The fungus phytophthora blight causes damping-off, root rot, stem rot, stem girdling, and fruit rot. Meadow voles may damage woody vegetation by girdling when population density is high. Sometimes the tissue above the canker will die causing girdling of the stem. Rabbits and voles eat the bark, sometimes girdling young trees. Basal girdling and death of seedlings may occur, a symptom known as collar rot. The injection leads to tell-tale girdling at the injection site on grapevine petioles. It kills trees by the girdling action of the larvae. Oriental Bittersweet, Oriental Wisteria, and English Ivy all can damage and kill trees by girdling. Foresters use the practice of girdling to thin forests. Girdling can be used to create standing dead wood, or snags. Girdling is commonly used on grape, avocado, apple, litchi, mango, citrus and other trees. Girdling results in the death of the area above the girdle over time. String girdling Earth is a mathematical puzzle with a counterintuitive solution. Human practices of girdling including forestry, horticulture, and vandalism. One of several ways rabbits damage the environment in Australia is by girdling.