Couplet 24

10/22/2010 5:35:17 AM

10
24a.
Series of dots and faint brown stripes running length of body.

Insect may be:
24b.
Distinct dark-brown stripes running length of body.


Insect may be:


SUGARCANE BORER



RICE STALK BORER





Photo by: Johnny Saichuk

Photo by: Anna Meszaros

SUGARCANE BORER
adults are straw-colored moths with a pattern of black dots in an inverted V-shape on the front wings (3/4 inch long). They lay eggs in clusters of two to 100 on the leaf. In less than one week, larvae emerge, crawl down the leaf, and bore into the plant stem. Larvae feed inside the stem for two to three weeks before chewing an exit hole in the stem and pupating. Adults emerge in about one week.

Facts:
  • Sugarcane borers overwinter as larvae in the stalks of rice and other weedy plants.
  • These larvae pupate in the spring, and adults attack rice when stem diameter is large enough to support larval feeding.
  • Early infestations are noticed when the youngest partially unfurled leaf of the rice plant withers and dies, resulting in a condition called deadheart.
  • Stem feeding during panicle development causes whiteheads.
  • Severe infestations cause stalk breakage and plant lodging.
  • Once larvae enter the stalk pesticides are not effective.

What you should look for:

  • Begin scouting for stem borers at green ring and intensify at early boot stage.
  • Feeding lesions on the inside of the leaf sheath.
  • Frass, to ensure it is not sheath blight damage.

How you can manage sugarcane borers:

  • Destroy crop residues after harvest.
  • Plant early especially in areas with a history of borer infestations.
  • Apply insecticides to coincide with larval emergence so larvae are killed before they enter the rice stalks.

RICE STALK BORER
adult moths have pale white wings tinged with metallic gold (1 inch long). Clusters of eggs are laid on the leaf surface. Larvae emerge in about one week, feed briefly on the inside of the leaf sheath, then bore into the stem. Larvae have two pairs of stripes running the length of the body and a black head capsule. Larvae feed inside the stem for about one month before chewing an exit hole in the stem and pupating in a silken web. The pupal stage lasts one to two weeks.

Facts:
  • The rice stalk borer is a sporadic pest of rice.
  • Injurious infestations usually occur from August through September.
  • Early infestations are noticed when the youngest partially unfurled leaf of the rice plant withers and dies, resulting in a condition called deadheart.
  • Stem feeding during panicle development causes whiteheads.
  • Severe infestations cause stalk breakage and plant lodging.
  • Once larvae enter the stalk pesticides are not effective.

What you should look for:

  • Begin scouting at green ring and intensify as plants get closer or reach early boot stages.
  • Look for feeding lesions on the inside surface of the leaf sheath.
  • Frass to ensure it is stem borer and not sheath blight damage.
  • Look for adults, egg masses or fresh feeding scars on the leaves.

How you can manage rice stalk borers:

  • Destroy crop residues after harvest.
  • Plant early in areas with a history of borer infestations.
  • Apply insecticides to coincide with larval emergence to kill larvae before they enter the rice stalks or during the time they feed on the inside surface of the leaf sheath.


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For more information, please see the Rice section of the Insect Pest Management Guide on the LSU AgCenter's Management Guides webpage.

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