foreign substances.” They measured the spectra of various foreign substances, including worms, separately from the fruit. They detected a difference in the second derivative of absorbance between worms and berries between approximately 625 and 675 nm.The F-750 Produce Quality Meter (Felix Instruments, Camas, WA) is a handheld visible and near-infrared spectrometer that has been used to predict ripeness of various fruit correlated with fruit constituents, such as dry matter content of cherry, Prunus avium L. (Toivonen et al. 2017, Can. J. Plant Sci. 97:1030–1035). Light transmitted from the device's xenon tungsten lamp interacts with the scanned object and then is transmitted near the zone of illumination where the signal is recorded. The portability of this device allows its use in agricultural fields and may be useful beyond postharvest fruit quality determination. Infestation levels of D. suzukii eggs and first instars are undetectable by the human eye. If the F-750 meter is capable of distinguishing infested from uninfested fruit, the device would allow sorting or culling by small-acreage farmers who may not have storage facilities cold enough to arrest D. suzukii development (Aly et al. 2017, J. Econ. Entom. 110:87–93). This work was conducted to determine to what extent infestation can be detected using the F-750 spectrometer in blueberries and raspberries (Rubus).To test the possibility that the F-750 spectrometer could be used to detect D. suzukii, in-field infestation assays and artificial infestation assays with store-bought blueberry fruit in the laboratory were initiated. For field infestation samples, ‘Northblue’ and ‘Chippewa’ blueberries (V. corymbosumL.ｘV. angustifoliumAit.) were harvested from the Sand Plain Research Farm of the University of Minnesota in Becker, MN (45°23′36.42′’N, 93°52′36.3′’W). Berries were collected weekly between 5 and 26 July 2017 (100 in week 1 and then 50 each in weeks 2, 3, and 4), scanned with the F-750 spectrometer in the laboratory, and then placed in 30-mL containers (Dart Container Corp., Mason, MI), with one fruit per container. The containers were incubated at room temperature (21–23°C), and fly emergence was recorded 1 wk later.Artificial infestation assays were initiated with store-bought blueberry fruit in the laboratory. Blueberries were purchased from a grocery store, and berries with disease, previous insect infestation, or turgor loss were discarded prior to artificial infestation. Scans of fruit that were infested were compared with that of uninfested fruit and fruit that were uninfested but poked using an insect pin (BioQuip Insect Pins, Black, #0, Bioquip Products, Rancho Dominguez, CA) to simulate ovipositor injury without the presence of eggs or larvae. To infest fruit, individual berries were incubated with two mated D. suzukii females for 24 h in 30-mL clear plastic containers with a square of filter paper to absorb excess liquid. Adult flies were removed after 24 h, after which all containers were placed in a growth chamber at 23–25°C, with a 16-h light:8-h dark photoperiod. Individual fruits were scanned 4 or 7 d after infestation. Control treatments included (1) fruit not poked and not infested and (2) poked but not infested.One-way blind tests were conducted in 2021. Intact fruit were rinsed three times with deionized water, air dried, dipped in 2% (v/v) propionic acid (Fisher Scientific, Hampton, NH) for 5 s to inhibit mold growth, air dried, and then poked with an insect pin to provide ovipositor entry sites. Individual fruits were placed in 30-mL containers and randomly assigned to an infested or uninfested category using R statistical software. Five female and five male (to insure mating) flies, approximately 3 d old, were added to each “infested” treatment container. No flies were added to containers serving as untreated controls. All containers were placed in a growth chamber kept at 23–25°C, with a 16-h light: 8-h dark photoperiod. After 36 h, flies were removed, and berries were viewed under a stereo microscope to check for the presence of egg breathing filaments. Containers of berries were then delivered to the scanner who did not know which containers contained infested fruit. Fruits were scanned 48, 72, and 120 h after initial infestation and scored for larval emergence 7 d after introduction to D. suzukii adults.Each berry was scanned once with the F-750 Produce Quality Meter. Blueberries were scanned with pedicel-ends down on the light-emitting surface. A ring was fabricated from Delrin acetal homopolymer (DuPont, Wilmington, DE, USA) to fit on top of the 11-mm reflector cone to improve the support of berries over the central ring of the small fruit adapter provided by the manufacturer. Only the machine-computed second derivatives of absorbance data were collected. The routine used by the F-750 meter can be explained as a nine-point second order Savitzky-Golay filter (Savitzky and Golay 1964, Anal. Chem. 36:1627–1639).The accuracy rates of one-way blind predictive tests were conducted according to Hodgson et al. (2004, J. Econ. Entomol. 97:2127–2136). The probability of making a correct determination of infestation across all data sets = Rpi (true positivesi+true negativesi), where pi is the proportion of n data sets represented by set i; true positivesi is the probability of correctly identifying infestation; and true negativesi is the probability of correctly identifying no infestation. Because there were seven data sets of similar size (50–99 berries), pi = 0.143.Field-harvested ‘Chippewa’ and ‘Northblue’ (Fig. 1A) berries showed similar patterns of spectral changes with harvest week. Mean second derivatives of absorbance in the 660- to 690-nm range increased, but decreased in the 692- to 715-nm range over time. None of the berries from harvests 1 and 2 were infested with D. suzukii. Twenty percent of harvest 3 and 96% of harvest 4 ‘Chippewa’ berries and 42% of harvest 3 and 100% of the harvest 4 ‘Northblue’ fruit were infested. Thus, mean second derivatives of absorbance of infested fruit were greater than that of uninfested fruit in the 660- to 690-nm range and less in the 692- to 715-nm range. Similarly, mean second derivatives of absorbance in the 660- to 690-nm range of artificially infested berries were greater, whereas those in the 692- to 712-nm range were less than those of berries that were uninfested or poked (Fig. 1B). Although scans of the field-grown and laboratory-infested berries suggested that spectral patterns could be used to discriminate between uninfested and infested fruit, accuracy of one-way blind assays varied from 53% to 71%, whereas error rates varied from 29% to 47% (data not shown), and the proportion of correct true positives was 0.13, whereas that of true negatives was 0.48 (Table 1). The method was better able to predict negatives (specificity) than positives (precision or recall).The inability of the device used in this study to accurately predict positive infestations may be due to its decrease in signal-to noise ratio at about 980 nm. However, data obtained at wavelengths greater than 1000 nm may improve discrimination of infested and uninfested blueberries. Also, improved statistical analysis using partial least squares modeling and the use of machine learning algorithms could improve the predictive ability of spectrometers to detect D. suzuki infestation in berries.We thank Naxo Riera Vila and Lucy DeBoer for technical assistance, James Luby for blueberries, and Geoffrey Harms for designing and fabricating a small fruit adapter for the F-750 spectrometer. Funding was provided by a University of Minnesota College of Food, Agriculture, and Natural Resources Faculty Development Grant and the Minnesota Experiment Station for Project MN21-043.

