By Kathy Conner Cornell
VCE Southside Master Gardener
I recently read a book called Cork Wars about Crown, Cork and Seal, a cork assembly plant based in Baltimore. Crown, Cork and Seal got their start making bottle caps for beer and soda. I can remember when bottle caps were lined with cork instead of the plastic nowadays. It was interesting to read about the company and events since I knew so many of the places. In 1940, a large fire burned $500,000 worth of baled cork. This was significant because there was a war going on in Europe and the Germans were making shipping treacherous. The cork mostly came from Morocco, Portugal and Spain.
Cork is harvested from the cork oat and used for everyday items like wine corks and bulletin boards.
I knew cork came from a tree but had no clue as to what type of tree. Cork oak, Quercus suber, is a large broadleaf evergreen shade tree native to western Africa and southwestern Europe. It is low maintenance and drought tolerant. The spongy bark of mature trees is used to make wine corks, cork flooring and other items. The cork is harvested when the tree reaches 25-30 years of age and then every 9-11 years for up to 12 times within its lifetime. Cork oak is the national tree of Portugal.
Not knowing how available cork would be, there was a push to grow cork oak in the US. Since the mid-nineteenth century, efforts to grow cork oak trees in commercial quantities in the United States have met with mixed results. Early growers realized that the tree seemed to flourish best in a Mediterranean climate characterized by warm wet winters and hot dry summers similar to that experienced in parts of California. The first serious effort to establish a domestic cork forest industry did not begin until 1939 when Charles E. McManus of the Crown, Cork and Seal Company of Baltimore initiated the McManus Cork Project. Fearing war in Europe would disrupt the supply of cork and lead to shortages and rationing, McManus worked in concert with various government agencies, agriculturalists, and universities to create a new supply of cork oaks here in the United States.
The McManus Cork Project had some short-term success in planting cork oak trees across California. At its height, the McManus Cork Project also mailed out millions of acorns to Americans to plant on the home front. While the effort did not succeed in creating new supplies of trees for the cork industry, the legacy of that effort can be found scattered throughout California and in places where climate and circumstance have allowed individual trees to grow and even thrive.
Although the end of World War II spelled the end for the McManus Cork Project, manufacturers like Armstrong Cork Company in Pittsburgh continued to explore options for growing domestic cork oak trees. Naturally, experts in forestry and dendrology, the scientific study of trees, were consulted. One such expert, Bishop Franklin Grant, a professor of forestry at the University of Georgia from 1929 until 1965, attended at least one meeting in Lancaster, PA. Grant was obviously there to lend his expertise to some question of forestry, most likely having to do in some way with the practicality of growing domestic cork oak trees in this country. The bottom line concluded that growing cork in the United States is impractical.
In its native habitat, the cork oak supports a wide range of wildlife including many endangered species of birds and felines and the acorns are a high-value food source for mammals. Cork oak trees support a wide variety of Lepidoptera, the order of butterflies and moths. The narrow acorns are 1-1/2” long with shaggy caps and are relished by deer and squirrels.
The amazing thing about cork oak, is that using cork is a totally sustainable practice because using the bark every 9 to 11 years doesn’t kill the tree and the bark regrows. Nowadays the cork may be used for flotation, shoe insoles, gaskets, and bulletin boards. It is used in my Birkenstocks which allows the cork to mold into the shape of the foot. With wine going to synthetic corks, twist tops and bag wines, there is concern that the large cork forests will face their demise. Wildlife including lynx, red deer and pigs would lose their homes, and in Portugal alone more than 60,000 people might lose their jobs.
There is over 5.4 million acres of these native trees in Europe and North Africa, with Portugal having over 1.8 million acres, or 23% of their forest in cork oak. So, as Paul Harvey would have said, now you know the rest of the story of bottling wine in the old days.