European corn borer were caught at most locations this week, with Penn Yan and Farmington again seeing the highest trap catches.  Robert Hadad, with the Cornell Vegetable Program reports finding ECB egg masses and small larvae in tassel-emergence stage fields.  These more advanced fields tend to have the highest pressure as egg-laying female moths are most attracted to the larger corn.  Two to three insecticide applications during the moth flight should prevent larvae from entering developing ears.

Corn earworm and fall armyworm were caught at only one location, Waterport, this week.

Special note: common (true) armyworm is being found in very high numbers in some western and central NY locations, with at least on field corn planting suffering a total loss.  From the Field Crops IPM Weekly Pest Report:

It is important to detect armyworm areas early, while larvae are still small, since large larvae do most of the feeding and quickly destroy whole stands of corn, grasses and small grains. Because armyworm feeds at night look for chewed leaves, cut stems, lodged plants, pellet-like frass on the ground, and larvae hidden under plant canopy and surface residue. You will need to be aware that armyworms can move from field to field every quickly. If there are sufficient numbers and damage is present, an insecticide could be justified. Larger armyworm larvae, greater than 1 inch long, are much more difficult to control. These large larvae are more tolerant of insecticides, reducing the effectiveness and economic viability of this option. Note that true armyworms are a different insect species than fall armyworm

True armyworm larvae appear smooth cylindrical pale green too brownish when they are still small. Mature larvae are smooth and marked with two orange, white-bordered strips on each side. True armyworm ranges in size from 1/8 inch to 1 .5 inches long.  Fields near wheat or rye are most at risk.

In Ontario, a threshold of 10% damaged plants is being recommended in seedling stage sweet corn, and 50% damaged plants in mid-whorl stage.  Better get out there and scout!

Identification Resources:

Armyworm as a pest of Field Corn: http://ento.psu.edu/extension/factsheets/armyworm

Armyworm on Wheat: http://ohioline.osu.edu/ent-fact/pdf/0036.pdf

Common  (True)  Armyworm: http://www.omafra.gov.on.ca/IPM/english/sweet-corn/insects/common-armyworm.html

-Thanks to Keith Waldron and Ken Wise, NYS Field Crops IPM Program

Trap catches for the week of 5/30-6/5/12