Use of Phosphite Salts in Laboratory and Semicommercial Tests to Control Citrus Postharvest Decay

Potassium phosphite (KP) concentrations that inhibited the germination of 50% of Penicillium digitatum conidia were 229, 334, 360, 469, 498, or 580 mg/liter at pH 3, 4, 5, 6, 7, or 8, respectively. Increasing phosphate content in media reduced phosphite toxicity. To control green or blue mold, fruit were inoculated with P. digitatum or P. italicum, then immersed 24 h later in KP, calcium phosphite (CaP), sodium carbonate, sodium bicarbonate, or potassium sorbate for 1 min at 20 g/liter for each at 25 or 50°C. Mold incidence was lowest after potassium sorbate, CaP, or KP treatments at 50°C. CaP was often more effective than KP but left a white residue on fruit. KP was significantly more effective when fruit were stored at 10 or 15°C after treatment compared with 20°C. Acceptable levels of control were achieved only when KP was used in heated solutions or with fungicides. KP was compatible with imazalil (IMZ) and other fungicides and improved their effectiveness. KP increased thiabendazole or IMZ residues slightly. Phosphite residues did not change during storage for 3 weeks, except they declined when KP was applied with IMZ. KP caused no visible injuries or alteration in the rate of color change of citrus fruit in air or ethylene at 5 μl/liter.

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Pre- and Postharvest Treatments to Control Green Mold of Citrus Fruit During Ethylene Degreening

Plant Disease ◽

10.1094/pd-90-0089 ◽

2006 ◽

Vol 90 (1) ◽

pp. 89-96 ◽

Cited By ~ 49

Author(s):

J. L. Smilanick ◽

M. F. Mansour ◽

D. Sorenson

Keyword(s):

Sodium Bicarbonate ◽

Color Change ◽

Citrus Fruit ◽

Penicillium Digitatum ◽

Color Removal ◽

Thiophanate Methyl ◽

Green Color ◽

Green Mold ◽

Orange Fruit ◽

High Level

Two approaches, fungicide applications to trees before harvest and drenching fruit after harvest, were evaluated to minimize postharvest green mold, caused by Penicillium digitatum, particularly among fruit subjected to ethylene gas after harvest, a practice termed “degreening” that eliminates green rind color. Preharvest applications of thiophanate methyl (TM) controlled postharvest green mold consistently. In five tests, green mold among degreened orange fruit was 16% when TM was applied 1 week before harvest; whereas, among fruit not treated, the incidence was 89.5%. Thiabendazole (TBZ) applied to harvested fruit in bins before degreening also was very effective. TBZ effectiveness was enhanced by mild heating (41°C), adding sodium bicarbonate, and immersing fruit, rather than drenching them, with the solution. With these measures, an isolate of P. digitatum with a high level of TBZ resistance was significantly controlled. In semicommercial tests with naturally inoculated fruit, TBZ and sodium bicarbonate treatment reduced green mold incidence from 11% among untreated orange fruit to 2%. TBZ residues in lemon fruit at 41°C were about twice those treated at 24°C. Neither TM before harvest nor TBZ and sodium bicarbonate applied after harvest influenced green color removal during degreening of orange fruit. Sodium bicarbonate slightly reduced the rate of lemon color change.

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Evaluation of the use of sodium bicarbonate, potassium sorbate and yeast antagonists for decreasing postharvest decay of sweet cherries

Postharvest Biology and Technology ◽

10.1016/s0925-5214(01)00151-x ◽

2001 ◽

Vol 23 (3) ◽

pp. 233-236 ◽

Cited By ~ 51

Author(s):

Ozgur Akgun Karabulut ◽

Susan Lurie ◽

Samir Droby

Keyword(s):

Sodium Bicarbonate ◽

Potassium Sorbate ◽

Postharvest Decay ◽

Sweet Cherries

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Evaluation of different salts for the control of lettuce varnish spot: when phytotoxicity rules

Canadian Journal of Plant Science ◽

10.1139/cjps-2017-0237 ◽

2018 ◽

Vol 98 (3) ◽

pp. 753-761 ◽

Cited By ~ 4

Author(s):

Maxime Delisle-Houde ◽

Vicky Toussaint ◽

Hicham Affia ◽

Russell J. Tweddell

Keyword(s):

