Lawn Academy
Necrotic Ring Spot
Ophiosphaerella Korrae
Necrotic Ring Spot is commonly confused with Brown Patch but it actually has a larger outer ring and larger patch of green in the center.
Management
Use moderate to high amounts of phosphorous, nitrogen and potash. Minimize shade and apply fungicide.
Prevention
Raise mower height, avoid drought stress, and top-dress and aerate turf as needed.
Identification
Causes
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The moth has dark gray and brown wings with white spots at the tip. They have a wingspan of 32 to 40 mm. Average life of about 7 to 21 days. |
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The pupa is reddish brown, and is 14 to 18 mm long and about 4.5 mm wide. This stage last about 8 to 9 days. |
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Fall Armyworms have 6 larval instars. They are smooth and vary in color from light tan or green to black. This stage of development is when most damage is done. |
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Eggs are laid in groups of 100 to 200 with a “fuzzy” appearance. They start out as a pearl green color and darken to a brown color in about 12 hours. The egg stage last for 2 to 3 days. |
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Bean-shaped, off-white colored egg. Approximately 1/16 inch in size. |
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The body is off-white except for the darker reddish head. A fifth-stage larva ranges from 3/16 inch to 1/4 inch. |
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The pupa is initially off-white in color, then darkens to rusty brown and is approximately 5/16 inch in length. It has six legs and wing pads. |
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The adult ranges i color from rusty brown to black and are 1/4 inch to 5/16 inch in length. Their wing covers have a pattern that resembles chains. |
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Referred to as “lawn moths.” 1/2 to 3/5 inches long. When they rest their wings are held flat over the back giving the insect a cylindrical appearance |
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When fully grown they reach 3/4 to 1 inch. Over winter they form in silk-lined tunnels or burrows |
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Pupate in late spring (May-June.) Reddish-brown in color, and normally buried in upper thatch |
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Flat oval, and creamy white in color and turn brownish-red as they mature. Laid on upper surface of grass leaf blade |
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1/6 to 1/5 inch long. Black body with a triangle in the middle of the wings near back with reddish to reddish-yellow legs. |
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Yellow egg with four short projections on the cap at the head end |
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Red body with white stripe behind the wing pads |
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White to dark brown in color. Can reach 3/4 to 1 inch in length. |
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Small, white egg about 1/16 to 1/8 inch. Egg is encased in soil particles and turns dark just before hatching.
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C-shaped body with three legs and brown head.
There are two parallel rows of spines on the last abdominal section.
Fully grown grubs range from 3/4 to 1 7/8 inch
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Hard-shelled beetle 3/4 to 1 inch. Reddish brown or black in color |