The use of auxin-impregnated toothpicks stimulated adventitious root formation in genotypes of Juglans `Paradox' that had been backcrossed to J. regia. These genotypes were selected as potential rootstocks because of improved tolerance to cherry leaf roll virus and Phytophthora spp. Other auxin applications including quick dips and talc formulations had little or no effect. The use of toothpicks lowered the concentration of IBA necessary for root initiation compared to previously reported results using quick dips. Toothpicks were inserted transversely into holes drilled 1 to 2 cm above the base of cuttings. Callus and roots always formed at the location of the toothpicks rather than at the base of the cutting. Roots were formed using this method in simple layering, hardwood, and semi-hardwood cuttings. Of all the cuttings that rooted, 90% rooted with toothpicks whereas only 10% rooted using a quick dip. This method may have potential for increasing the efficiency of rooting other difficult-to-root plants.
If the inline PDF is not rendering correctly, you can download the PDF file here.