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Keithia Thujina Needle Blight


Keithia Thujina Needle Blight

Usually appear in

Spring to Autumn.

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Caused By:-     The Fungus Didymascella thujina(Keithia thujina)


Spores of Didymascella thujina on juniper needles
Didymascella thujina is an ascomycete fungi from the family of Hemiphacidiaceae, which causes Cedar leaf blight (or Keithia Thujina needle blight disease, after the original genus name) in several cedar(Thuja) species. The disease is indigenous to North America, but today is also found in Europe Cedar leaf blight spreads mainlyly by airborne ascospores in humid conditions and can affect large areas, though it is rarely lethally trees older than 4 or 5 years of age. Therefore this leaf blight is of greater concern in nurseries, where conditions are ideal its growth and spread. Symptoms appear as white spots that occur on the upper side of leaves, usually in spring. Over the course of the summer, leaves will turn reddish-brown, and looking like natural leaf death. Later however, the leaves develop black spots as the fungus produces its ascospores. Later the ascospores are released, and the leaves will fall off. Spores will overwinter on uninfected green leaves, and begin their life cycle the following spring.
Picture from Wikimedia Commons.


Control of the disease can be effective with certain fungicides and there are some hybrids that can resist this disease. Keeping plantings well spaced out will help avoid this disease as the disease levels are highest in dense stands where humidity levels are high.

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