Paulownia tomentosa or the Empress tree is a medium sized tree that grows in the United States hardiness zones five through nine. According to the North Carolina State University, the tree grows best in full sun to partial shade conditions and in moist, deep well drained soil, but can tolerate a variety of soil conditions. Empress trees are favorable for growing because they are resistant, but not immune, to many common diseases, insects and pollution.
According to the University of Tennessee Extension, Paulownia is a native subtropical tree used as a cash crop in Japan, but can exhibit hearty growth on Paulownia plantations in the United States. Sunlight is a major concern for Empress Tree growth because they require full sunlight for optimum growth. According to the University of Tennessee Extension, Paulownia grows best in areas where full sunlight is available, typically on the edge of a forest or a growing plantation. Although the Empress Tree is an invasive exotic in the United States, it rarely invades growing areas because of its need for full to partial shade sunlight conditions.
Armillaria Root Rot
Armillaria root rot, caused by the fungal pathogen Armillaria mellea, infects a variety of trees and shrubs, including the Empress Tree. The disease is soil-borne and typically affects weakened trees damaged by poor sunlight conditions, drought and poor soil conditions. According to the University of Illinois Integrated Pest Management, symptoms of an Armillaria root rot infections include leaf drop, premature leaf coloring, stunted growth, yellow to brown foliage, twig and stem dieback and eventually death. However, the disease can infect only certain roots, which causes select dieback rather than tree death. The University of Illinois Integrated Pest Management recommends keeping the Empress tree in good health by promoting full sunlight, removing infected surrounding shrubs or trees and the prevention of mechanical damage. However, fungicide application is not recommended because the disease occurs in the soil and is not easily treated.
When growing the Empress Tree, soil conditions are extremely important for seed reproduction. According to the University of Tennessee, new seeds cannot germinate unless planted in sterile soil. The major concern for soil conditions stems from soil fungi. The seeds are highly susceptible to disease from fungi that are common in most soils. According to the University of Tennessee, the Empress Tree typically does not reproduce or grow in fields in the United States because of fungi levels. However, they do grow well in areas that have had recent construction, burning and road cuts. According to the University of Tennessee, Paulownia rarely grows outside of plantations in the United States because of the extreme soil conditions required for hearty growth.