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I have a 14 year-old, quite full, and until recently very healthy hedge of cotoneasters about 1-1/2 feet tall. About a month ago, one section started to become very brown and die. I have watered once weekly in hopes that perhaps this damage was caused by the extra dry, hot summer as they are in full sun. The damage has slowly progressed, and I fear it will eventually spread and cause the complete hedge to die. Is there a condition that plagues these cotoneasters that could have been caused by this summer's extreme heat, and what can I do to save the hedge? Thank you so much. Elena

Answer

I have a 14 year-old, quite full, and until recently very healthy hedge of cotoneasters about 1-1/2 feet tall. About a month ago, one section started to become very brown and die. I have watered once weekly in hopes that perhaps this damage was caused by the extra dry, hot summer as they are in full sun. The damage has slowly progressed, and I fear it will eventually spread and cause the complete hedge to die. Is there a condition that plagues these cotoneasters that could have been caused by this summer's extreme heat, and what can I do to save the hedge? Thank you so much. Elena Hi Elena, Thank you for your photo and question. My best guess, by looking at your photo, is that your shrub has mites. Mites love shrubs that are pruned very tightly so as to not allow sunlight and air circulation through the plant. The dark, moisture-holding, environment provides a perfect home for the mites and other types of insects and diseases. Mites are a part of the arachnid or spider family which also includes ticks and scorpions. They are very small, about the size of the period at the end of a sentence. They live in colonies, mostly on the underside of leaves and feed by penetating the leaf tissue and sucking up the plant fluids. By the time you notice the damage, the plant is infested beyond control. To be sure of what exactly is causing the browning, I would recommend sending a sample of the brown and green stems to the New Haven Agricultural Station for them to analyze.

I cannot give you any advice as far as spraying an insecticide because I do not use them. If you spray an insecticide, in my opinion, you would be wasting your money because the basic problem would still be there...a thick-stemmed shrub creating a perfect home for the insects. Also, an insecticide would probably stress the plant even more. In addition, the lack of rainfall this summer has not helped. Dry soil causes a plant to be stressed and when a plant is stressed it sends out distress signals in the form of electrical impulses or pheromones that insects are attuned to. Even though you watered once a week, it was not enough with the dry summer we experienced.

Shrubs like this need major pruning on a regular basis in order to keep the plant interior open to help deter the mites. If this was my shrub, I would remove it. Good Luck.

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About Linda Lillie

Linda K. Lillie is the President of Sprigs & Twigs, Inc, the premier landscape design and maintenance, tree care, lawn care, stonework, and carpentry service provider in southeastern Connecticut since 1997. She is a graduate of Connecticut College in Botany, a Connecticut Master Gardener and a national award winning landscape designer for her landscape design and landscape installation work.

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