Cause Taxus grow best in soil that is well drained and which receives a moderate amount of moisture. In addition, water mold root rot fungi thrive in wet site locations and can cause additional root injury. An insect pest, the black vine weevil, can also injure roots. Refer to Entomology publication E-41 for information on the black vine weevil. Symptoms Dieback symptoms begin with sparse yellowish foliage and poor growth.
Leaves continue to yellow, turn brown, wilt and die.
This is followed by stem desiccation and dieback. Initially only a small portion of the plant may show symptoms but eventually the entire plant is affected. Dieback generally progresses from the top of the plant downward. Several months may elapse from the time the first symptoms appear to the complete dieback and death of the plant. If root damage is caused by excess soil moisture, look for blackened roots with a wet, slimy appearance.