Stylar End Rot Information – Managing Fruit With Stylar End Rot

By: Mary Ellen Ellis

Citrus fruits, most often navel oranges and lemons, can be damaged by a disease called stylar end rot or black rot. Protect your citrus crop by creating an environment for healthy fruit to develop.

What is Stylar End Rot?

Stylar end rot is also called black rot in navel oranges, but is also sometimes referred to as Alternaria rot. The stylar is the end of the fruit that we usually call the naval. When the stylar is cracked or damaged, an infection can get in that causes the damage and rot.

Stylar end breakdown causes include a few different pathogens of Alternaria citri. Unhealthy or damaged fruit is susceptible to the infection. The infection may occur while the fruit is still on the tree, but much of the resulting rot and decay occurs while the fruit is in storage.

Symptoms of Stylar End Rot

Fruit that have been infected with this fungus may start to change color prematurely on the tree, but you may not see the more obvious signs until you have harvested the fruit. Then, you may see darker spots at the stylar end of the fruit. If you cut into the fruit, you will see rot that may penetrate right to the center.

Preventing Fruit with Stylar End Rot

Once you see the end rot in your fruit, it is too late to save it. But, with complete stylar end rot information, you can take steps to prevent the infection. Stylar end rot is most common in fruits that are not healthy or that have been stressed.

If you can provide your citrus trees with the best growing conditions and take steps to manage stress, you can prevent the disease: well-drained soil, plenty of sun, occasional fertilizer, adequate water, and pest control.

Fungicides used preventatively have not been shown to work.

Stylar End Breakdown in Limes

A similar phenomenon is described in limes, in which limes left on the tree too long develop yellow to brown decay at the stylar end. This is not attributed to the Alternaria pathogen. Instead, it is simply over-ripening and rotting. It happens if you let your limes stay too long on the tree before harvesting them. To avoid, simply harvest your limes when they are ready.

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Read more about Citrus Trees

There are four common varieties of limes: Mexican lime (also known as key limes), Tahiti lime (also known as Persian lime), giant key lime and Rangpur lime (typically used as root stock for lime trees).

Lime trees need to be planted on the southern side of your home for wind protection. The location should be sunny with well-drained soil.

Mature trees need to be watered every other week. Ammonium sulfate should be applied every four months as fertilizer. Mulch 1 foot around the base of the tree to keep grass from growing around the base.

  • Lime trees produce a small green fruit that is high in vitamin C, tastes sour and is acidic in nature.
  • Lime trees need to be planted on the southern side of your home for wind protection.

Tahiti Lime

Citrus latifolia Tan.

  • Description
  • Origin and Distribution
  • Varieties
  • Climate
  • Soil
  • Propagation
  • Culture
  • Harvesting
  • Yield
  • Storage
  • Pests and Diseases
  • Food Uses
  • Toxicity
  • Other Uses

This acid lime lacks the long history and wide usage that glamorize the small Mexican lime. Its identity has been in doubt and only in recent years has it been given the botanical name, Citrus latifolia Tan. An alternate common name is Persian lime.

Fig. 43: Tahiti, or Persian lime ( Citrus latifolia ) (left) and the Mexican, or West Indian ( C. aurantifolia ) which is especially aromatic.

The Tahiti lime tree is moderately vigorous, medium to large, up to 15 or 20 ft (4.5-6 m), with nearly thornless, widespread, drooping branches. The leaves are broad-lanceolate, with winged petioles young shoots are purplish. Flowers, borne off and on during the year but mainly in January, are slightly purple-tinged. The fruit is oval, obovate, oblong or short-elliptical, usually rounded at the base, occasionally ribbed or with a short neck the apex is rounded with a brief nipple 1 1/2 to 2 1/2 in (4-6.25 cm) wide, 2 to 3 in (5-7.5 cm) high peel is vivid green until ripe when it becomes pale-yellow smooth, thin, tightly clinging pulp is light greenish-yellow when ripe, in 10 segments, tender, acid, but without the distinctive bouquet of the Mexican lime usually seedless, rarely with one or a few seeds, especially if planted among a number of other Citrus species. The Tahiti lime flowers have no viable pollen.

The origin of the Tahiti lime is unknown. It is presumed to be a hybrid of the Mexican lime and citron, or, less likely, the lemon, and it is genetically a triploid though only the normal 18 chromosomes have been reported. Dr. Groff, in a reference to Citrus aurantifolia in his "Culture and Varieties of Siamese Pummelos . . . ", said: ". . .it is represented by a large variety known as Manow klom and by a small one known as Manow yai." One might speculate as to whether the large variety might be the female parent of the Tahiti lime. At any rate, it is believed that the Tahiti was introduced into the Mediterranean region by way of Iran (formerly called Persia). It is said that, for some centuries, a virtually identical lime called 'Sakhesli' has been cultivated on the island of Djerba off the coast of Tunisia, and that the local name means "from Sakhos", an old Arabic name for Chios, a Grecian island. Portuguese traders probably carried it to Brazil, and it was apparently taken to Australia from Brazil about 1824. It reached California from Tahiti between 1850 and 1880 and had arrived in Florida by 1883. It was being grown at Lake Placid in 1897. This lime was adopted into cultivation in California but is not extensively grown there, the bulk of California's lime crop being mainly the Mexican lime. In Florida, the Tahiti quickly took the place of the more sensitive small lime and the lemon. Following World War I, the Tahiti lime became a well-established commercial crop. At first, there was market resistance, buyers viewing the Tahiti lime as a "green lemon", and, for some time, Canadians would not accept it because they were accustomed to the more flavorful Mexican lime. In the 1930's, many Florida citrus growers planted limes for extra income and, in 1949, the development of limeade concentrate provided further impetus to the Tahiti lime industry.

