If you are like many of the Metro area readers your landscaped has been attacked by the Japanese beetles.

Now what do you do?

Plants are stressed and one of the first things we think of doing is “feed” the plant.  So we reach for our favorite fertilizer and give our plants a good “feeding”.  This is the last thing we want to do.  Revisiting high school biology – plants are autotroph.  This means they make their own food from sunlight, water, and carbon dioxide.  Fertilizers are not plant food and they can actually make the situation worse.  Most fertilizers are high in nitrogen which is responsible for the green growth we see in plants.  When we add nitrogen to a stressed plant we are telling it to grow.  When plants are stressed they are diverting resources to repair and recover and not to growing.  We are also getting close to the time of the year that fertilizing plants will no longer recommend (August 1st).  This is because we want the new growth to harden off before the first potential frost which is usually around October 11th.

Avoid pruning.  Most of the damage has only been done to the foliage and not to the stems or branches.  Waiting until next spring to do any pruning would be best on trees and shrubs.  Most perennials will not need any corrective pruning.

Keep the plants watered.  As of this posting 71% of the state of Nebraska is now in a drought which included the Omaha area.  Also, apply 2″-3″ of wood-chipped mulch around the plants to help conserve moisture.  Keep mulch away from mounding around the crowns/trunk of the plants.

Hopefully we will start to see a decline in their population this week into next.  Until then continue to hand pick and drown them in a bucket of soapy water.

Scott Evans

Scott Evans is a horticulture assistant with Nebraska Extension in Douglas-Sarpy Counties. A certified arborist through International Society of Arboirculture and Nebraska Arborist Association. Scott is also Tree Risk Assessment Qualified through ISA. Scott co-leads the Master Gardener program in Douglas & Sarpy counties. Along with volunteer management he provides his expertise with disease and insect identification, lawn and landscape weed management, plant health, and I.P.M. practices. He also enjoys growing many houseplants ranging from African violets to cacti and succulents. Scott has two Bachelors of Science, one in Biology (emphasis in Botany, Ecology and Environmental Science) and second in Environmental Geology from Northwest Missouri State University. He earned his Master of Agriculture from the University of Nebraska-Lincoln.