Managing cicadas in nurseries and landscapes

For folks in western parts of the state you may have periodical cicadas in your nursery or landscape.  Of course this will depend on a number of things including the habitat surrounding your nursery.  Areas with a lot of suburban development may have fewer than less disturbed areas.

Cicadas cause damage to trees when they lay eggs in branches.  They use a knife-like

Oviposition scar. Photo: Tim Tigner, Virginia Department of Forestry, Bugwood.org

Oviposition scar. Photo: Tim Tigner, Virginia Department of Forestry, Bugwood.org

ovipositor (egg inserter) to insert eggs into thin tree branches.  This causes slits in the branch that could be 6 inches long or more.  This long scar reduces plant aesthetic value but also weakens branches. Scarred branches usually break and fall to the ground or break and remain hanging in the tree but turn brown.

We have found that imidacloprid reduces oviposition in landscape trees.  (read the full publication) Females detect the insecticide with their ovipositor so treated trees have fewer scars and the scars are much shorter.  Thus branches do not

Flagging branches. Photo: Linda Haugen, USDA Forest Service, Bugwood.org

Flagging branches. Photo: Linda Haugen, USDA Forest Service, Bugwood.org

become as weak so there is less flagging.  This is not to say you should treat every tree with imidacloprid.  Most landscape trees over a few feet tall can withstand losing many branches with no negative effects on health.  Even nursery stock could survive losing branches but may need corrective pruning. Nursery stock can be pruned to remove scarred branches.

Trees that are very valuable could be protected with mesh netting to keep cicadas off (read the full publication). This may apply to specimen trees in landscapes or to particularly expensive nursery trees. Japanese maples may be one species where shape is very important and it would be worth protection of some sort.

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