The Decline of Mortality of Cottonwood Clone Stoneville 124 on a Clay Soil

A decline sequence involving multiple factors was proposed as the cause of death and diminished crowns of 12-year-old cottonwood planted on a clay site. Stoneville clone 124, of which the plantation was formed, has proved to be poorly adapted to clay soils. Rates of death and weakened crowns were shown to be related to minor elevation differences within the plantation, the higher, drier areas being the most affected. Finally, several weak pathogens, including Phomopsis macrospora, apparently participated in weakening and ultimately killing the trees. Additional keywords: Populus deltoides, Phomopsis macrospora, twig canker.