In 1954, Libby, McNeil & Libby topworked 100 acres (40 ha) of grapefruit trees in Florida to Tahiti lime. Production increased 60% from 1970 to 1980. In 1979, the total crop was valued at close to $9 million. Nearly 1 million bushels (250 limes per bushel) were shipped fresh and the same amount was processed. By 1980, there were approximately 8,000 acres (about 3,250 ha) of commercial groves. Five years later, Dade County shipped 110 million lbs (50 million kg) of fresh fruit worth about $14 million to the growers, from a total of 6,500 acres (2,630 ha). Florida produces 90% of the national crop, for marketing fresh and for canned lime juice, frozen lime juice, frozen lime juice concentrate, frozen limeade and powdered lime juice. The Florida Lime and Avocado Administrative Committee conducts research on production and carries on national promotional activity.

There have been only a few named cultivars, or alleged cultivars, of the Tahiti lime:

'Bearss' ('Bearss Seedless', 'Byrum Seedless')–This was first put forward as a new variety of Tahiti lime originating in the grove of T.J. Bearss at Porterville, California, in 1895. It was described and illustrated in 1902 and cultivated and catalogued by the Fancher Creek Nursery Company in 1905. It was grown in California, Arizona and Hawaii under the name, 'Bearss', at least until the late 1940's. However, comparative studies made in California led to the decision that the 'Bearss' did not differ sufficiently from the typical Tahiti lime to be maintained as a distinct cultivar.

'Idemor' –a limb sport found around 1934 in a grove owned by G.L. Polk in Homestead, Florida, and patented in 1941 (U.S. Plant Patent #444). The fruit is smaller and more rotund than the typical Tahiti. A very similar sport has been reported from Morocco. This lime is no longer planted because of its susceptibility to virus diseases.

'Pond' –In 1914, budwood was obtained by Dr. H.J. Webber from a Tahiti lime tree in the Moanalua Gardens, in Honolulu. Budded trees bore fruits that were somewhat smaller than the typical Tahiti but otherwise much the same. The trees were somewhat lower growing. This cultivar seems to have disappeared.

USDA 'No. 1' and 'No. 2'–selections from many seedlings grown by Dr. James Childs of the United States Department of Agriculture at the Horticultural Field Station, Orlando, Florida. They are free of exocortis and xyloporosis viruses and are available to growers through Florida's Budwood Registration Program. The fruit does not differ significantly in character from the typical Tahiti lime. The development of these virus-free clones has been a great boon to Florida's lime industry.

The Tahiti lime is hardier than the Mexican lime and better adapted to the mainland of Florida. Most of the commercial groves are in Dade County, but, with some cold protection, this lime can be grown on the east and west coasts and the central ridge as far north as Winter Haven. Even in southern Florida, drastic drops in temperature have made it necessary to protect lime groves with wind machines or overhead sprinkling,

The plantings in southern Florida are on oolitic limestone. Those further north are on deep sand. The soil must be well drained. In low land subject to standing water, lime trees are planted on elevated beds.

The seeds of the Tahiti lime are largely monoembryonic few seeds are available for planting and seedlings, for the most part, are exceedingly variable. Only 10 trees of 114 seedlings grown at the Agricultural Research and Education Center of the University of Florida, Homestead, showed typical Tahiti lime characters vegetatively and in the fruit, except for long thorns on the trunk and branches.

This lime has been customarily budded onto rough lemon, but in recent years more commonly on the alemow, C. macrophylla . Many sweet orange and grapefruit trees have been successfully topworked to the Tahiti lime. Today, 40% of the commercial Tahiti lime trees have been grown from air-layers.

In Dade County's limestone, the trees are planted at the intersection of mechanically-cut trenches 16 in (40.5 cm) deep, or on mounds of crushed limestone and soil on scarified ground. The Tahiti lime tree is less vigorous than the Mexican lime and accordingly lends itself to close-planting. Spacing may be as close as 10 or 15 ft (3-4.5 m) in rows 20 ft (6 m) apart, which permits about 150 to 200 trees per acre (60-80/ha). When the trees overlap, they are mechanically hedged and topped. Greater yields will result if the trees are spaced at 20 ft (6 m) and hedging and topping are performed at 2 -to 3 -year intervals. The tree produces few water sprouts. A 12-month study in Cuba showed that hedging does not affect yield a year later, and does not alter the normal growth of the tree.

Air-layered trees begin to bear a year before budded trees but, as they mature, they generally do not yield as well. Because of their year-around growth, lime trees demand more fertilization and irrigation than other Citrus species. In commercial groves, irrigation is provided by overhead sprinklers, portable or stationery.

