`Honeycrisp' is a new apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] cultivar that has been planted extensively in North America, but the storage disorders soggy breakdown and soft scald have resulted in major fruit losses. The effects of harvest date and storage temperature on fruit quality and susceptibility of fruit to these disorders have been investigated in Michigan, New York, and Maine. Internal ethylene concentrations were variable over a wide range of harvest dates, and a rapid increase in autocatalytic ethylene production was not always apparent. The starch pattern index, soluble solids content, titratable acidity and firmness also appear to have limited use as harvest indices. Development of soggy breakdown and soft scald is associated with later harvest dates and storage of fruit at temperatures of 0 to 0.5 °C compared with higher storage temperatures. It is recommended that `Honeycrisp' be stored at 3 °C, although storage disorders still can occur at this temperature if fruit are harvested late. In addition, greasiness development may be worse at higher storage temperatures.
Christopher B. Watkins, Mustafa Erkan, Jacqueline F. Nock, Kevin A. Iungerman, Randolph M. Beaudry, and Renae E. Moran
Jianjun Chen, R.W. Henley, R.J. Henny, C.A. Robinson, and R.D. Caldwell
Aglaonema is among the most popular tropical ornamental foliage plants used indoors because of its bright foliar variegation, low light and humidity tolerance, and few pests. Aglaonema, however, has been labeled as one of the most chilling-sensitive foliage plants. The dark, greasy-appearing patches on leaves injured by chilling can result in completely unsalable plants. With recent breeding activity, more and more Aglaonema cultivars have been developed and released. How new cultivars respond to chilling temperatures is, however, mostly unclear. This study was undertaken to evaluate cultivar chilling responses to identify chilling-resistant cultivars. Twenty cultivars were chilled at 1.7, 4.4, 7.2, 10, and 12.7 °C for 24 h using a detached single-leaf method and also whole-plant assay. Results indicate that great genetic variation exists among the cultivars, ranging from no injury at 1.7 °C to severe injury at 12.7 °C. A popular cultivar, Silver Queen, is the most sensitive, while the cultivar Stars is the most resistant. There was also a chilling response difference based on leaf maturity. Young leaves showed less injury than did either mature or old leaves. In addition, there was a significant correlation between the single-leaf and whole-plant assay for chilling resistance in Aglaonema'; the single leaf assay could be particularly useful for a quick test.
Zhiguo Ju, Yousheng Duan, and Zhiqiang Ju
Effects of different plant oils (soybean oil, corn oil, olive oil, peanut oil, linseed oil, and cotton seed oil) and oil component emulsions on scald development in `Delicious' apples were studied. Prestorage treatment with commercial plant oils reduced scald development, but was not as effective as 2000 mg•L-1 diphenylamine (DPA) after 6 months of cold storage. Different oil components played different roles in affecting scald. At 6% or 9% concentrations, neutral lipids (mono-, di-, and tri-acylglycerols), and phospholipids inhibited scald to the same level of 2000 mg•L-1 DPA treatment. Free fatty acids partially reduced scald, while α-tocopherol at 3% or higher concentrations accelerated scald development. There were no differences in scald inhibition between unsaturated neutral lipids and saturated neutral lipids or among the different acylated neutral lipids. When α-tocopherol was stripped from plant oils, the stripped plant oils at 6% or 9% controlled scald to the same level of 2000 mg•L-1 DPA treatment. Emulsions of 6% or 9% neutral lipids, phospholipids, or stripped plant oils did not induce greasiness on fruit skin. Fruit treated with lipids, phospholipids, or stripped plant oils looked greener and fresher compared with the control by the end of storage.
