The Iowa Soybean Association has supported three research projects that address issues of evolved herbicide resistances in soybean production. Two of projects have been combined for funding at the request of the Iowa Soybean Association.

The F1 half-sib lines established in 2013 were crossed in the field during 2014 to create F2 full-sib lines to evaluate for HPPD heritability (90 half-sib F1 populations) and putative hybridization of waterhemp and Palmer amaranth (85 half-sib F1 lines). Seeds from each of the female plants were collected and processed. All F1 lines were selfed and replicated three times in the field in 2014 resulting 498 crosses of the 166 separate half-sib lines. All female plants have been harvested and seed processing is underway. Morphological measurements of reproductive structures for the putative hybridization project are being collected. Greenhouse screens for the assessment of HPPD resistance (HPPD heritability study) and atrazine resistance (hybridization study) will begin as soon as the seeds have after-ripened and can germinate.

The third project, “Assessment of glyphosate- and other herbicide-resistant weeds in Iowa: a directed educational opportunity” is still ongoing despite the fact that support from the ISA has terminated. Regardless, the evaluations of waterhemp, giant ragweed and marestail/horseweed populations collected in 2012 and 2013 are ongoing. Data will be made available upon completion of the project.