Preserving Appeal

Preserving Appeal

Fresh Florida citrus is well known for its excellent taste and juiciness. However, peel disorders sporadically develop after harvest that make the fruit unmarketable, or even worse, show up upon arrival at destination markets. These can be difficult to mitigate because a wide range of peel disorders can produce similar symptoms, and we often do not fully understand the underlying cause(s). Resulting economic losses can run into the millions of dollars and reduce buyer confidence for future purchases. Some types of peel breakdown, such as oil spotting (oleocellosis), chilling injury (CI), and one type of postharvest pitting (PP) are easier to mitigate because they are more clearly related to specific harvest or postharvest handling practices. For example, PP has been related to low internal oxygen concentrations within warm (>50°F) fruit coated with waxes that restrict gas diffusion (e.g., some shellac-based waxes). Improved cooling practices and the use of coatings with better gas diffusion have reduced the occurrence of PP. CI is caused by holding fruit at low, but non-freezing temperatures during storage and transit. However, modern handling practices have made CI a rare occurrence on Florida citrus.

Other types of peel disorders, such as stem-end rind breakdown (SERB) and general peel pitting are influenced by both pre- and postharvest factors and their occurrence can vary considerably from one season to the next. While the cause(s) of these disorders are not completely understood, they appear to be most related to the water status of the fruit. They may first appear during the winter months, especially after cool and/or windy weather with low relative humidity (RH), and continue into the spring at the end of the dry season and as field temperatures increase. Tree water stress from the lack of rain or insufficient irrigation before harvest can significantly increase peel breakdown after harvest. Conversely, application of an antitranspirant (e.g., 1% or 2% Vapor Gard) to the trees decreases the permeability of the fruit cuticle to water loss and reduces postharvest peel breakdown.

Health Factors

Plant nutrition, especially low potassium (K), also has been associated with peel disorders in citrus fruit such as creasing and pineapple orange peel pitting. Potassium plays an important role in osmotic (water potential) regulation of cells and in regulating stomatal closing. Recently, we found a single preharvest foliar application of mono-potassium phosphate (0-52-34; 23.5 lb. MKP per acre; 8 lb. K2O per acre) can often significantly reduce postharvest peel breakdown. Thus, before harvest, it is important to maintain an adequate supply of water to the trees and consider a preharvest foliar K or an antitranspirant spray if the block has a history of developing peel disorders.
 
After harvest, drying conditions that promote peel breakdown arise from delays in packing, holding the fruit under low RH and high temperatures, and excessive air movement around the fruit. Studies by Dr. Jacqueline Burns’ group (UF/IFAS) and others worldwide have shown that postharvest fruit exposure to low RH conditions (i.e., 30%) for as little as a few hours, followed by high RH (e.g., 90%) conditions induces peel pitting. Even low RH conditions in the field at harvest can result in greater pitting of the fruit after harvest. Excessive brushing during packing also increases water loss and enhances peel breakdown.

Time And Care

After harvest, the best way to prevent peel breakdown is to minimize the time between harvest and waxing, especially during hot, dry, or windy weather, and to keep the fruit continuously under high RH conditions (>90%). Avoid warm temperatures because even with the same RH, warmer air dries fruit faster. During packing, avoid excessive brushing that increases water loss, keep brush speeds below 100 rpm, and use automatic wipeouts to prevent fruit from sitting idle on the brushes. Cool the fruit as soon as possible and maintain low (but non-injurious) temperatures throughout storage, transport, and marketing.

