European corn borer moths emerging in northeastern Colorado
By Assefa Gebre-Amlak
CSU Extension Specialist
Presence of first-generation European corn borer moths in corn fields were detected with help of pheromone traps in different locations in northeastern Colorado.
First-generation moths prefer taller and early planted fields for laying eggs. If producers have non-Bt early planted corn fields, they should be scouted the next two to three weeks for larval infestations.
To determine infestation levels and make management decisions, 50 plants in four to five locations in a corn field should be checked for leaf infestations. Larval damage is noticed as feeding scars and shot holes in plant leaves. Chemical control of first-generation corn borer is justified when 25 percent of the plants in the sample show feeding damage and show presence of larvae. Chemical control of the pest must be applied before the feeding larvae bore into the stalks.
More detailed management information including effective products, rates of application and others can be checked in the High Plains IPM Guide: www.highplainsIPM.org. Trap counts from different locations are found at the Northeastern Colorado Pest Management website: www.nocopestalert.org.
Another pest that needs to be monitored in corn at the moment is the Banks grass mite. Rapid increase in infestations and population buildup of these minute arthropods is influenced by hot and dry conditions.
Webbing and discoloration of leaves are often the first signs of BGM infestation. Banks grass mites are abundant on the lower third of the plant and move up on the plant.
Treatment for BGM management is justified when there is a visible damage in the lower third of the plant and small colonies present in the middle 3rd of the plant before hard dough stage. For effective products check the High Plains IPM Guide at www.highplainsIPM.org.