Cork has been part of human life for most of recorded history and has been used for cork bottle stoppers, footwear and even flooring. Impermeable to liquids and gases, it was prized for its use for gaskets or valves in combustion engines or mechanical applications. Cork is a renewable resource harvested by carefully removing the deeply fissured bark from the Cork Oak tree (Quercus suber)*. The Cork Oak is a large evergreen tree that may stand 60 feet tall with a bulky trunk 4 feet thick to support a wide spread of gnarled, thick branches. It has leathery simple leaves (up to 2” long) that have toothed edges (5-7 each side) and are dark green above and gray underneath. The base of the leaf is flat or slightly heart-shaped. Acorns produced after flowering are oval shaped and ripen in the fruiting year. They are about an inch long, and are held in a scaly cap that encloses over half the acorn.
Early in World War II German submarines disrupted cork shipments from Spain and other Mediterranean countries. Compounding the situation, a fire, said to be one of the few authenticated acts of sabotage in the United States, destroyed Crown Cork and Seal company’s cork stockpile in Baltimore, Maryland.
The late Charles E. McManus was president of the Crown Cork and Seal, the largest user of cork in the nation. McManus declared it was high time that somebody broke the Mediterranean’s corner on the cork market.
With this thought in mind, McManus came to Arizona for a short winter vacation. He was pleasantly surprised to find a cork oak tree thriving on the grounds of the Arizona Biltmore Hotel. Twenty-five other cork trees were found growing in the divergent climates of Douglas, Tucson, Superior, Chandler, Tempe, and Phoenix.
McManus collected specimens of the corky bark and had them tested. Arizona cork, experts agreed, was equal or superior in quality to that imported. Immediately, McManus began a cork tree-planting campaign that would eventually cost him a half-million dollars.
Cork oak acorns were collected. Nurseries, government and commercial growers throughout the southland were asked to sprout the young cork trees. Wherever a climate seemed good, McManus distributed cork seedlings to all takers, free of charge.
In Arizona (about 1946), carloads of the cork seedlings were given away to farmers, to homeowners, to recreation areas, to resorts, to companies and utilities. One railroad car containing 6,000 young trees was emptied in two hours. All together an estimated 100,000 trees were distributed.
Parallel with the planting of cork trees in Arizona’s cultivated areas, McManus hoped to spread cork trees through the forests. Tons of acorns were gathered for this program. Experimental plots were set up in two Arizona forests, generally under the Mogollon Rim.
With McManus’s death in 1946, interest in the program began to fade. Buell Tade, who had acquired the nickname, Corky, because of his work in distributing the trees in Arizona, tried to continue the work. But without the financial leadership of McManus the planting of cork trees was soon stopped. Tade hoped that thousands of the trees would survive and wanted to have a registry for the trees whose cork could be harvested by crews.
Although all of the cork trees planted in the forests are dead due to drought, and perhaps the hard freezes of high elevations, which were too much for the seedlings, dozens survive to this day in urban areas. The Arizona Community Tree Council has designated several as Heritage Trees and recognizes them on their web site at www.aztrees.org.
*Stripping off the cork doesn’t hurt the tree. It just speeds up the production of cork bark. A cork tree is ready for its first harvest when it is about 20 years old. The first harvest is of poor quality, and can only be used for packing material or to make agglomerated cork products. A 40 year old tree is just reaching its full production. Subsequent harvests occur at nine-year intervals, when the cork layer reaches a thickness of 1-2 in. The harvest from a young tree yields about 35 lb of cork, while the yield for an older tree may be 500 lb. Each tree has a productive life of about 150 years.