Saturday, Sep 22, 2018
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Keep eyes out for aggressors


    Amy Stone, an educator with the Ohio State Extension – Lucas County, Agriculture and Natural Resources.

    The Blade/Lori King
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    A series of Oak trees damaged by gypsy moth caterpillars are only growing slight foliage this season.

    The Blade/Katie Rausch
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Amy Stone, an educator with the Ohio State Extension – Lucas County, Agriculture and Natural Resources.

The Blade/Lori King
Enlarge | Buy This Image

Everyone has likely heard, “tis the season.” While that phrase might remind you of the snow, cold temperatures, and winter holidays, gardeners might now think of seasonal pests in the garden and landscape.

It was the beautiful side of horticulture that drew me to choose a career among plants. I enjoy the challenges of identifying plant pests. What is this bug? Can you name this plant? What caused the leaf spots? Answering these mysteries can make a gardener become a garden detective.

A detective not only solves mysteries, but determines what actions, if any, are needed to manage the situation. Recently, there have been some regulars that I have either observed, received calls or emails, or have been sent samples to diagnose. Here are just a few:

Maple anthracnose

Are you seeing blackening leaves on your maples? If you answered yes, know that you are not alone. These irregular shaped spots usually “hug” the leaf margins and are found between the leaf veins. If the disease is severe, leaves may crinkle up and even fall. While the damage may appear severe, don’t panic.

Controls are usually not recommended. Healthy trees can withstand the infections and often with early season anthracnose, the tree will send out a second flush of leaves that are usually anthracnose-free. For additional information on maple anthracnose, check out this Extension fact sheet:

Japanese knotweed

While I could have picked numerous weeds to highlight this week, Japanese knotweed is one that people have asked about. This non-native invasive is very aggressive and can be difficult to eliminate.

The plant dies back to the ground each year, can grow up to 10 feet tall, and its spread can be even more impressive — or unimpressive depending upon your view. The stems are hollow and are red in the spring as they emerge.

The leaves are arranged in an alternate pattern, are wider at the base, and the tip comes to a point. The flowers are white.

Controls include constant cutting the foliage back, digging it out, chemical treatments, or a combination of the above.

For more information about this weed, check out the Ohio Invasive Plant Council Fact Sheet at:

Gypsy moth

Gypsy moth is a non-native caterpillar that feeds on more than 300 trees and shrubs, but oak trees are definitely a favorite.

The caterpillars have pairs of red and blue raised spots and are slightly hairy. In high numbers, they can totally defoliate entire trees no matter their size. In addition to being a plant pest, they are also problematic when people can’t enjoy the outdoors. Caterpillar feeding equals frass, aka bug poop, falling from above wherever they are feasting.

Quest to suppress

This spring, areas in Swanton, Fremont, and Tiffin were treated for gypsy moth as part of the Ohio Department of Agriculture’s Gypsy Moth Suppression Program.

Homeowners noticing the caterpillars should alert ODA or if in Lucas County contact the Extension office. There are requirements for the cost-sharing program including a minimum of 50 acres, a percentage of tree cover, and plants that insect prefers. The next program won’t occur until the spring of 2019, with a Sept. 1 application deadline. Residents can also choose to have their trees treated by an arborist this season. Biocontrols like the gypsy moth fungus may also help.

While you are in the garden be on the lookout for the other side of horticulture. If you find something you aren’t familiar with know there are resources to help. I would love to help diagnosis those plant problems and might even highlight your plant experience in a future column.

Amy Stone is an extension educator with the Ohio State Extension – Lucas County, Agriculture and Natural Resources. Contact her at:

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