In early days, many trees were afflicted with bark lesions and even girdling, killing the affected branches or the entire tree if on the trunk. Splitting high-nitrogen fertilizer applications into 4 applications annually instead of 2 seemed to eliminate the problem. More recently, it has been recommended that a 4-6-6 formula of NPK be applied every 60 days. Potash is particularly important in relation to yield. In California, experimental spraying with gibberellic acid (10 ppm) delayed maturity and increased fruit size. The fruit stayed green longer in the packinghouse.

Tahiti limes are harvested 8 to 12 times a year–once a month in winter, but 70% of the crop matures from May to fall. The peak period is July to September. The demand persists year-around and off-season fruits sell at premium prices. Most harvesting is by hand but some use a "gig". If picked too immature, the fruits will be deficient in juice. Since 1955, a Federal Marketing Order has prevented the harvesting of immature fruit and has provided for the industry's setting of standards of quality, grade and size. The minimum permissible juice content is 42%. If left too long on the tree, the fruits will be subject to stylar-end-breakdown and are apt to turn yellowish before they reach distant markets.

The limes are collected in wooden field boxes and conveyed by truck to packinghouses where they are graded, washed, waxed, and packed in 10-,20-,40-,or 55-lb (4.5-,9-,18-,or 25-kg) corrugated cartons for shipment to retailers. About 40% of the crop is processed locally for lime juice concentrate. Cull limes are shipped to out-of-state manufacturers of citrus juices and peel oil extractors. Limes for shipment to Hawaii and Arizona must be fumigated with methyl bromide because of possible infestation by Caribbean fruit fly.

The yield from 7 ft (2.13 m) trees grafted on alemow rootstock has averaged 90 lbs (41 kg), while trees of the same size on rough lemon yielded 63 lbs (29 kg). Under advanced methods of management, Florida lime groves produce 600 bushels per acre (243 bu/ha) annually.

The Tahiti lime requires no curing. The fresh fruits remain in good condition for 6 to 8 weeks under refrigeration.

The citrus red mite (purple mite, red spider, spider mite), and the broad mite may heavily infest Tahiti lime leaves and fruits.

Formerly, the trees and fruits commonly evidenced lime blotch (yellow areas on leaves and fruits) but the replacing of susceptible trees has largely eliminated this problem. The tree is immune to withertip, moderately susceptible to scab and greasy spot. Red alga is a major problem, causing bark splitting and dieback of branches. It can be prevented by regular and thorough spraying with copper or other suitable fungicides. The tree is subject to several viruses: crinkly leaf, psorosis, tatterleaf , tristeza, exocortis and xyloporosis.

The fruits are highly subject to oil spotting (oleocellosis), which occurs most frequently during rainy seasons and when limes are harvested when wet with dew. Stylar-end-breakdown, or stylar-end-rot, has been a very serious post-harvest disorder in the summer. It may develop within 2 hours after picking or several days later. It is apparently induced in oversize fruits, larger than 2 1/2 in (6.25 cm) picked early in the morning when internal pressure is high and left too long in the hot sun in the field boxes. The effect is an expansion and rupturing of juice vesicles and the development of a brown, soft area at the apex of the fruit, occasionally at the base also. Fruit losses have been as high as 40%. Precooling the fruits for 24 hours greatly reduces the incidence of this disease.

The Tahiti lime is utilized for making limeade and otherwise for the same purposes as the Mexican lime. In Florida, a wedge of lime is commonly served with avocado, and lime juice is frequently used as an alternative to vinegar in dressings and sauces.

It was formerly held that the oil from the peel of the Tahiti lime was of inferior quality. Since the late 1960's, it has been accepted by the trade and produced in quantity as a by-product of the juice -extraction process. It is utilized for enhancing lime juice and for most of the other purposes for which Mexican lime peel oil is employed.

Excessive exposure to the peel oil of the Tahiti lime may cause dermatitis. Rolling the limes between the hands before squeezing in order to extract more of the juice will coat the hands with oil and this will be transferred to whatever parts of the body are touched before washing the hands. Subsequent exposure to sunlight often results in brown or red areas that itch intensely, and sometimes severe blistering. The sap of the tree and scratches by the thorns may cause rash in sensitive individuals.

Lime juice is employed as a rinse after shampooing the hair. Light streaks have been bleached in the hair by applying lime juice and then going out into the sun for a time. One should be sure that there is no peel oil on the hands when doing this. Lime juice has been applied on the face as a freshening lotion. Some Florida housewives use lime juice for cleaning the inside of coffeepots, and grind a whole lime in the electric garbage-disposal to eliminate unpleasant odor. Dilute lime juice will dissolve, overnight, calcium deposits in teakettles.

Medicinal Uses: Lime juice, given quickly, is an effective antidote for the painful oral irritation and inflammation that result from biting into aroids such as Dieffenbachia spp., Xanthosoma spp., Philodendron spp., and their allies. Lime juice has also been applied to relieve the effects of stinging corals.

What Is Stylar End Rot: Common Stylar End Breakdown Causes - garden

This is a fungal disease also know as leaf blight. It typically affects plants in the spring season, due to cool, wet conditions. It can be identified by the dark colored legions found on the undersides of leaves that must then be removed. Dryer, hotter weather can stop the spread of anthracnose.

