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Emerald Green Arborvitae Disease

Emerald Green Arborvitae are a common hedge tree that is easy to care for and not prone to pests or disease. The tree is susceptible to freezing damage which will cause branches to turn white and die, but it would have to be exposed to extreme cold to cause this problem. The plant is native to the U.S. and is in the family of Cypress or Cupressaceae. It is extremely popular as a hedge since it is healthy in both sun and partial sun and tolerant of a variety of watering and weather conditions.


The color on Emerald Green Arborvitae is an intense green, hence the name, and it is an evergreen conifer. The tree grow upright in a vertical cone, which makes it very pretty as a hedge. The leaves are scale-like, with a darker green on top and the bottoms are a lighter green. Emerald Green Arborvitae is hard in zones 2 through 7. It is also known as Thuja occidentalis 'Smaragd'.


This arborvitae grows about four feet a year and can get up to fourteen feet with a four foot spread. It is easy to prune into size and can even tolerate very close planting. Many arborvitae can grow up to 25 to 40 feet, so this specimen needs to be kept manageable for the home gardener.Pruning should take place in the beginning of the season, before it sends out new growth. It is rarely necessary to shape it much as its growth habit keeps it conical. It makes an attractive border plant, and a good privacy hedge.


All arborvitae are hardy and have few pest and disease problems. Emerald Green Arborvitae is no exception, but it can get a type of fungus that causes blight. Keithia blight is very serious and causes black shotholes in the foliage which will eventually turn brown and fall off. Seiridium blight will cause twig cankers and twig and foliar die back.


Fungicides are effective against blight, but must be applied in the time and amount package instructions indicate. Follow up treatments are usually recommended and it may even be necessary to spray annually for fungus issues. A fungicide high in copper is the best to use. Additionally, take care not to plant the trees too close together. When they are small it is easy to overlook the fact that they will get four feet wide. Plan for this distance when initial installation occurs and the plants will have adequate air to keep fungus from growing well.


Giving the plant adequate air, water and soil requirements are often all that is needed to defeat disease and fungal problems. The arborvitae need to be in sandy to clay loam with moist to average water. Plant them a bit more than four feet away to give a bit of air in between. Fertilize early in the season with an all purpose fertilizer or test the soil so you can see what nutrients might be lacking.

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