  PublisherOA PDFDOI

• ‘Honeycrisp’ Apple Maturity, Quality and StorageDisorders According to Interior and Exterior Tree CanopyPosition

  Journal of American Pomological Society · 2022-10-01

  articleOpen accessSenior author

  Apples are typically spot picked according to color and, therefore, indirectly according to canopy light exposure that affects fruit peel anthocyanins. We studied how interior and exterior canopy positions influenced fruit maturity and storage disorder incidence in ‘Honeycrisp’ apples grown in Maine (ME) USA, Minnesota (MN) USA and Ontario (ON) Canada, and harvested two to three times. Harvest maturity was more advanced in exterior compared with interior fruit. In both ME and ON, index of absorbance difference (IAD) was higher for interior fruit compared to exterior fruit. Starch pattern index (SPI) was lower in interior fruit in ME and ON during the first harvest, but not the later harvests, and not in MN where starch breakdown was advanced. Internal ethylene concentration (IEC) at harvest, measured in ON only, was lower in interior fruit during the first harvest, but no difference occurred between the two positions in the latter two harvests. After four months of cold storage plus 1- and 7-d shelf tests, IEC (measured in ON only) was lower in exterior fruit. In all three sites, soft scald, soggy breakdown and bitter pit incidence did not vary between the canopy positions. Fruit were not conditioned to 10 degrees C and stored at 0.5 °C to allow for full development of chilling injury disorders. Canopy position altered fruit maturation and quality with no significant effect on soft scald or bitter pit.