Black Heart

Black heart is a quality problem that affects potatoes when they are deprived of oxygen. High temperatures and excess water in the soil contribute to this condition in the field. Potatoes can also develop this problem in transit or storage if they are exposed to very hot or very cold temperatures.

Bloom Drop

Bloom drop, or as it’s sometimes called—blossom drop, is when the bloom or flower of a vine crop (cucumbers, melons, gourds, and tomatoes to name a few) drops off, preventing the plant from producing fruit. Once the flower is pollinated, the plant grows a cucumber or tomato (or whatever type of plant it is) in that location. If the bloom falls off, nothing can grow.

The most frequent cause of this problem is inclement growing conditions (extreme hot or cold temperatures, high winds, or torrential rainfall). Commercial growers work on very set schedules, so when freezing temperatures cause the majority of a crop to experience bloom drop, the entire harvest is delayed until new flowers appear and new fruit has time to mature. This often creates a future supply gap and drives up market prices.

For more information about bloom (or blossom) drop, see Purdue and University of Florida.

Bottom Rot

Caused by the fungus Rhizoctonia solani, bottom rot is identified by sunken, reddish-brown spots on the bottom of plants, most notably, lettuces. If the fungus only affects the outer leaves they can be trimmed, but if it has invaded whole heads, they cannot be used. The spots most typically occur when leaves touch soil that contains the fungus and when temperatures are high and air is humid.


Bracketing is a cosmetic defect caused by inconsistent growth in broccoli plants. It typically occurs when there are large swings in temperatures, resulting in growth being stopped then started rapidly. The biggest problem caused by bracketing is that it prevents crowns from being trimmed to a short- or Asian-cut crown length. If the crown were to be cut, the florets would fall off the stalk.

Brix Levels

The Brix scale was named for a 19th century German named A.F.W. Brix. This system is used in the United States to measure the sugar content in fruit, most notably citrus, grapes, and melons.


A pathogen that invades the lining of the small intestine. C. jejuni is the most commonly-isolated species.

  • Fever
  • Severe abdominal cramps
  • Bloody diarrhea

  • Young children
  • The elderly
  • The immunocompromised

  • Contaminated food typically undercooked poultry or water
  • Occasionally through person-to-person contact
  • Examples:
    • If infected person does not wash his/her hands properly after using the toilet, can be passed along by physical contact or by handling food
    • If contaminated water (through human or animal feces) touches food at any stage (irrigation, washing, rinsing, etc.), contamination can also occur

Clostridium Perfringens

Clostridium perfringens or C. perfringens is the third most common cause of foodborne illness in North America, causing an estimated one million cases per year. These spore-forming bacteria can be found as a normal component of decaying plant life, marine sediment, soil, and in the intestinal tract of many animals, including humans.

They prefer environments with little to no oxygen and typically cause illnesses when large quantities are ingested through inadequately cooked meat and poultry or in prepared food that has been left at the wrong temperature for too long. These bacteria thrive between 40-140˚F (aka the danger zone) they cannot grow at proper refrigerator or freezer temperatures.

Symptoms include abdominal cramping, diarrhea, vomiting, and fever. It cannot be passed from one person to another. Most occurrences resolve themselves within 24 hours, but extreme cases of Type C can result in death.

Young children, pregnant women, the elderly, and immunocompromised persons are most at risk, but given the right conditions, anyone can suffer this illness.

Cold Chain Management

Cold chain management is the control and maintenance of storage temperatures to prevent product deterioration and bacteria growth, as well as to prolong shelf-life it is the management of the real-time series of events that occur from seed to fork.

The cold chain combines all of the links between transport and storage

  • From harvest point to transportation (refrigerated trucks)
  • Transportation to production or shipping facilities
  • Production/shipping facilities to distribution warehouses
  • Distribution warehouses to foodservice operators' coolers
  • Storage inside foodservice operators' coolers until time of plating


In 1914, the Public Health Service first used coliform as a general name to indicate members of the Enterobacteriaceae family, a broad class of indicator microorganisms. Coliforms can be used to show the presence of more dangerous disease-causing bacteria or viruses. They can also be found in the intestinal tracts of humans and animals, feces, water, soil, and vegetation.

Coliforms are normally present on raw plants positive testing for them does not necessarily indicate the produce has come in contact with feces.

Are All Coliforms Dangerous?

  • There are many types of coliforms, not all make people sick, but some do
  • Since there are so many types, exposure has effects varying from nothing to serious illnesses

  • Frequently spread in hospital environments
  • Fruits or vegetables may become contaminated from soil or manure fertilizers during growing or harvesting periods
  • Contaminated water can pass bacteria if it touches food at any stage (irrigation, washing, rinsing, processing, etc.)

Cryptosporidium Parvum

Cryptosporidium parvum, also known as crypto, is a microscopic protozoa that can cause a parasitic disease in the intestines of mammals, including humans. It is considered the most significant waterborne pathogen in developed countries. In fact, it sickened 403,000 people in Milwaukee, Wisconsin in 1993. The protozoa itself is protected by a thick outer shell that keeps it alive outside the body for long periods it is also chlorine resistant.

