Rutgers Cooperative Extension
Kris Holmstrom,
Vegetable IPM Program Associate,
Rutgers NJAES
Sampling Method: 10 samples per field, random area. Sample 5 consecutive plants for a total of 50 plants.
Seedling Stage
| PEST | THRESHOLD | NOTES |
| Flea Beetle | 6+/100 seedlings if no soil insecticide used. | Observe from an upright position so as not to disturb these pests. |
| Fall Armyworm | >/= 12% of plants infested. | Check for ragged injury, droppings, and live fall armyworms. |
Whorl-Tassel Stage
| PEST | THRESHOLD | NOTES |
| European Corn Borer |
>/= 12% of plants infested. | Check leaves for “shot-hole” type feeding signs. Check emerging tassels for live European corn borers. |
| Fall Armyworm | >/= 12% of plants infested. | Check leaves for ragged-hole type feeding signs. Check inside whorl for droppings and larvae. |
| Leaf Rust | Presence | Check for pustules. |
| Northern Corn Leaf Blight |
Presence @ whorl; presence >3 sample sites @ pre-tassel/tassel. | Check for lesions. |
| Sap Beetles | Note: presence may require frequency adjustment to silk spray program. | Check emerging tassels for sap beetles. |
| Corn Leaf Aphid | >/= 12% of plants infested; may require specific insecticide during silk spray program. | Check emerging tassels for aphid. |
Silk Stage
| PEST | THRESHOLD | NOTES |
| Corn Earworm | Apply insecticides at interval prescribed by local blacklight trap catches. | See local blacklight trap information guide spray schedule in the Plant & Pest Advisory Vegetable IPM Updates. |
| Two-spotted Spider Mite | Presence at >1 site. | Check for colonies on underside of leaves. |
| Japanese Beetles | ~10% or more plants with beetles feeding on silks. | Check for presence on emerging silks. |
