True Armyworm Found
Figure 1. Larger true armyworm larvae. Larvae usually feed at night but can occasionally be found in the whorl of corn plants or on the head of wheat during the day, especially on overcast days. Pay attention to the edge of fields near grassy weeds and in particular those fields where corn and wheat are planted beside on another. Corn fields having a rye cover crop are also at risk. Keep checking back every two to three days, as armyworms can take out an entire field in a matter of days. Since armyworms do not feed on the growing point of the plant, corn can recover from moderate feeding. If however you find 2 or more larvae per seedling plant and see at least 10% feeding injury, especially in seed corn, a foliar spray may be warranted. Once the crop is past the whorl stage, it takes approximately 50% of the plants to have feeding damage before control is necessary. It is the wheat crop however that is at risk. If you find four unparasitized larvae per square foot of crop, a spray may be warranted. Keep an eye out for head clipping. If it starts happening, a spray is warranted. Matador is now registered for armyworm control in wheat, barley, oats and corn. A full list of recommended products are available in the table provided. Spraying the field boundaries where the larvae are migrating from might be sufficient. Larger larvae are difficult to control. Control products are only effective on larvae that are smaller than 4 cm (1½ inch). Also, once the larvae are larger than this, they have almost finished feeding and most of the damage is done.
Table 1. Recommended products
for armyworm in wheat.
For more information: Toll Free: 1-877-424-1300 Local: (519) 826-4047 E-mail: ag.info.omafra@ontario.ca
| ||||||||||||||||||||||