Cryptosporidium is typically spread by drinking contaminated water, eating infected food, or being contaminated by feces. It only takes two to ten cryptosporidium parasites to cause infection.

Symptoms include acute, non-bloody diarrhea, nausea, vomiting, abdominal pain, fatigue, and loss of appetite.

Young children, pregnant women, the elderly, and immunocompromised persons are most at risk, but given the right conditions, anyone can suffer this illness.

Cured/Fresh-Run Onions

Fresh-run onions exhibit light color and flaky skin expect typical cured storage-onion characteristics to include globe-like shape, firm texture, dark skin, and single centers.


A one-celled parasite spread by water or food contaminated with infected feces.

  • Severe abdominal cramps and diarrhea
  • Loss of appetite and substantial weight loss
  • Bloating, gas, nausea
  • Vomiting, fever, and fatigue

  • All ages are at risk for infection

  • Contaminated food or water

Double Centers

A double center is a term used when two onions grow from one root. This is typically undesirable in the commercial market, as it makes it more difficult to cut onions into rings or consistent slices.

E. coli

  • An abbreviation for the bacterium Enterobacteriaceae family called Escherichia coli
  • "Escherich" was the scientist who isolated the bacteria in 1885
  • Many types exist—some healthy, some dangerous the most common harmful strain is E. coli 0157:H7
  • Organisms are harbored in animal and human feces
  • The most common sources are ground beef and raw milk less commonly found in produce

  • Severe abdominal cramps
  • Bloody diarrhea
  • Possible organ damage and/or death

  • Young children
  • Elderly and/or immunocompromised persons

  • Contaminated food or water
  • Person-to-person contact
    • Examples:
    • If an infected person does not wash his/her hands properly after using the toilet, bacteria can be passed by physical contact or by handling food
    • If water contaminated with E. coli (through animal or human feces) touches food at any stage (irrigation, washing, rinsing, etc.), the food may also become contaminated


Enterococcus are naturally occurring intestinal bacteria that can be found in humans, animals, plants, soil, and water. It is one of the most commonly occurring hospital-acquired illnesses, but can also be a foodborne illness. Enterococcus faecalis is the most commonly-isolated species.

  • Fever
  • Urinary tract infection
  • Diarrhea
  • Diverticulitis
  • Meningitis (rare)

  • Young children
  • The elderly
  • The immunocompromised

  • Most frequently spread in hospitals
  • Can be spread through contaminated plants, soil, and water
  • Occasionally through person-to-person contact
    • Examples:
    • If an infected person does not wash his/her hands properly after using the toilet, it can be passed along by physical contact or by handling food
    • If contaminated water touches food at any stage (irrigation, washing, rinsing, etc.), contamination can also occur

Epidermal Peeling

Usually used in reference to lettuces, epidermal peeling is a quality defect caused by freezing temperatures. The outer layer of the leaf peels away, much like chapped lips. It is a purely cosmetic defect and does not affect flavor or quality.

Escherichia Coli (Non-O157 Shiga Toxin-Producing)

E. Coli is broadly classified by O and H antigens. For instance, the most well-known E. Coli strain is O157:H7. Outbreaks involving non-O157 Shiga toxin-producing E. Coli (STEC) are rarer (or perhaps under-reported), but have been increasing since the 1990s.

The bacterium can be spread person to person or by contaminated foods. The major source for humans is cattle feces.

Symptoms are similar to those involved in E. Coli O157 (abdominal cramping, bloody diarrhea, and possible organ damage), but can also include hemolytic uremic syndrome (HUS), a life-threatening complication that can cause kidney failure. Incubation can take as long as ten days or as few as one.

Young children, pregnant women, the elderly, and immunocompromised persons are most at risk, but given the right conditions, anyone can suffer this illness.

Ethylene Gas

Ethylene is an odorless, colorless gas that is produced naturally by fruits and vegetables. It can increase the pace at which fresh produce ripens, shortening shelf-life.

Some of the highest producers of ethylene are apples, avocados (ripe), bananas, cantaloupe, kiwi fruit, pears, and stone fruit.

Almost all fresh produce is at least somewhat sensitive to ethylene gas. In storage, be sure to isolate the high producers from the rest of your fruits and vegetables.

Food Security

Food security refers to the monitoring and inspection of our food supply to reduce its vulnerability to targeted attacks. Areas covered include domestic production, imports, and distribution. Additional regulation of these activities is currently under consideration.

  • Bioterrorism is the act of any individual, group, or government to spread disease pathogens with the intent to harm others.
  • Many now believe that terrorists could attack the US food supply.

The Department of Homeland Security

  • The Department of Homeland Security includes the Coast Guard, Customs Service, Immigration and Naturalization Service, Border Patrol, Secret Service, Federal Emergency Management Agency, and the Transportation Administration.
  • The CIA and FBI (reporting to the Department of Justice) are separate organizations.

Genetically Modified Organisms

What are Genetically Modified Organisms?

A genetically modified organism (GMO) is any item that has been altered at the molecular level.

In agriculture, GMOs are typically created in order to boost yields, improve quality, and repel insects.

