the xylem ( White, 2001 ; White and Broadley, 2003 ). A physiological disorder termed “shoot-tip necrosis” observed in in vitro culture of potato ( Solanum tuberosum ) has been hypothesized to be a calcium deficiency symptom ( McCown and Sellmer, 1987
Senay Ozgen, James S. Busse, and Jiwan P. Palta
Robert Bevacqua, Eugene Mielke, Timothy Facteau, Ruth Lavon, and Paul Chen
. This work was supported by a Binational U.S.-Israel Agricultural Research and Development (BARD) grant for the study of disorders of fruit. We thank Anita Miller, Tony Chen, and Jim Bagget, for their reviews of the manuscript. The cost of publishing
Bernard Bible and Richard McAvoy
Poinsettia (Euphorbia pulcherrima Willd. ex Klotzch) bracts are susceptible to postharvest disorders like the pathogen Botrytis cinerea and the abiotic disorder bract necrosis that degrade plant appearance. `Freedom Red' and `Supjibi' poinsettias were grown hydroponically with Ca concentrations of 0.5 or 4 mm. Forty days after initial anthesis, plants were harvested and their bracts subdivided into true-bracts and transitional-bracts for determination of incidence of botrytis lesions and bract necrosis. Mineral nutrients in bract margins were determined only for true-bracts. Margin Ca concentrations were relatively high in true bracts only for `Supjibi' plants exposed to 4 mm Ca solutions. Botrytis incidence was increased for transitional-bracts but not true-bracts for both cultivars by plant exposure to low (0.5 mm) Ca solutions compared to control (4 mm Ca) plants. The smaller the poinsettia roots relative to shoots, the higher the incidence of botrytis for `Freedom Red' transitional-bracts and `Supjibi' true-bracts. Botrytis incidence was higher on transitional-bracts (13%) than on true-bracts (3.5%) for both cultivars exposed to low Ca, whereas the incidence of bract necrosis on `Supjibi' was the same on true-bracts and transitional-bracts in either Ca solution. Bract necrosis was not evident on `Freedom Red' plants in either the 0.5 or 4-mmmm Ca solutions, however for `Supjibi' exposure to low Ca solutions increased incidence of bract necrosis from 5.5% for controls to 19.3%. The effect of Ca stress applied to poinsettia roots was genotype dependant for bract necrosis but not for botrytis.
Bernard Bible and Richard McAvoy
Incidences of poinsettia (Euphorbia pulcherrima Willd. ex Klotzch) bract disorders like the pathogen Botrytis cinerea and the abiotic disorder bract necrosis are related to nutrient stress. `Supjibi' poinsettias were grown hydroponically with four Ca-B combinations of 0 or 4 mm Ca added with either 5 or 120 μmol B added. Forty-one days after initial anthesis, plants were harvested and their bracts subdivided into true-bracts and transitional-bracts for determination of incidence of botrytis lesions and bract necrosis. Mineral nutrients in bract margins were determined for leaves, transitional-bracts and true-bracts. Leaf margins had the highest concentrations of Ca and B. Margins of transitional-bracts had substantially lower concentrations and margins of true-bracts the least. The low Ca (0 mm) or low B (5 μmol) treatments greatly reduced the concentrations of these elements, respectively, in all three tissue types. The low Ca-low B treatment increased the incidence of bract necrosis on true-bracts from 1.9% on controls (4 mm Ca, 120 μmol B) to 27%. Low Ca treatment increased bract necrosis on transitional-bracts from 1.6% on controls to 24.3%. Bract necrosis incidence was the same on true-bracts and transitional-bracts, whereas the incidence of botrytis was higher on transitional-bracts than on true-bracts. Botrytis incidence was increased for true-bracts and transitional-bracts by plant exposure to low Ca solutions compared to plants in 4 mm Ca. Low Ca reduced growth in roots, but not shoots. Ca and B stress to roots increased the incidence of bract necrosis on true-bracts, while only Ca stress increased incidence of botrytis.
George M. Greene II
The apple cultivar Enterprise is a product of the Purdue–Rutgers–Illinois (PRI) disease-resistant apple breeding program. It has field immunity to apple scab, has a high level of resistance to cedar apple rust and fire blight, and is moderately resistant to apple powdery mildew. This resistance to these diseases makes the production of this cultivar desirable, especially on the popular fire blight-susceptible M.26 rootstock. Compared to many other scab-resistant cultivars, `Enterprise' has performed well in the mid-Atlantic area. However, this cultivar has been reported to be susceptible to low-Ca disorders when grown in New Jersey and Virginia. The mid-Atlantic area is notorious for the production of fruit with high levels of corking and bitter pit. This may be due to factors such as vigorous tree growth and low transpirational flow, which may be weather-related. Circumstantial evidence based on the production of clean `Enterprise' at Biglerville, Pa., where moderately high rates of CaCl2 have been applied in cover sprays, indicate that this disorder may be a Ca deficiency symptom. A replicated trial of many scab-resistant cultivars was established in 1990, 1991, and 1992. Due to the common incidence of low-Ca disorders, CaCl2 has been added to the cover spray program that is applied for insect control. Low-Ca disorders have never been seen in fruit produced at Biglerville, and the cover spray program applied 67 and 73 kg·ha–1 of CaCl2 (77% to 80% CaCl2, flake) in 1993 and 1994, respectively.
Raquel Gomez and Lee Kalcsits
contributes to cell death, which produces dark lesions associated with bitter pit. High incidences of calcium-related disorders are associated with rapid cell expansion such that the demand for calcium exceeds the supply to the fruit because calcium uptake and
Yan-xin Duan, Ying Xu, Ran Wang, and Chun-hui Ma
prohexadione calcium use Pesqui. Agropecu. Bras. 47 939 947 Hayama, H. Mitani, N. Yamane, T. Inoue, H. Kusaba, S. 2017 Characteristics of cork spot like disorder in Japanese pear ‘Akizuki’ and ‘Oushuu’ Hort. Res. (Japan) 16 1 79 87 Ho, L.C. Hand, D.J. Fussell
M.E. El-Mahrouk, A.R. El-Shereif, Y.H. Dewir, Y.M. Hafez, Kh. A. Abdelaal, S. El-Hendawy, H. Migdadi, and R.S. Al-Obeed
high-quality and pathogen-free planting materials and reducing production costs. Hyperhydricity has been described as a physiological disorder of tissue-cultured plants whereby the hyperhydric propagules become translucent due to excessive hydration of
Jared Barnes, Brian Whipker, Ingram McCall, and Jonathan Frantz
purposes. The differences in the specificity of the roles and accompanying nutritional disorders are illustrated with N and Ca deficiencies. An important component of amino acids, proteins, and nucleic acids ( Briskin and Bloom, 2010 ), N is able to be
Lee Kalcsits, Gregory van der Heijden, Michelle Reid, and Katie Mullin
Ontario Factsheet. Ministry of Agriculture, Food and Rural Affairs. 2 July 2017. < http://www.omafra.gov.on.ca/english/crops/facts/00-009.htm > de Freitas, S.T. Mitcham, E.J. 2012 Factors involved in fruit calcium deficiency disorders Hort. Rev. 40 107 146