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Pests & Diseases
Pests to watch out for include aphids, armyworms, beetles, crickets, cabbage loopers, cutworms, leafminers, leafhoppers, thrips, whiteflies, and wireworms.

Tipburn can be caused by several factors, including variety, soil conditions, and temperature fluctuations. Leaf margins can become damaged and susceptible to decay.

Pink rib is prevalent in over-mature lettuce and warm temperatures in storage. Ribs will take on a pink hue.

Brown stain, as its name suggests, presents with yellow- or reddish-brown spots and stains on ribs and may expand and darken in time.

Soft rot is caused by bacteria and results in a translucent, slimy breakdown of infected tissue. Trimming outer leaves, rapid cooling, and low temperatures can reduce development and spread.

Other disorders and diseases of concern include big vein, botrytis grey mold, bottom rot, downy mildew, leaf drop, mosaic virus, and powdery mildew.

Storage & Packaging
Harvest is labor intensive and lettuce is either packed ‘naked’ or wrapped or bagged. Rib breakage can occur during harvest and packing, resulting in browning and higher susceptibility to decay. If product is harvested early in the morning, when temperatures are lowest, it is more vulnerable to rib damage.

A steady temperature of 32°F with 95% relative humidity will optimize shelf life for up to 3 weeks. Romaine can tolerate slightly higher temperatures during transit and handling, lacking other complications (such as ethylene gas).

Romaine is sensitive to ethylene and damage can appear as discolored spots. These are generally larger and less defined than russet spotting on iceberg lettuce. Variety can dictate susceptibility. Common containers are bushels or cartons holding about two dozen heads.

References: Purdue University, University of Arizona Cooperative Extension, University of California Vegetable Research & Information Center, University of Kentucky Cooperative Extension, USDA.


There is only one grade for romaine lettuce, U.S. No. 1, and there are no grade standards for Canada.

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)
10-5-2 5

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.

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This information is for your personal, noncommercial use only.