Copper has been used for hundreds of years as a fungicide and more recently as a root regulator. Manufacturers or growers often apply a coat of copper-laden latex paint to the interior walls of plastic pots to prevent root growth. Now, copper has been added to a fiber pot prototype created by researchers Robert Berghage, assistant professor of horticulture, David Beattie, professor of horticulture, and Virenda Puri, professor of agricultural engineering. The prototype was developed in collaboration with Henry Molded Products, a Lebanon, Pa., firm. But, in the past, untreated fiber pots didn't last very long.
Roots grow through the pot, water weakens the fiber, and various fungi cause microbial degradation.
But greenhouse growers needed pots with consistent longevity. Growers didn't know if the pots would last a year or fall apart after six weeks. Copper, a plant nutrient found naturally in soil, also acts as a fungicide to stop microbial decay. Because copper affects root growth, roots don't penetrate the paper-based pot and weaken its structure. Woody plants and trees are particularly susceptible to this problem.