soils, especially those of limestone origin. Butternut's range includes the rocky soils of New England where black walnut is largely absent. Butternut is found most frequently in coves, on stream benches and terraces, on slopes, in the talus of rock ledges, and on other sites with good drainage. It is found up to an elevation of in the Virginias – much higher altitudes than black walnut. The nuts are eaten by wildlife. Associated forest cover Butternut is found with many other tree species in several hardwood types in the mixed mesophytic forest. It is an associated species in the following four northern and central forest cover types: sugar maple–basswood, yellow poplar–white oak–northern red oak, beech–sugar maple, and river birch–sycamore. Commonly associated trees include basswood (Tilia spp.), black cherry (Prunus serotina), beech (Fagus grandifolia), black walnut (Juglans nigra), elm (Ulmus spp.), hemlock (Tsuga canadensis), hickory (Carya spp.), oak (Quercus spp.), red maple (Acer rubrum), sugar maple (Acer saccharum), yellow poplar (Liriodendron tulipifera), white ash (Fraxinus americana), and yellow birch (Betula alleghaniensis). In the northeast part of its range, it is often found with sweet birch (Betula lenta) and in the northern part of its range it is occasionally found with white pine (Pinus strobus). Forest stands seldom contain more than an occasional butternut tree, although in local areas, it may be abundant. In the past, West Virginia, Wisconsin, Indiana, and Tennessee have been the leading producers of butternut timber. Canopy competition Although young trees may withstand competition from the side, butternut does not survive under shade from above. It must be in the overstory to thrive. Therefore, it is classed as intolerant of shade and competition. Diseases Butternut canker The most serious disease of J. cinerea is butternut decline or butternut canker. In the past, the causal organism of this disease was thought to be a fungus, Melanconis juglandis. Now this fungus has been associated with secondary infections and the primary causal organism of the disease has been identified as another species of fungus, Sirococcus clavigignenti-juglandacearum. The fungus is spread by wide-ranging vectors, so isolation of a tree offers no protection. Butternut canker first entered the United States around the beginning of the 20th century, when it arrived on imported nursery stock of Japanese walnut. Symptoms of the disease include dying branches and stems. Initially, cankers develop on branches in the lower crown. Spores developing on these dying branches are spread