Soybeans: Bean Leaf Beetle (Certoma trifurcata)

Excerpt from Chapter 3, Field Crop Protection Guide, Order this publication

Table of Contents

1. Description
   • Seed Treatment
     • thiamethoxam – Cruiser 5 FS
   • Foliar Treatment
     • cyhalothrin-lambda – Matador 120 E
     • dimethoate – Cygon 4 E, Lagon 480 EC
2. Related links...

Description

The bean leaf beetle adult is around 5 mm in length (small) with four black spots usually found on the wing covers. Adult beetles can vary in colour but are most often yellow-green, tan or red. A small, black triangle is visible at the base of the wing covers (the prothorax - behind the head). The margins of the wing covers have a black border.

Image 1. Bean leaf beetle adults vary in colour,
but always have a small black triangle visible behind the head.
They may or may not have four spots.

The bean leaf beetle is often confused with the spotted cucumber beetle. A small black triangle is visible at the base of the wing covers (behind the head) of the bean leaf beetle.

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Integrated Pest Management Options

This insect vectors Bean Pod Mottle Virus. See OMAFRA Publication 811, Agronomy Guide for Field Crops, for sampling methods and management options.

Seed Treatment

Seed treatment recommended only for those fields with a history of early season infestation from overwintering adults. Fields in Essex and Kent Counties in particular tend to experience injury to the seedling crop from early infestations of beetles.

Comments
For use in commercial seed treaters only. To reduce early season defoliation.

Foliar Treatment

Rarely do bean leaf beetle populations cause enough defoliation to require an insecticide application in Ontario. Defoliation thresholds during the R1-R5 stage are available in the OMAFRA Publication 811, Agronomy Guide for Field Crops.

Food-grade and seed soybeans may require protection, especially during the later R5 and R6 pod stages to reduce pod disease development caused by beetle feeding. If 10% of pods have feeding damage, insecticide may be necessary. Pay attention to preharvest intervals when spraying during the R6 stage of soybeans.

Comments
Ground application only. For best results, apply during the early morning, before temperatures rise, and during the evening, past the heat of the day. Use 100-200 L water/ha. Maximum of 3 applications/yr. 21 days to harvest. Do not re-enter treated areas until 24 hr of treatment.

Comments
Do not feed or allow livestock to graze treated forage. No more than 3 applications per season. 30 days to harvest.

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Related links...

• Agronomy Guide for Field Crops - Publication 811
  • Soybeans: Bean Leaf Beetle
• Insects
• Soybeans

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