Prevention of Live Oak Wilt

Cause

• Oak wilt is a fungal disease caused by Ceratocystis fagacearum, a pathogen native to the United States. Susceptible hosts include a wide range of oak tree varieties. The disease is among the most destructive oak tree diseases in the eastern regions of the United States, cites the United States Department of Agriculture website. The pathogen kills thousands of oak both in domestic landscapes and in forests.

Damage

• Live oak infected with fungus dies slowly or rapidly depending upon weather conditions and the time at which the infection occurred. Total decline usually occurs in one to six months after infection but can take longer. Early symptoms include yellowing veins that gradually turn brown. Some leaves display yellowing margins or tips. The symptom is referred to as veinal necrosis. The tree starts to defoliate and the crown thins. Overall tree health declines as the tree gradually dies.

Preventive Strategies

• Prevent live oak wilt by minimizing unnecessary damage to the tree. Do not prune trees in spring or early summer but wait until fall and a hard freeze. If you do need to conduct any pruning during susceptible periods, treat all cuts with a wound dressing. Avoid planting trees in poorly drained, heavy clay soil. Remove an infected tree from roots after infection is confirmed. This will keep the disease from spreading to healthy trees. Do not use diseased trees for domestic firewood unless the wood is processed and used up entirely before spring.

Chemical Control

• Use preventive chemicals before infection. These fungicides, injected into the tree, need to be timed precisely as they will not stop the disease from spreading once the pathogen has infected tree. Commonly used products include those containing propiconazole. Because these fungicides are expensive, it is best to consider their use only on high-value oak trees, suggests the United States Department of Agriculture website.