Fields reaching hard dent may be past the point of a justified insecticide. 7. Scout the ear zone (roughly from two leaves above and one leaf below the ears) for ECB egg masses and ECB or FAW larvae. Don't expect residual to protect the corn from fluid feeders. Journal of Agricultural and Biological Science, 1(2):30-34. Damage Symptoms: Feeds by sucking juices from corn plant; does not inject salivary toxins. The information To monitor aphid populations, examine 100 plants (5 sets of 20) for corn leaf aphids during the whorl stage (3 weeks prior to tassel emergence). Economic threshold (Action threshold): The pest density or level of damage at which a control measure is needed to prevent economic loss. They use piercing-sucking mouthparts to suck sap from the plant. 2 - more than 10 to 20 aphids/whorl. The aphids feed in groups, first appearing in the whorl. As they eat, corn leaf aphids make a sticky gunk called honeydew. Starting in early August, I've been seeing corn aphid populations again. without further permission if published as written and if credit is given to the author, Integrated Crop Management News, 3. corn leaf aphid nymph. Since 2010, aphids have been colonizing corn later in the summer and are building up to striking levels. Corn leaf aphid, Rhopalosiphum maidis Hosts: The corn leaf aphid shows a preference for barley, sorghum, and corn, in that order. Corn leaf aphid is easy to distinguish from the other sorghum aphid species as they have a dark head and legs, a dark green body color, and dark cornicles (see attached image). Corn aphids can colonize the ear and ear leaf. The corn leaf aphid most frequently is found deep in the whorl of the middle leaf of preboot sorghum, but also on the underside of leaves, on stems, or in panicles. The threshold for ECB and armyworms at tassel emergence is 15% infested plants. One important observation I've noticed is that cornfields can have two aphid species - corn leaf aphid and bird cherry oat aphid. The corn leaf aphid can be found on corn, sorghum, wheat and barley in Nebraska. Other aphid species can also be found, including greenbug and English grain aphid, but are not as common in corn this year. Is the field under drought stress? Mold can interfere with photosynthesis and interfere with the grain-filling process. 5. sugarcane aphid. They have spikes rising from the top rear of their abdomen. However, I could find no data to show that corn leaf aphids ever occur in field-wide populations that would justify an insecticide application and as farther indication of this, there is no treatment threshold. What is the corn growth stage? Do you see honeydew and/or sooty mold on the stalk, leaves, or ear? CORN LEAF APHID: Rhopalosiphum maidis, Aphidae. Soybean aphids are tiny, soft-bodied insects that pierce a plant and feed on the sap. From my observations this week, I noticed aggregated colonies at the end rows, but some areas have aphids throughout the field. Note the long black cornicles (tail pipes). A pair of tubes (cornicles) projects from the insect’s rear. The honeydew can become moldy, giving the tops of the plants a black, sooty appearance. This is also a good time to look for corn leaf aphids, record the number of plants with more than 20 aphids. If 50 percent of the plants have at least 100 aphids per plant, or if 3 percent have aphids covering the upper leaves and tassels of the plant, employ a control method. This may be a sign of migration out of the field. 17). Bird cherry oat aphid is green with an orange saddle between the cornicles.Photo by David Cappaert, www.ipmimages.org. This species aggregated around the ear and silks, and sometimes their honeydew production interfered with pollination. 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