  • An international panel of scientists found that genetically altered crops are as safe as traditional crops.
  • Genetic modification allows crops to be grown with additional vitamins and nutrients.
  • Crops can also be engineered to repel certain insects.
  • Foods might be grown in places that are today ridden with drought or floods.

  • Many scientists believe that GMOs increase new toxins and allergens in foods.
  • May increase the use of chemicals.
  • May create herbicide-resistant weeds.
  • May disturb the ecological balance.

Good Agricultural Practices (GAP)

Good Agricultural Practices, or GAPs, are the FDA guidelines for minimum sanitary and safety requirements to be used while growing and harvesting crops. These requirements include the areas of:

  • Site selection
  • Manure handling
  • Irrigation methods
  • Equipment, field, and storage sanitation
  • Worker hygiene and training
  • Proper storage temperature maintenance

For example, before a farmer begins planting crops, he/she will create a blueprint of the specific practices needed to maintain the safety of all those connected with the operation, especially the end-user.

Good Manufacturing Practices (GMP)

Good Manufacturing Practices, or GMPs, are the minimum sanitary and processing requirements issued by the FDA (under section 520 of the Food, Drug and Cosmetic Act) that a company must uphold.

Within the foodservice industry these typically consist of maintaining:

  • A clean kitchen
  • A safe water supply
  • Good personal hygiene of all employees
  • A consistent and thorough employee training system
  • An up-to-date pest control program

Most foodservice industry companies use GMPs to write more specific Standard Operating Procedures (SOPs) and to implement a comprehensive food safety program.


Hazard Analysis Critical Control Point, or HACCP, is a systematic approach to food safety within a facility it focuses on the prevention of biological, physical, and chemical risks by establishing checkpoints at risk-related areas throughout a facility. For example, one might test a fruit processing plantÕs rinsing water at regular intervals to ensure that bacteria is kept below minimum allowance level.

Hollow Core

Hollow core is a broccoli quality problem caused by rapid growth, usually when warm weather follows rain. This cosmetic defect occurs when the outer layers of the stalk grow faster than the middle layers, creating a cavity in the center of the stalk.

Hollow Heart

Hollow heart indicates an open cavity in the center of a potato that turns brown in more severe cases. Its cause is debated: some report it is a physiological disorder caused by not properly rotating fields (planting the same crop in the same lot for multiple growing cycles) others report it is caused by irregular or excessive watering (accelerated by late season rains). Packing sheds use ultrasonic machinery to scan and cull out potatoes with excessive hollow heart. A certain amount of hollow heart is allowed as per USDA Good Delivery Guidelines.

Insect Pressure

Insect pressure is a term indicating the presence of insects in lettuce fields. The number of insects can vary, depending on location and temperatures. Fall is typically the worst time for insect infestations. Many insect populations start in other fields such as cotton and melons when these crops mature, they move to alternative harvesting areas like lettuce.


Product inspections in the field and post-harvest are fundamental to maintaining the integrity of the Markon First Crop, Ready-Set-Serve, and Markon Essentials brands. Markon believes in the adage "trust, but verify," so to supplement our written specifications, inspectors are at work six days a week to approve or reject potential fields for Markon First Crop lettuce, leaf, strawberry, potato and celery items, plus many other vegetable crops. Broccoli, cauliflower, apples, and onions are also inspected. In-house inspectors visit cold rooms three times per week to monitor post-harvest storage temperatures and weights for leaf, lettuce and many vegetable items.

For more information, please watch the "Day In the Life of a Markon Inspector" video.

Integrated Pest Management (IPM)

What is Integrated Pest Management (IPM)?

An IPM system seeks to implement socially responsible and economically feasible methods of reducing agricultural pests and promoting sustainable agriculture for the preservation of the environment. Management options include

  • Cultural: crop rotation
  • Mechanical: cultivating beneficial weeds
  • Biological: releasing beneficial insects or parasites to control other pests
  • Genetic: use of plant disease-resistant varieties
  • Chemical: herbicides, insecticides, fungicides

  • Potential for increased production and improved quality of crops
  • Lower incidences of pesticides in the environment
  • May reduce farming costs

  • Live and/or dead pests in harvested produce
  • Time consuming
  • Inconsistent results

Internal/Tip Burn

Internal burn is when heat and/or rapid growth causes browning on lettuce's inner leaves tip burn is the same condition occurring on the outer tips of leaves. Both problems decrease shelf-life and can lead to breakdown within the lettuce head. They are most prevalent in summer months, when temperatures are extremely high. Both conditions are usually caused when there is rapid growth and plants cannot get sufficient quantities of water to various sections of the head.


A process in which high energy rays pass through packaged food. The process destroys dangerous microbes within and on the surface, including foodborne illnesses such as E. coli 0157:H7, Salmonella, Campylobacter, Shigella, Cyclospora, and Listeria. The process also eliminates pests (such as fruit flies) and slows foods' natural ripening process, extending shelf-life. Nutritional changes are insignificant.

Critics claim that studies of irradiated foods are inconclusive or outdated, and that studies point to the mutation of genes in both animals and humans.

What Methods are Used in the U.S.?

