Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2014
Publication Date: 4/8/2015
Citation: Harris-Shultz, K.R., Ni, X., Anderson, W.F., Knoll, J.E. 2015. Evaluation of whorl damage by fall armyworm (Lepidoptera:Noctuidae) on field and greenhouse grown sweet sorghum plants. Journal of Entomological Science. 50(1):14-27.
Interpretive Summary: The fall armyworm is found throughout the United States and is an economically important pest of sorghum. Resistance to fall armyworm in sweet sorghum has not been extensively studied. A collection of sweet sorghums (116) were evaluated for natural fall armyworm damage in two field studies. A wide range of response to fall armyworm feeding exists in this collection. Accessions with the highest and lowest field fall armyworm damage were evaluated in a greenhouse trial. At 7 days post infestation, most sorghum accession has significantly higher fall armyworm damage than resistant control MP708. At 14 days after infestation, all sorghum accessions were as resistant as the resistant control MP708. This suggests that the sorghum lines at 14 d have induced resistance in the growing whorl. In conclusion, this study identifies sweet sorghum accessions that are resistant to fall armyworm damage and can be used by sorghum producers in areas where fall armyworm damage is extensive.
Technical Abstract: The fall armyworm [Spodoptera frugiperda (Lepidoptera: Noctuidae)] is an economically important pest of sorghum [Sorghum bicolor (L) Moench]. However, resistance to fall armyworm in sweet sorghum has not been extensively studied. A collection of primarily sweet sorghum accessions were evaluated in the field for natural fall armyworm infestation. Fall armyworm damage ranged from 1.88 ± 0.35 to 4.75 ± 0.37 suggesting that a wide range of response to fall armyworm feeding exists in this collection. Based on the results of field data from two planting dates, accessions with the highest and lowest fall armyworm damage ratings were selected for greenhouse evaluations. At 7 d after infestation, the sorghum accessions, excluding BTx623 and PI 147573, had significantly higher fall armyworm damage than resistant control MP708. Furthermore at 7d after the infestation, genotypes PI 147573 was the most resistant, whereas genotypes 13, 22, ‘GT-IR8’, and ‘GT-IR6’ were the most susceptible to fall armyworm feeding. For the damage ratings at 14 d after the infestation, sorghum entry 13 had significantly higher fall armyworm damage than GT-IR7 and PI 17548. At 14 d after infestation, all nine sorghum accessions were as resistant as the MP708 resistant control and had significantly less damage than the susceptible control AB24E. This data suggests that the sorghum lines at 14 d have induced resistance in the growing whorl.