Leave a Reply

Featured Stories
Protected AgricultureHow To Successfully Produce Vegetables In Controlled Environments
January 28, 2015
Greenhouse expert Merle Jensen offers pointers on growing systems, pest control, plant nutrition, harvesting, and more. Read More
IPMWhat You Need To Know To Maintain An Effective IPM Program In The Greenhouse
January 28, 2015
Greenhouse expert Karin Tifft discusses the importance of scouting, pest identification, control options, and the importance of sanitation. Read More
Apples & PearsPears Get A Hefty Shout-Out From Rapper
January 28, 2015
The pome fruit is on mainstream media's radar thanks to a rapper's quote and ensuing social media blitz. Read More
FruitsHighlights From The Mid-Atlantic Fruit And Vegetable Convention
January 28, 2015
Bio-control use, media literacy, and disease control were just a few of the topics discussed at the convention held in Hershey, PA. Read More
GrapesCalifornia Table Grape Growers Offer Agricultural Scholarships
January 28, 2015
The application deadline for the agricultural scholarships is 5 p.m., Feb. 13. Read More
GrapesNew Wine Hybrid Establishment Cost Resource Available
January 28, 2015
Research from Cornell University breaks down the cost of producing hybrid winegrapes. Read More
FertilizerEasy Access To Fertilization Guidelines
January 28, 2015
New, easy-to-follow brochures take the guesswork out of almond and walnut fertilization. Read More
BerriesDormant Pruning Tips For Your Berries
January 28, 2015
Proper dormant pruning increases berry size and improves overall health of blackberry and raspberry plants. Read More
NutsHow Freezing Temperature Affect Bearing and New Trees
January 28, 2015
Key points before and after the critical bloom period make exposure to freezing temperatures relevant. Read More
CitrusFlorida Citrus Is Still A Big Deal [Opinion]
January 28, 2015
Even while in the grips of greening, citrus continues to be a big contributor to the Sunshine State's economy. Read More
The Latest
Protected AgricultureHow To Successfully Produce Vegetables In Controlled En…
January 28, 2015
Greenhouse expert Merle Jensen offers pointers on growing systems, pest control, plant nutrition, harvesting, and more. Read More
IPMWhat You Need To Know To Maintain An Effective IPM Prog…
January 28, 2015
Greenhouse expert Karin Tifft discusses the importance of scouting, pest identification, control options, and the importance of sanitation. Read More
Apples & PearsPears Get A Hefty Shout-Out From Rapper
January 28, 2015
The pome fruit is on mainstream media's radar thanks to a rapper's quote and ensuing social media blitz. Read More
FruitsHighlights From The Mid-Atlantic Fruit And Vegetable Co…
January 28, 2015
Bio-control use, media literacy, and disease control were just a few of the topics discussed at the convention held in Hershey, PA. Read More
GrapesCalifornia Table Grape Growers Offer Agricultural Schol…
January 28, 2015
The application deadline for the agricultural scholarships is 5 p.m., Feb. 13. Read More
GrapesNew Wine Hybrid Establishment Cost Resource Available
January 28, 2015
Research from Cornell University breaks down the cost of producing hybrid winegrapes. Read More
FertilizerEasy Access To Fertilization Guidelines
January 28, 2015
New, easy-to-follow brochures take the guesswork out of almond and walnut fertilization. Read More
BerriesDormant Pruning Tips For Your Berries
January 28, 2015
Proper dormant pruning increases berry size and improves overall health of blackberry and raspberry plants. Read More
NutsHow Freezing Temperature Affect Bearing and New Trees
January 28, 2015
Key points before and after the critical bloom period make exposure to freezing temperatures relevant. Read More
CitrusFlorida Citrus Is Still A Big Deal [Opinion]
January 28, 2015
Even while in the grips of greening, citrus continues to be a big contributor to the Sunshine State's economy. Read More
FruitsUSDA Forecast Predicts Normal Water Supply For Parts Of…
January 27, 2015
The Southwest, Sierra Nevada region, and Pacific Northwest are starting the year drier than normal. Read More
Apples & PearsThe Story Of Honeycrisp Is One Of Challenges And Succes…
January 27, 2015
‘Everything’s different’ in this world of 150 million 40-pound box world of apple growing. Read More
BerriesWhy You Should Be Growing Black Raspberries
January 27, 2015
Amazing health benefits for consumers and production and marketing benefits for the grower make this berry a must-consider option for your operation. Read More
Apples & PearsThe Dark side Of Honeycrisp
January 27, 2015
Growers say there’s a love-hate relationship with America’s darling apple. Read More
Apples & PearsExpanded Market Access For U.S. Grown Apples To China
January 26, 2015
Agreement expected to boost apple exports by $100 million per year. Read More
CitrusNominees Sought For Florida Agricultural Environmental …
January 26, 2015
Honor recognizes those developing and adopting environmentally innovative farming practices. Read More
CitrusIncreased Global Trade Opportunity Equals New Threats F…
January 26, 2015
Despite expanding business abroad, Florida Agriculture Commissioner Adam Putnam says he's confident in the protocols in place to prevent entry of invasive pests and disease. Read More
GrapesEstimates Vs. Actual: The Cost Of Installing A Vineyard
January 26, 2015
The true costs of developing a vineyard depend on variables such as vine selection, trellising, and labor. Read More