  PublisherOA PDFDOI

• Postharvest Characteristics of ‘MN80’ (Triumph™)Apple Fruit Compared to ‘Cortland’ and ‘Honeycrisp’

  Journal of American Pomological Society · 2022-10-01

  articleOpen access1st authorCorresponding

  ‘MN80’, a cross between ‘Honeycrisp’ and ‘Liberty’, a newly-released apple sold under the Triumph trademark, is meant to be marketed primarily to home gardeners and small-scale commercial orchards. It was selected for release based on its fruits’ resistance to apple scab, thus requiring less spraying than scab-susceptible cultivars. The quality of ‘MN80’ fruit from two growing locations over multiple years was assessed at harvest and after storage for four months at 0-1 °C and 4-5 °C. Mean firmness of Wisconsin-grown ‘MN80’fruit decreased as harvest week increased, but mean fruit fresh weight and total soluble solids concentration (SSC) remained the same over harvest time, which was also observed for ME-grown fruit. Fruit stored at 4-5 °C exhibited more shrivel and loss of firmness than fruit stored at 0-1 °C. Percentages of fruit showing internal browning and soft scald in storage increased with harvest date for ME-grown fruit in 2019 but not 2021. Consumer sensory panels evaluating newly-harvested fruit liked ‘Honeycrisp’ and Maine-grown ‘MN80’fruit best, followed by Wisconsin-grown ‘MN80’fruit, then ‘Cortland’ fruit. However, after 4 months of storage, Maine-grown ‘MN80’ fruit had the highest overall liking scores of all the stored cultivars. Mean sensory attribute scores of Maine- and Wisconsin-grown ‘MN80’ fruit changed little with storage, whereas stored ‘Honeycrisp’ and ‘Cortland’ had lower scores than newly-harvested fruit. For all cultivars, storage temperature had no effect on sensory attribute scores. These data suggest that ‘MN80’ fruit retain characteristics that appeal to consumers between harvest and 4-5 months of cold storage.

  PublisherOA PDFDOI

• Alleviation of Postharvest Skin Dimpling of MN55 Apple Fruit and a Possible Association with Apple stem pitting virus

  HortScience · 2021-06-08

  articleOpen access1st authorCorresponding

  MN55 is an apple ( Malus × domestica Borkh.) cultivar recently released by the University of Minnesota apple breeding program, with fruit marketed in the U.S. as Rave ® . When stored for 4 months at 0 to 4 °C, MN55 fruit can develop several storage disorders, including skin dimpling. Skin dimpling incidence was greater for fruit harvested 1 week later than those harvested earlier. Dimpling was not alleviated by prestorage treatments of 1-methylcyclopropene or diphenylamine or by holding fruit at room temperature for 1 day before long-term cold storage. However, dimpling incidence was very low when fruit were stored at 6 to 7 °C. Because viruses have been implicated in other fruit dimpling disorders, the presence of viruses in MN55 leaves and fruit was studied. Apple stem pitting virus (ASPV) was detected by microscopy, reverse transcriptase polymerase chain reaction (RT-PCR) methodology, and high throughput sequencing (HTS) in peel of fruit from MN55 trees that exhibited skin dimpling after 4 months of storage at 0 to 1 °C. ASPV was also detected in supermarket-purchased fruit of other cultivars with noticeable skin dimpling. Although ASPV was not conclusively demonstrated to cause skin dimpling in our work, its prevalence indicates that further investigations are warranted to determine the relationship between viruses and skin deformities in stored apples.

