Protecting cellulosic materials in soil contact poses a formidable challenge. Many soil inhabiting bacteria and fungi that cannot degrade wood can nevertheless rapidly depolymerize cellulose once its protective lignin matrix is removed. As a result, cellulose based materials are rarely used in direct contact with soil. One exception, however, is the use of cellulose string to support climbing vines in agricultural applications such as hop growing. In these instances, the ground contact portion of the string is treated with a fungicide, while the remainder is left untreated. In theory, the string retains adequate strength for the season, and decomposes once the crop is harvested. Typically, copper naphthenate and oxine copper have been used as fungicides. Recently, however, early failures of strings dipped in 3% copper naphthenate have been observed. In this report, we describe trials that evaluate the efficacy of selected fungicide/water repellent combinations on cellulosic string. Water repellents improved the efficacy of some biocides. Further trials are underway to evaluate combinations of biocides.

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