Joanne Whalen, Extension IPM Specialist;jwhalen@udel.edu
Field Corn
We are starting to see the first cutworm damage (leaf feeding) in the earliest planted no-till and minimum till corn. In addition to black cutworm, which generally attack later planted corn, a number of other cutworm species can be found in corn fields at planting time including the dingy cutworm, claybacked cutworm and variegated cutworm. Information from the Midwest indicates that the claybacked cutworms can cause economic loss in corn. They overwinter as half-grown larvae in the soil so they can get a “jump” on black cutworms when it comes to cutting each spring. Since they are larger in size, this species can damage very young corn plants. Scouting fields at plant emergence is important, even if at planting materials were used, to catch any potential problems. In addition, a higher rate of an insecticide will be needed to control larger cutworms. As a general guideline, a treatment is recommended if you find 10% leaf feeding or 3% cut plants.
Small Grains
With the continued cool weather, winter grain mite damage has increased in a number of no-till small grain fields this past week. In many cases, damage (which has a silver-gray appearance) has been found but mites are often difficult to detect during the windy weather we have been experiencing. Heavily damaged leaves will have brown leaf tips. In general, this mite will move under the soil surface when conditions are windy. Although there are no thresholds available for winter grain mites, a control may be needed if significant silvering is present and plant growth is being held back from their feeding.More information on identification, sampling and management can be found at the following links:
http://extension.udel.edu/factsheet/winter-grain-mite-management-in-small-grains/
http://entomology.k-state.edu/extension/insect-information/crop-pests/wheat/winter-grain-mite.html
We are just starting to find the first true armyworm moths in our light traps. As a reminder, both overwintering and migratory moth populations are responsible for our infestations. Information from the University of Kentucky is showing low populations in one location and average populations in another area: http://www.uky.edu/Ag/IPMPrinceton/counts/taw/tawgraph.htm. The next few weeks will provide more information on the potential for late armyworm outbreaks in our small grain fields this season.