Lawn Academy – Necrotic Ring Spotadmin2022-04-09T00:56:16+00:00

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

Adult


	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.

Pupa


	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.

Larva


	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.

Egg


	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.


	Bean-shaped, off-white colored egg. Approximately 1/16 inch in size.

Larva


	The body is off-white except for the darker reddish head. A fifth-stage larva ranges from 3/16 inch to 1/4 inch.

Pupa


	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.

Adult


	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.

Adult


	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

Larva


	When fully grown they reach 3/4 to 1 inch. Over winter they form in silk-lined tunnels or burrows


	Pupate in late spring (May-June.) Reddish-brown in color, and normally buried in upper thatch

Egg


	Flat oval, and creamy white in color and turn brownish-red as they mature. Laid on upper surface of grass leaf blade

Adult


	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.


	Yellow egg with four short projections on the cap at the head end


	Red body with white stripe behind the wing pads


	White to dark brown in color. Can reach 3/4 to 1 inch in length.

Egg


	Small, white egg about 1/16 to 1/8 inch. Egg is encased in soil particles and turns dark just before hatching.

Larva


	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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