James J. Ferguson, Fedro S. Zazueta, and Juan I. Valiente
Fungal diseases have their greatest impact on citrus in Florida by reducing tree vigor, fruit yield, and quality. Given the complex etiology of these diseases, this software was developed to facilitate diagnosis of symptoms and to explain the dynamics of Alternaria brown spot of mandarins, greasy spot, melanose, Phytophthora brown rot, post-bloom fruit drop, and sour orange scab. CITPATH includes a diagnostic key to identify symptoms of the major fungal diseases of citrus foliage and fruit in Florida and a hypertext program containing a description and graphic display of symptoms, maps of geographic occurrence, diagrams of disease development, and management strategies. Users can also consult a list of citrus cultivars susceptible to specific diseases and a reciprocal list of diseases affecting specific cultivars. Chemical control methods are discussed briefly with reference to the current Florida Citrus Spray Guide, a hardcopy of which is included with the software purchase. Developed for commercial growers, county extension programs, citrus horticulture classes, and master gardeners, this software is available on CD-ROM disks containing other citrus databases and as a separate disk for MS-DOS-based computers.
Christopher B. Watkins, William J. Bramlage, and Belinda A. Cregoe
To examine the hypothesis that superficial scald of apple (Malus domestics Borkh.) is a chilling injury, `Granny Smith' apples were stored at temperatures ranging from 0 to 20C, temperature-conditioned before storage, and warmed during storage. Fruit stored at 0 or 4C developed supeficial scald. At 10C, surface defects occurred but they were not typical symptoms of scald, and at 15 or 20C no symptoms developed. Accumulation of α-1 faroesene and conjugated trienes in fruit peel correlated with increasing ethylene production, which was greater at higher temperatures. However, concentrations of conjugated trienes were highest at 0 and 4C. When fruit were kept at 10C for 5 or 10 days before storage, scald development after storage was not reduced. An interruption of 0C storage with a single warming period at 10 or 20C reduced scald development after 25 weeks of storage, maximum reduction occurring when fruit were warmed for 3 to 5 days at 20C after 1 to 4 weeks at 0C. Amelioration of scald declined as time at 0C before warming increased. Diphenylamine application after the same intervals at 0C, instead of warming, also was less beneficial as time before treatment increased. α-Farnesene and conjugated trienes increased during warming, but at the end of storage (when scald was developing) the conjugated triene concentrations in peel were reduced in fruit that had been warmed. Warming slightly increased yellowing, softening, and greasiness of fruit after storage, We conclude that chilling induced superficial scald on `Granny Smith' apples.
Kathleen Delate, Andrea McKern, Robert Turnbull, James T.S. Walker, Richard Volz, Allan White, Vincent Bus, Dave Rogers, Lyn Cole, Natalie How, Sarah Guernsey, and Jason Johnston
fitted with a miniature infrared CO 2 transducer, using O 2 -free N as the carrier gas (40 mL·min −1 ). Greasiness of apple peel was determined by a tactile measurement and rating system ( Brookfield, 1999 ) of 0 point (no greasy peel), 1 point (slight
Magdolna Tóth, Gitta Ficzek, Ildikó Király, Szilvia Kovács, Mária Hevesi, Júlia Halász, and Zsolt Szani
shape with a moderately ribbed surface ( Fig. 2 ), average height of 7.8 cm, average diameter of 8.4 cm, ratio of height vs. diameter of 0.93, moderate greasiness on the surface, and medium size and density of lenticels. The ground color of the fruits is
Jennifer R. DeEll, Jennifer T. Ayres, and Dennis P. Murr
improve many physiological characteristics of apples, such as reduced ethylene production and respiration, enhanced fruit firmness and acidity retention, and reduced peel greasiness and various physiological disorders ( Blankenship and Dole, 2003 ; DeEll
James P. Mattheis, David R. Rudell, and Ines Hanrahan
, cavitation, soft scald, soggy breakdown, and greasiness) were reported as incidence. Bitter pit was identified as surface lesions <5 mm in diameter with underlying brown, corky tissue. Irregularly shaped peel areas of rough, brown tissue >5 mm were considered
Jennifer R. DeEll, Jennifer T. Ayres, and Dennis P. Murr
reduced superficial scald development, peel greasiness, and various chilling-related disorders ( Bai et al., 2005 ; DeEll et al., 2002 ; Fan and Mattheis, 2001 ; Fan et al., 1999b ; Rupasinghe et al., 2000 ; Watkins and Nock, 2005 ). The efficacy of 1