Sodium Bicarbonate ◽

Sodium Carbonate ◽

Sodium Benzoate ◽

Leaf Tissue ◽

In Vitro Assays ◽

Potassium Sorbate ◽

Sodium Metabisulfite ◽

Pseudomonas Cichorii ◽

Foliar Symptoms

Five generally recognised as safe (GRAS) salts with antimicrobial activity were investigated for their potential use as bactericides for the control of lettuce varnish spot [Pseudomonas cichorii (Swingle) Stapp]. The phytotoxicity of salts was first assessed using greenhouse and in vitro assays. Greenhouse assays revealed that salts showed different levels of phytotoxicity. Potassium sorbate, sodium benzoate, and sodium carbonate at higher concentrations caused a noticeable decrease of growth along with foliar phytotoxicity symptoms while sodium metabisulfite and sodium bicarbonate caused exclusively foliar symptoms. Based on the phytotoxic doses 5% determined in vitro, salts can be ranked in ascending order of phytotoxicity as follows: sodium bicarbonate, potassium sorbate, sodium carbonate, sodium benzoate, and sodium metabisulfite. When applied at concentrations causing mild to moderate foliar symptoms of phytotoxicity and no noticeable effect on growth, salts did not significantly affect (p ≤ 0.01) survival of P. cichorii on lettuce leaf tissue and did not significantly reduce (p ≤ 0.01) varnish spot severity. Although sodium metabisulfite was applied at concentrations higher than the minimum inhibitory concentration and minimum bactericidal concentration, it did not affect P. cichorii survival on leaf tissue.

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Control of Postharvest Blue and Green Molds of Oranges by Hot Water, Sodium Carbonate, and Sodium Bicarbonate

Plant Disease ◽

10.1094/pdis.2001.85.4.371 ◽

2001 ◽

Vol 85 (4) ◽

pp. 371-376 ◽

Cited By ~ 119

Author(s):

Lluís Palou ◽

Joseph L. Smilanick ◽

Josep Usall ◽

Inmaculada Viñas

Keyword(s):

Sodium Bicarbonate ◽

Sodium Carbonate ◽

Room Temperature ◽

Hot Water ◽

Penicillium Italicum ◽

Blue Mold ◽

Green Mold ◽

Carbonate Solutions ◽

Immersion Period

Control of citrus blue mold, caused by Penicillium italicum, was evaluated on artificially inoculated oranges immersed in water at up to 75°C for 150 s; in 2 to 4% sodium carbonate (wt/vol) at 20 or 45°C for 60 or 150 s; or in 1 to 4% sodium bicarbonate at room temperature for 150 s, followed by storage at 20°C for 7 days. Hot water controlled blue mold at 50 to 55°C, temperatures near those that injured fruit, and its effectiveness declined after 14 days of storage. Sodium carbonate and sodium bicarbonate were superior to hot water. Temperature of sodium carbonate solutions influenced effectiveness more than concentration or immersion period. Sodium carbonate applied for 150 s at 45°C at 3 or 4% reduced decay more than 90%. Sodium bicarbonate applied at room temperature at 2 to 4% reduced blue mold by more than 50%, while 1% was ineffective. In another set of experiments, treatments of sodium bicarbonate at room temperature, sodium carbonate at 45°C, and hot water at 45°C reduced blue mold incidence on artificially inoculated oranges to 6, 14, and 27%, respectively, after 3 weeks of storage at 3°C. These treatments reduced green mold incidence to 6, 1, and 12%, respectively, while incidence among controls of both molds was about 100%. When reexamined 5 weeks later, the effectiveness of all, particularly hot water, declined. In conclusion, efficacy of hot water, sodium carbonate, and sodium bicarbonate treatments against blue mold compared to that against green mold was similar after storage at 20°C but proved inferior during long-term cold storage.

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Electrolyzed sodium bicarbonate inhibits Penicillium digitatum and induces defence responses against green mould in citrus fruit

Postharvest Biology and Technology ◽

10.1016/j.postharvbio.2015.12.009 ◽

2016 ◽

Vol 115 ◽

pp. 18-29 ◽

Cited By ~ 29

Author(s):

Frida Fallanaj ◽

Antonio Ippolito ◽

Angela Ligorio ◽

Francesca Garganese ◽

Ciro Zavanella ◽

...

Keyword(s):

Sodium Bicarbonate ◽

Citrus Fruit ◽

Penicillium Digitatum ◽

Defence Responses ◽

Green Mould

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Light: An Alternative Method for Physical Control of Postharvest Rotting Caused by Fungi of Citrus Fruit

Journal of Food Quality ◽

10.1155/2020/8821346 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

İbrahim Kahramanoğlu ◽

Muhammad Farrukh Nisar ◽

Chuying Chen ◽

Serhat Usanmaz ◽

Jinyin Chen ◽

...