  • Electronic beam, or e-beam technology
    • Most prevalent type used today
    • Used by over 75% of ground beef producers and 50% of poultry processors
    • Purchased by U.S. Postal Service to safeguard mail supply
    • No radioactivity is involved
    • Turned off and on with a switch
    • In use for 15 years
  • X-Ray technology
    • Most used in the irradiation of produce
    • Stronger version of the medical x-ray machine (can penetrate deeper than e-beam, but not as deep as gamma rays)
    • No radioactivity is involved
    • Turned off and on with a switch
    • More effective than e-beams on products that have high water density or inconsistent shapes (such as most fruits and vegetables)
  • Gamma ray radiation
    • In produce industry, most often used on dried herbs and spices
    • Also used in medical supplies, dental equipment, and household products
    • Rays are emitted by radioactive substance (either Cobalt 60 or Cesium 137)
    • Elements give off high-energy photons that can penetrate solids
    • Gamma rays do not make food, or anything else, radioactive
    • In use for over 30 years
    • Does use radioactive materials

Foods Currently Approved for Irradiation

  • Tropical Fruits & Vegetables, Imported (2002, USDA)
  • Meat (1997 FDA, 1999, USDA)
  • Poultry (1990, FDA, 1992, USDA)
  • Herbs and spices (1986, FDA)
  • Fruits and vegetables (1986, FDA)
  • Pork (1986, FDA)
  • White potatoes (1964, FDA)
  • Wheat flour (1963, FDA)

Does Markon Sell Irradiated Produce?

At this time, no Markon branded products are irradiated. In general, the degree of irradiation needed to kill pathogens in produce can damage it (for example, cause lettuces to wilt).

Leaf Miner

Leaf miner problems include the larvae of moths, flies, and beetles that feed on leaves, hence they 'mine' the plant. Evidence of this problem includes spots, discoloration, and pitting. In lettuces, the leaf miner typically feeds on the lower leaves that can be trimmed.

Listeria Monocytogenes

One of the most virulent foodborne pathogens, Listeria monocytogenes is indicated in more than 1,600 illnesses each year in the United States. It is a non-spore forming rod-shaped bacterium that destroys red blood cells and can cause septicemia and meningitis. It’s found in soil, water, and the intestinal tracts of chicken and cows. Because it can live and grow in cold temperatures, it especially dangerous. Listeriosis can be fatal and has even higher death rates than Salmonella.

Listeriosis is usually spread by eating food contaminated by the bacterium. Foods that are often implicated include deli meats, hot dogs, meat spreads, unpasteurized dairy products, smoked seafood, and raw sprouts.

Fever, fatigue, confusion, muscle aches, and gastrointestinal problems including diarrhea.

Young children, pregnant women, the elderly, and immunocompromised persons are most at risk, but given the right conditions, anyone can suffer this illness.


After periods of rain or high humidity, mildew and mold can develop on certain produce items. Products that possess either of these problems are never packed, thus reducing overall supply levels. In some commodities (such as berries and citrus), mold can grow in transit products should be disposed of immediately upon arrival to prevent cross-contamination.


Introduced in June 2011 to replace the Food Pyramid, MyPlate aims to simplify nutritional needs with a colorful plate diagram divided into four portion-size quadrants (fruits, vegetables, grains, and proteins) and one side portion for dairy products. The diagram is accompanied by the United States Food & Drug Administration's advisory tips, including:

  • Balancing Calories
    • Enjoy your food, but eat less
    • Avoid oversized portions
  • Foods to Increase
    • Make half your plate fruits and vegetables
    • Make at least half your grains whole grains
    • Switch to fat-free or low-fat (1%) milk
  • Foods to Increase
    • Compare sodium in foods like soup, bread, and frozen meals--and choose the foods with lower numbers
    • Drink water instead of sugary drinks

See the diagram and additional information at


Norovirus is the most common cause of non-bacterial foodborne illness and gastroenteritis each year, with more than 267 million worldwide cases typically reported each year. Although it usually isn’t dangerous and most people recover within days, as many as 200,000 deaths are reported annually.

It is easily spread from infected people, contaminated foods, water, or by touching contaminated surfaces.

Fever, headache, body aches, loss of taste, dizziness, decrease in urination, stomach pain, nausea, diarrhea, and vomiting.

Anyone can be infected with norovirus, but young children, pregnant women, the elderly, and immunocompromised persons are most at risk. People remain contagious two weeks after recovery.

Organic Produce

The USDA's National Organic Standards went into effect on October 21, 2002. The standards, established by the National Organics Standards Board with the help of thousands of industry and public comments, were written over a period of twelve years. Only foods that meet specific standards can display the national label.

What Are the Labeling Laws? The National Organic Program (NOP) has four classifications of certification

  • 100% Organic
    • Foods must be produced and processed according to specific USDA guidelines
    • Guidelines preclude the use of pesticides, chemical fertilizers, antibiotics, hormones, genetically modified ingredients, and irradiation, among other practices
    • Foods certified to meet these requirements may display the USDA Organic label and/or the statement "100% Organic"
  • Organic
    • Foods must be made with 95% organic ingredients
    • The remaining ingredients may be non-agricultural or not commercially available in organic form
    • Foods certified to meet these guidelines may display the USDA Organic label (but not the statement "100% Organic")
  • Made With Organic Ingredients
    • Foods made with 70-95% organic ingredients can state "Made With Organic Ingredients" on the label (and list up to three organic ingredients), but cannot display the seal
  • Less Than 70% Organic Ingredients
    • Such foods may list organic ingredients in the packaging information panel only (not on the principal display panel)

To view the standards in detail, see The National Organic Program.

