Node-injury scale to evaluate root injury by corn rootworms (Coleoptera: Chrysomelidae)

Area of Science:

• Agricultural Entomology
• Crop Science
• Plant Pathology

Background:

• Corn rootworm larval feeding significantly reduces grain yield and impacts plant health.
• Current root damage rating scales (1-6 and 1-9) lack linear quantification of injury.
• Existing scales provide qualitative, not quantitative, assessments of root damage.

Purpose of the Study:

• To develop and describe a novel node-injury scale for quantifying corn rootworm larval damage.
• To establish a linear and intuitive relationship between the node-injury scale and actual root injury.
• To determine the minimum node-injury score causing economic damage under various environmental stresses.

Main Methods:

• Development of the node-injury scale based on the proportion of nodal roots with feeding injury.
• Description of sampling considerations for accurate scale application.
• Analysis to identify the economic injury level for the node-injury scale.

Main Results:

• The node-injury scale provides a linear and intuitive quantification of corn rootworm larval root injury.
• The scale allows for more accurate assessment of damage compared to historical scales.
• The study suggests a minimum node-injury score threshold for economic damage.

Conclusions:

• The node-injury scale offers a significant improvement for quantifying corn rootworm damage.
• Accurate quantification aids in evaluating control tactics and understanding yield loss.
• The scale is a valuable tool for researchers and pest management professionals.