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Bacterial leaf streak (BLS) in corn was recently identified in Iowa. Bacterial leaf streak is a disease caused by Xanthomonas vasicola pv. vasculorum. The disease has been found on field corn, seed corn, popcorn, and sweet corn. Iowa State University Extension and Outreach has been working with the USDA, Iowa Department of Agriculture and Land Stewardship (IDALS), the Iowa Crop Improvement Association (ICIA) and surveying several counties in the state.
In the past, corn leaf aphid could be a problem during corn tasseling. This species aggregated around the ear and silks, and sometimes their honeydew production interfered with pollination. But natural enemies and the environment rarely let them persist past July. Therefore, economic thresholds for corn leaf aphid are targeted around VT-R1 and mostly for drought-stressed cornfields. Since 2010, aphids have been colonizing corn later in the summer and are building up to striking levels.
Palmer amaranth was first detected in Iowa in 2013 in Harrison County, and until recently the invasive weed had been found in four additional counties. About a month ago, two landowners (both professional agronomists) detected Palmer amaranth in fields planted in spring 2016 with native seed mixes for conservation purposes. In the time since those July detections, Palmer amaranth has been found in an additional five counties (multiple fields in several of the counties). We think it’s safe to say the calm before the storm has ended.
Information provided by Bob Hartzler, compiled and written by College of Agriculture Life Sciences and Iowa State University Extension and Outreach.
In April 2016, an ICM News article showed a prediction for higher survivorship of overwintering bean leaf beetles in Iowa. Not surprisingly, I have been finding more bean leaf beetles in my research plots and hearing about adults in commercial soybean this summer. Most people have reported minor defoliation from overwintering and first generation adults, but some scouts are wondering about the potential for second generation injury.
