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Extension > Yard and Garden News > Check Junipers for Disease Damage

Wednesday, April 29, 2015

Check Junipers for Disease Damage

M. Grabowski, UMN Extension

Junipers may be tall, upright, and stately, or low creeping shrubs, but regardless of form, many junipers sport dead tips and brown needles in early spring. To determine the appropriate management strategy, gardeners must take a closer look to ascertain the true cause of the damage.

Juniper with brown dead branch tips.  M. Grabowski, UMN Extension
Kabatina blight - Look for brown tips and dead needles on the end of branches. At the point where brown and green tissue meet, the stem is gray and small raised black spots can be seen with a hand lens. This fungal pathogen infects wounds caused by insect feeding or snow load. Branches that are 1 year old are most commonly affected and symptoms are easily seen in early spring before new growth begins. To manage this disease, clip off diseased branch ends on a cool dry day. Burn or bury infected branches.

Raised black spore producing structures of Kabatina blight. M. Grabowski, UMN Extension
Phomopsis shoot blight - Symptoms are similar to Kabatina shoot blight. Branch tips are brown with dead needles. A section of gray stem tissue is seen where the green and brown tissue meet and raised black spore producing structures occur on dead stems. This fungal pathogen infects young growing shoots and symptoms typically appear in summer after new shoots have grown 4-6 inches. To manage this disease, keep foliage dry by using drip irrigation and making sure lawn sprinklers do not wet the foliage. Do not fertilize junipers with a history of Phomopsis shoot blight. Clip off and burn or bury infected branches. If junipers have been infected with phomopsis shoot blight several years in a row, fungicides can be used to protect young green shoots in spring. Some resistant varieties are available.

Gray stem tissue divides healthy green tissue from brown needles in Phomopsis shoot blight. M.Grabowski, UMN Extension

Rodent damage - Although juniper may not seem like a tasty meal to you or I, voles and rabbits have been known to strip bark off juniper stems during winter. Look for dead needles on one or more branches. Follow this branch back into the canopy and look for scrape marks and removed bark along the branches.

Vole damage to stems resulted in dead needles. M. Grabowski, UMN Extension
Removed bark and teeth marks in the wood clearly indicate vole feeding. M. Grabowski, UMN Extension
Junipers often tolerate tip death and some branch loss. New growth fills in holes left by killed branches. Unfortunately if disease or wildlife damage is severe the juniper may never recover the desired shape. In this case, identify the cause of the problem and search for resistant varieties to use as a replacement plant.

1 comment:

  1. I am really enjoyed reading your article.Thank you very much for sharing such an interesting thing with us.

    ReplyDelete

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