  • Provides consistent guidelines across the nation
  • Increases consumer awareness and confidence
  • Predicted to boost sales of organic products
  • May increase organic farming worldwide better for the environment

  • Smaller farmers may not be able to afford the cost of certification
  • May lock smaller grower/suppliers out and relegate organics to bigger businesses
  • May create incentives to import organic ingredients grown in countries with lower costs of production, i.e. Mexico

How Do The New Organic Laws Affect The Foodservice Industry?

To date most foodservice operators are excluded from these regulations, but foodservice establishments may someday be required to document organic suppliers' certifications in order to mention "organic" on menus or in advertising/promotional materials.

For more information about organics and the USDA standards, visit:


Perchlorate is an industrial chemical. In the US it is used as primarily as an ingredient in rocket fuel, and in fireworks and flares. Perchlorate has also been found to occur naturally.

Does food contain perchlorate?

  • There is a potential for perchlorate contamination in food, most likely through the use of contaminated irrigation water, processing water, and via sources used for bottled water (which is a 'food' regulated by US Food & Drug Administration [FDA]). However, FDA does not know the relative contribution of any particular source of perchlorate to that found in foods. Recognizing this potential for perchlorate contamination in food, FDA conducted exploratory surveys in 2004-2005 to investigate the occurrence of perchlorate in certain foods and is using the data collected in these surveys to develop preliminary assessments of human exposure to perchlorate through food FDA has additional investigations planned. The FDA found low levels of perchlorate in milk, bottled water, and lettuce. According to the Environmental Working group, a more recent study by the Centers for Disease Control (CDC) found that Òa significant number of women are at risk of thyroid hormone depression from perchlorate exposure.
  • Perchlorate at high doses (e.g., therapeutic, pharmacologic) can interfere with iodide uptake into the thyroid gland, interfering with thyroid hormone production. Sustained inhibition of iodide uptake can lead to hypothyroidism, which can lead to metabolic problems in adults and abnormal development in utero and in infancy.

Is perchlorate regulated by the government?

  • There is currently no enforceable national drinking water standard for perchlorate either in Canada or in the United States, although various states have implemented guidelines or goals ranging from 1 ppb to 18 ppb for perchlorate in drinking water. In the US, the Environmental Protection Agency (EPA) requires public water systems serving more than 10,000 people (and some smaller systems) to monitor drinking water for the contaminant. As of March 2007, there are several bills under discussion in the US House and Senate requesting that the federal government establish a new drinking-water standard for perchlorate contamination.

  • Dr. Robert E. Brackett, Ph.D., Director of the Center for Food Safety and Applied Nutrition Food and Drug Administration stated, "Consumers should not view the low levels of perchlorate in the foods tested as an indicator of the 'risk' of eating certain foods, particularly when many of the foods are important components of a nutritious and balanced diet. Some of these food items are also important sources of iodine. Until more is known concerning perchlorates occurrence in foods, FDA continues to recommend that consumers eat a balanced diet, choosing a variety of foods that are low in trans fat and saturated fat, and rich in high-fiber grains, fruits, and vegetables."

For more information, visit the FDA, CDC, or Health Canada websites.


  • Prevent stress to reduce the incidence of splitting and Alternaria rot. Healthy, good quality fruit are more resistant to Alternaria rot than stressed or damaged fruits. Stylar-end infections generally occur on orange cultivars with poorly formed navels.
  • Preharvest fungicide applications are usually ineffective.
  • Delay harvest until infected fruit have fallen to prevent inadvertent inclusion of infected fruit in the harvested crop. However, unaffected fruit should be harvested at optimum maturity.
  • Postharvest sprays with imazalil, azoxystrobin, fludioxonil, or mixtures of these may provide partial control.
Common name Amount to use REI‡ PHI‡
(Example trade name) (hours) (days)
Pesticide precautions Protect water Calculate VOCs Protect bees
Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used.
(Graduate A+) 32–64 oz/100 gal water or 250,000 lb fruit NA NA
MODE-OF-ACTION GROUP NAME (NUMBER 1 ): Phenylpyrrole (12) and quinone outside inhibitor (11).
COMMENTS: Use as a dip, drench, flood, or spray.
(Graduate) 16–32 oz/100 gal water or 250,000 lb fruit NA NA
MODE-OF-ACTION GROUP NAME (NUMBER 1 ): Phenylpyrrole (12)
COMMENTS: Use as a dip, drench, flood, or spray.
(FungaFlor 500EC) Label rates NA NA
MODE-OF-ACTION GROUP NAME (NUMBER 1 ): Demethylation inhibitor (3).
* Permit required from county agricultural commissioner for purchase or use.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode-of-action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode-of-action group number for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action group number.
NA Not applicable.

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441

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