Weeping willow trees are a tall ornamental tree used in conservation and landscaping. These trees are prone to a variety of diseases affecting many parts of the tree. One of the more common diseases is root disease. Root disease can take on different forms, depending on the pathogen causing the infection. Similar effects, treatments and means of entry can be found for each type of root disease.
Root disease of weeping willow trees is an infection of either a fungal or bacterial pathogen. The infection enters the tree through displaced soil or open wounds around the tree. Root rot deprives nutrients and moisture to the tree, starting at the uppermost canopy and working back toward the base, effectively drying out the tree.
Overall symptoms include discoloration of the bark and leaves starting at the upper canopy. There are different signs of root disease depending on the infection. Fungal infection is evident when brown, oddly shaped spots start to form on leaf surfaces; when the brown spots turn green, the spores are beginning to spread. Bacterial infection is evident when cankers or tumors are found on the bark. Dark, sunken sections will appear randomly where the bacteria entered the tree; this discoloration will spread as the bacteria spreads.
Two types of fungus and one form of bacteria can cause root disease in weeping willow trees. Both cytospora canker and Fusicladium saliciperdum are fungal pathogens found to cause root disease. Crown gall is the bacterial pathogen that can cause root disease.
Root disease can cause severe impairment to the growth of weeping willow trees and can kill the tree. Defoliation and stunting of the tree is common. If the root system becomes too rotted, the roots will loose their grip in the soil, causing the tree to become unstable and collapse from its own weight. The fungal type of root disease can remain in the soil long after the tree has died and been removed, thereby keeping the soil unusable.
The best treatment to keep weeping willow root disease from spreading is pruning of affected areas; removal of dead leaves, branches and twigs should be done immediately. Cut the branches cleanly and allow the cut areas to dry naturally. The dead material should be destroyed. If a tree has died or become too infected, it should be removed and destroyed to avoid infecting other trees in the area.