Keyword(s):

Fungal Pathogens ◽

Light Exposure ◽

Citrus Fruit ◽

Penicillium Digitatum ◽

Solar Light ◽

Special Focus ◽

Penicillium Italicum ◽

Blue Mold ◽

Health Concerns ◽

Green Mold

Solar light has fundamental roles in vast chemical, biochemical, and physical process in biosphere and hence been declared as “source of life.” Solar light is further classified into a broad range of electromagnetic waves, and each region in the solar spectrum bears its unique actions in the universe or biosphere. Since centuries, solar light is believed as a potent source of killing pathogens causing postharvest losses on food products as well as human skin diseases. Citrus fruit crops are widely produced and consumed across the world, but due to their higher juicy contents, Penicillium italicum (blue mold) and Penicillium digitatum (green mold) make their entry to decay fruits and cause approximately 80% and 30% fruit losses, respectively. Agrochemicals or synthetic fungicides are highly efficient to control these postharvest fungal pathogens but have certain health concerns due to toxic environmental residues. Therefore, the scientific community is ever looking for some physical ways to eradicate such postharvest fungal pathogens and reduce the yield losses along with maintaining the public health concerns. This review article presents and discusses existing available information about the positive and negative impacts of different spectrums of solar light exposure on the postharvest storage of citrus fruits, especially to check citrus postharvest rotting caused by Penicillium italicum (blue mold) and Penicillium digitatum (green mold). Moreover, a special focus shall be paid to blue light (390–500 nm), which efficiently reduces the decay of fruits, while keeping the host tissues/cells healthy with no known cytotoxicity, killing the fungal pathogen probably by ferroptosis, but indepth knowledge is scanty. The study defines how to develop commercial applications of light in the postharvest citrus industry.

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Effects of combining hot water, sodium bicarbonate and biocontrol on postharvest decay of citrus fruit

The Journal of Horticultural Science and Biotechnology ◽

10.1080/14620316.2002.11511519 ◽

2002 ◽

Vol 77 (4) ◽

pp. 441-445 ◽

Cited By ~ 42

Author(s):

R. Porat ◽

A. Daus ◽

B. Weiss ◽

L. Cohen ◽

S. Droby

Keyword(s):

Sodium Bicarbonate ◽

Citrus Fruit ◽

Hot Water ◽

Postharvest Decay

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Induction of Resistance to Penicillium digitatum in Grapefruit by the Yeast Biocontrol Agent Candida oleophila

Phytopathology ◽

10.1094/phyto.2002.92.4.393 ◽

2002 ◽

Vol 92 (4) ◽

pp. 393-399 ◽

Cited By ~ 169

Author(s):

S. Droby ◽

V. Vinokur ◽

B. Weiss ◽

L. Cohen ◽

A. Daus ◽

...

Keyword(s):

Citrus Fruit ◽

Pathogen Resistance ◽

Penicillium Digitatum ◽

Yeast Cells ◽

Systemic Resistance ◽

Application Site ◽

Nutrient Competition ◽

Postharvest Decay ◽

Modes Of Action ◽

Candida Oleophila

The yeast Candida oleophila, the base of the commercial product Aspire, is recommended for the control of postharvest decay in citrus and pome fruit. Its modes of action include nutrient competition, site exclusion, and direct mycoparasitism. In the present study, we showed that application of Candida oleophila to surface wounds or to intact ‘Marsh Seedless’ grapefruit elicited systemic resistance against Penicillium digitatum, the main postharvest pathogen of citrus fruit. The induction of pathogen resistance in fruit was already pronounced 24 h after elicitation; it was distance, concentration, and time dependent and restricted to the peel tissue closely surrounding the yeast application site. The induction of pathogen resistance required viable yeast cells at concentrations of 108 to 109 cells ml-1. Nonviable autoclaved or boiled yeast cells or lower yeast concentrations were ineffective in enhancing fruit disease resistance. Application of Candida oleophila cell suspensions to grapefruit peel tissue increased ethylene biosynthesis, phenylalanine ammonia lyase activity, and phytoalexin accumulation, and increased chitinase and β-1,3-endoglucanase protein levels, indicated by western immunoblotting analysis. Scanning electron microscope observations revealed that spore germination and germ tube growth of Penicillium digitatum were markedly inhibited in wounds made near the yeast-treated sites. Overall, this study provides evidence that induced resistance against postharvest decay of citrus fruit should be considered an important component of the multiple modes of action of the yeast Candida oleophila.

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