The sweet corn variety plots at Pinney Purdue provide a good chance to observe sweet corn insects. In late July I observed two caterpillars that surprised me. The first was European Corn Borer (ECB), in the tassel where they are often found (Figures 1 & 2). It was a surprise because I have seen many fewer of these in the sweet corn plots in recent years. I understand from the entomologists that it is due to the widespread use of Bt field corn that has resulted in much lower populations of ECB. The week of Aug. 19 I observed an ECB egg mass on a flag leaf and a young larva on the ear (Figures 3 & 4). The second late July observation was a corn earworm (CEW)–the insect itself is not surprising, but it was in the tassel! (Figures 5-8). I have previously only seen them in ears. The[Read More…]

We have begun our state-wide trapping and monitoring program for corn earworm (Figure 1). The latest trap catch information can be found here. Traps have been placed at each of the eight Purdue Agricultural Centers throughout the state. Trap catches at the reporting farms are already in the double digits. Please refer to E-31 to learn more about corn earworm identification and management. Management and insecticide sprays target the eggs that are laid, preferably on fresh corn silk. If no field corn in the area is silking, which is true for most this year, use a threshold of 1-3 moths per night per pheromone trap. You only need to spray your sweet corn if it has silk present. When field corn begins to silk and green silk is present the threshold increases to 10 moths per night. Eggs are laid individually on developing silk. They hatch within 2-5 days and[Read More…]

We have had major flights of armyworm moths (Figure 1.), as evidenced by pheromone trap catches. Catches have been highest in the northeastern portion of the state. Armyworms prefer grasses but will feed on other crops if necessary. During outbreak years, the infestation usually will start in pastures or other grassy areas. Once the armyworms have consumed most of the available leaf tissue, the larvae will march as a group (hence the name) looking for something else to eat. The next crop consumed may be wheat or early corn. When populations are heavy, the damage can be devastating. Fortunately, these kinds of outbreaks occur quite rarely. The last major outbreak we experienced was in 2001. If you have early-planted sweet corn, it would be wise to watch grassy areas for armyworm damage. If you see evidence of a problem there, watch your sweet corn for any signs of activity. The[Read More…]

I am continuing to catch a small number of corn earworms in my trap. Usually we talk about earworm moths being attracted to silking corn to lay their eggs. However, moths will lay eggs on whorl stage sweet corn and the larvae can cause damage (Figure 1 and 2). The larvae will often feed inside the whorl, similar to European corn borer feeding. This damage is usually not very serious, but growers with very early sweet corn should be aware of the potential.