  PublisherOA PDFDOI

• Artificial Shading Can Adversely Affect Heat-tolerant Lettuce Growth and Taste, with Concomitant Changes in Gene Expression

  Journal of the American Society for Horticultural Science · 2021-12-09 · 3 citations

  articleOpen accessCorresponding

  Shading has been used to produce high-quality lettuce ( Lactuca sativa ) in locations where production conditions are not optimal for this cool-season crop. To learn what additional benefits shading provides if heat-tolerant cultivars are used and to understand the effects of shading on growth, sensory quality, chemical content, and transcriptome profile on heat-tolerant lettuce, we grew two romaine lettuce cultivars with and without shading using 50% black shadecloth in 2018 and 2019. Shading reduced plant leaf temperatures, lettuce head fresh weights, glucose and total sugars content, and sweetness, but not bitterness, whereas it increased lettuce chlorophyll b content compared with unshaded controls. Transcriptome analyses identified genes predominantly involved in chlorophyll biosynthesis, photosynthesis, and carbohydrate metabolism as upregulated in unshaded controls compared with shaded treatments. For the tested cultivars, which were bred to withstand high growing temperatures, it may be preferable to grow them under unshaded conditions to avoid increased infrastructure costs and obtain lettuce deemed sweeter than if shaded.

  PublisherOA PDFDOI

• Growing Asparagus in Minnesota

  2020 · 1 citations

  • Horticulture
  • Geography
  • Biology

  This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu.

  Publisher

• Regional Variation in the Index of Absorbance Difference as an Indicator of Maturity and Predictor of Storage Disorders in Apples

  HortScience · 2020 · 10 citations

  Senior authorCorresponding
  • Horticulture
  • Biology
  • Botany

  We evaluated regional variation in the Delta Absorbance Meter® index of absorbance difference (I AD ) as a measure of harvest maturity and for predicting the occurrence of storage disorders in ‘McIntosh’ apples [ Malus ×sylvestris (L.) var . domestica (Borkh.) Mansf.] in 2016 and ‘Honeycrisp’ apples in 2016 and 2017. Apples were grown in Maine (ME), Minnesota (MN), and Ontario (ON), and they were harvested from one orchard in each region, and two to three times each year, followed by cold storage at 0.5 °C for 2 months in 2016 and 4 months in 2017. In 2016, ‘Honeycrisp’ I AD values were similar in ME and ON, but lower than in MN. In 2017, I AD was greater in ME than in the other two regions during the first harvest, and it similar to MN in the latter two harvests and lower in ON than in the other regions. In ‘Honeycrisp’ apples, I AD was more strongly related to starch pattern index (SPI), internal ethylene concentration, and fruit peel blush than to chlorophyll or soluble solids concentration. Soft scald incidence (SSI) of ‘Honeycrisp’ fruit was greater in ME than in MN and ON in both years. In ME, SSI was related to I AD at harvest in both years, but with an inverse relationship with the first harvest and a positive relationship in the second harvest. A positive relationship also occurred in ON in 2017. SSI was not related to I AD at harvest in MN in both years and ON in 2016. Regional similarities in patterns of change in ‘Honeycrisp’ fruit I AD were not consistent from year to year, and this indicates that a single I AD standard should not be used to assess fruit maturity in different regions. In ‘McIntosh’, I AD values were variable among the three regions and were not related to other maturity indicators. I AD was not useful for measuring maturity in ‘McIntosh’ apples, but it was weakly related to core browning incidence.

  PublisherOA PDFDOI

Frequent coauthors

• Renae E. Moran

  University of Maine

  43 shared

• Jennifer R. DeEll

  Ministry of Agriculture, Food and Rural Affairs

  42 shared

• Nicholas P. Howard

  26 shared

• Changbin Chen

  Arizona State University

  25 shared

• Yizhou Ma

  The University of Texas Health Science Center at Houston

  25 shared

• Gail J. Celio

  Imaging Center

  25 shared

• Yin Xu

  Beijing Institute of Genomics

  25 shared

• Hsueh‐Yuan Chang

  University of Minnesota

  18 shared

Labs

• Cindy Tong's LabPI

  Not provided

Awards & honors

• CFANS Distinguished Diversity and Inclusion Award (Faculty),…
• Thank a Teacher, 2007
• Community-University Connections partnership, 2002