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Thursday - August 31, 2006

From: Helotes, TX
Region: Southwest
Topic: Trees
Title: Possible wilt disease in mountain laurels
Answered by: Joe Marcus

QUESTION:

Three of about 24 of my mature mountain laurels died suddenly, the leaves turned brown almost overnight, scratching the bark revealed no green tissue, the small branches practically cracked when bent, the leaves went from green and healthy to dry and brown in about three to four days, the plant seemed to have just dried up. I do not believe they were over or under irrigated as other healthy mountain laurels remain immediatly adjacent to the dead ones. I detected no caterpillar damage. Any ideas what happened?

ANSWER:

Texas Mountain Laurel, Sophora secundiflora is famously resistant to most pests and diseases; the one major exception being the Genista caterpillar which attacks the leaves. However, the phenomena you described are pretty classic symptoms of a wilt disease. Wilts are usually caused by fungal pathogens invading and clogging vascular tissue in roots or stems of plants, thus the sudden decline of the plant. Species of fungi within the genera Verticillium and Fusarium would be the most likely cause of the disease, but Texas Mountain Laurel is not known to be particularly susceptible to any of them.

There are other possibilities, but without actually examining the plants, it would be difficult to rule any cause either in or out. You should contact your county agricultural extension agent for information on having samples from your dead plants tested to determine the cause of the problem.
 

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