NPIPM:Papaipema nebris (corn)
Authors: Buyung Hadi, Robert J. Wright, Tom Hunt, Keith Jarvi, R. Jeff Whitworth, Holly Davis and J.P. Michaud
Identification
The young larva of common stalk borer (Papaipema nebris) bears distinct white strips at the front and back end of the body separated by a solid black area in the middle of the body. Fully grown larvae are about 1.5-2 inches (3.81-5.08 cm) long and uniformly dirty gray in color.
The adult moth of the common stalk borer is dull-gray or brownish in color with several white spots across the front wings. The moth's wingspan is approximately 1 to 1.25 inches
Life Cycle and Seasonal History
Female common stalk borer moth lays eggs on grasses such as smooth brome or ragweed in late summer or early fall. Sites like fence rows, terraces and waterways are preferred for egg laying. These eggs serve as the overwintering stage. The eggs surviving the winter begin to hatch in the spring. The larvae bore into the grass or broadleaf stems and begin to feed. As the larvae grow larger or if the host plants are mowed or sprayed with herbicides, the larvae may move to adjacent plants to complete their development. Common stalk borer can feed on various hosts including corn, ornamentals, grasses and broadleaf weeds. Corn between 2 and 8-leaf stages are prone to common stalk borer attack. The larvae develop for about 10 weeks before pupation starts in the soil. Adult moths emerge from these pupae in the summer.
Plant Injury and Damage
The larvae of common stalk borer feed through the leaves in the whorl, leaving irregular rows of small holes on the unfurling leaves. The holes on the leaves caused by common stalk borer are larger and more ragged than the ones produced by European corn borer larvae feeding . The leaf feeding alone does not cause economic damage; as larvae tunnel into the stalk plant deformation and stunting may result. Plants attacked at earlier growth stages may be more severely injured; stalk tunneling may cause plant death. One larva of common stalk borer can injure more than one plant if the first plant does not support the larva as it grows. Injuries due common stalk borer larvae are usually limited to plants located on the edges of the field.
Management Approaches
Scouting and Threshold
Check corn plants bordering grassy areas when 1,300-1,400 degree days (41˚F base) have accumulated since January 1. Choose 5 or more of these areas around the field and examine 10 plants per area. Determine the percentage of plants with stalk borer injury on these areas.
Cultural Methods
Any cultural practices that eliminate grassy weeds within the field will reduce the number of egg-laying sites for adult moths. Since stalk borer feeding on younger plants produce heavier damage, early planting may allow corn to escape stalk borer infestation.
In areas with history of common stalk borer, burning areas with grassy weeds on the borders will reduce the pest population. Burning these areas in late winter, before the grass begins to grow may be the best option. At this time all eggs have been laid and the soil will be bare and subject to erosion for the shortest time.
Genetically engineered hybrids
Some BT-corn hybrids (e.g. YieldGard) provide population suppression (not total control) against common stalk borer.
Other Online Resources
Common stalk borer in corn- University of Nebraska
Common stalk borer - Kansas state university
Radcliffe's IPM World Textbook, Maize Insect Pests in North America
