The origins of the lemon (Citrus limon) are unknown, though its history dates back as far as 200 A.D. when the fruit is believed to have been brought from India to southern Italy.
Reports of lemon cultivation appear in both Iraq and Egypt around 700 A.D. as well as in Sicily and China around the same period. Lemons were valued for their medicinal qualities after Arabs introduced them throughout the Mediterranean.
Lemons arrived in the New World in the mid-1700s where they were initially grown in California. Cultivation spread to Florida by 1839, leading to commercial production in both states by 1870.
California leads domestic production, through Mexico is the top producer globally, followed by Argentina and the European Union.
An oval-shaped fruit with a nipple-like bulge at one end, lemons usually have a peel around a quarter-inch thick. Peels are shades of yellow and pocked with oil glands, though some have green, yellow, or white stripes running lengthwise along the fruit. Pulp is pale yellow and acidic with a distinctive sour taste. The fruit is divided into several segments with few or no seeds.
Lemons typically garner the highest price per box of all citrus fruits. Most are used as juice, a garnish, or for cooking, but per capital consumption of fresh lemons continues to climb annually. The highest demand for lemons is in the summer months with the popularity of lemonade and other juice-based drinks.
Types & Varieties
Lemons can be separated into two categories: ‘true’ lemons and ‘rough’ lemons. True lemons are the original fruit thought to originate in India. Rough lemons are similar but less acidic and larger, with a bumpier peel and more seeds.
Other fruits that are sometimes referred to as lemons are Meyer or Ponderosa lemons. Neither are true lemons, but Meyer lemons are often used as a substitute, although they are much less acidic and bear some resemblance to yellowish oranges.
The unusual looking Buddha’s hand lemons are gaining popularity with chefs as a zest.
Popular lemon varieties include Armstrong, Avon, Bearss, Berna, Eureka, Femminello Ovale, Genoa, Harvey, Interdonato, Lisbon, Monachello, Nepali Oblong, Nepali Round, Rosenberger, Santa Teresa, and Villafranca.
Lemon trees grow from 10 to 20 feet in height with sharp thorny branches. Flowers are single or in bunches of two or more, though few pollinated buds will produce fruit. Trees usually achieve full fruit production by their eighth year.
Lemon trees are less sensitive to cold than lime trees, but since they both grow continuously, they are more susceptible to cold damage and less capable of recovery than orange trees.
The best fruit is produced in coastal areas with cool summers, but cold snaps with temperatures below 29°F will kill flowers and new fruit, and just one degree lower can severely damage mature fruit. The 24 to 22°F temperature range will defoliate trees, lower will damage wood.
Many different types of soil are acceptable, which can even grow on sand or silty clay loam, but pH levels should be between 5.5 and 6.5. Rough lemons can be grown from seed, though Meyer lemons are generally grown via rooting cuttings for transplant. Trees should be well spaced and protected from the wind, which will scar both fruit and tree.
Lemons are hand picked at different stages for marketing. California and Arizona producers pick lemons any time after they’ve attained 25% juice content. Some, such as Italian lemons, are picked early and cured. Others are harvested at maturity.
Pests & Diseases
Two major pests of concern are the Caribbean fruit fly and Asian citrus psyllid. The latter causes citrus greening and has wreaked havoc with orange production throughout Florida, and has been found in a few orchards in California. Growers should also look out for purple scale and California red scale, nematodes, and red mites.
Common diseases include citrus canker, phytophthora molds, rust, scab, anthracnose, damping-off, greasy spot, leaf spot, felt fungus, stem-end rot, alternaria rot, various types of root rot and wood rot, as well as the crinkly leaf and exocortis viruses.
Storage & Packaging
Fruit is packed into bins in the field and transported to packinghouses for cleaning, grading, sizing and final packing. Lemons are coated with a fungicide and thin wax layer before curing in storage and later shipping.
Some growers cure loose fruit before grading and another round of curing. Early-picked lemons require about three weeks to attain best color but green lemons may be kept for four months or longer. More mature lemons may need less than a week to cure.
Degreening can be expedited by exposure to ethylene, but care must be taken as this can also promote decay. Packing lemons in thick, high-density polyethylene may minimize decay and allow storage for up to six months. Lemons can generally be kept for up to six months between 54 and 57°F with 90 to 95% relative humidity.
Tree yield varies by cultivar and location and is usually measured in field bins per acre with cartons for shipping. Lemons exported from Florida to Hawaii and Arizona are fumigated with methyl bromide to prevent Caribbean fruit fly infestations.
References: Purdue University, Texas A&M University, UC Davis Postharvest Technology Center, University of California Cooperative Extension.
GRADES & GOOD ARRIVAL
Generally speaking, the percentage of defects shown on a timely government inspection certificate should not exceed the percentage of allowable defects, provided: (1) transportation conditions were normal; (2) the USDA or CFIA inspection was timely; and (3) the entire lot was inspected.
|U.S. Grade Standards||Days Since Shipment||% of Defects Allowed||Optimum Transit Temp. (°F)|
There are no good arrival guidelines for this commodity specific to Canada; U.S. guidelines apply to shipments unless otherwise agreed by contract.
References: DRC, PACA, USDA.
The following defects are unique to lemons only:
• Any amount of mold from a decayed lemon affecting a sound lemon is scored as a defect
• Lemons are prone to internal defect and decline, usually found starting at the stylar end; any amount is scored as a serious damage defect
• Peteca is a deep, sharply defined pitting or sinking of the rind surface and scored as a defect when more than two spots or aggregating more than a quarter-inch in diameter.
Source: Tom Yawman, International Produce Training, www.ipt.us.com.