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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Publications at this Location » Publication #326345

Research Project: Genetic Improvement of Maize and Sorghum for Resistance to Biotic Stress

Location: Crop Genetics and Breeding Research

Title: Grain sorghum hybrid resistance to insect and bird damage - 2015

Author
item Ni, Xinzhi
item Harris-shultz, Karen
item Knoll, Joseph - Joe
item Toews, Michael - University Of Georgia
item Buntin, G - University Of Georgia

Submitted to: Agricultural Experiment Station Publication
Publication Type: Experiment Station
Publication Acceptance Date: 12/1/2015
Publication Date: 12/1/2015
Citation: Ni, X., Harris-Shultz, K.R., Knoll, J.E., Toews, M.D., Buntin, G.D. 2015. Grain sorghum hybrid resistance to insect and bird damage - 2015. In: J.D. Gassett, D.D. Dunn, H. Jordan, Jr., and J.L. Day (eds.), Georgia 2015 Soybean, Sorghum Grain and Silage and Summer Annual Forages Performance Tests - Annual Publication 103-7, pp. 63-65. December 2015. Available: http//www.swvt.uga.edu/2015/sysr15/AP103-7-srGrain-web.pdf (Experiment Station).

Interpretive Summary: not required

Technical Abstract: A total of 26 grain sorghum hybrids (24 commercial grain sorghum hybrids and a pair of sugarcane aphid resistant and susceptible controls) were evaluated for resistance to insect and bird damage in Tifton, Georgia. A total of 10 insect pests were observed. The insect pests in order of importance are: sugarcane aphid, sorghum webworm, sorghum midge, leaf-footed bug, fall armyworm, corn earworm, corn leaf aphid, stink bugs (southern green and brown stink bugs), and chinch bug. In comparison with sugarcane aphid population and its damage, sorghum webworm, midge and bird damage were relatively low in 2015. Due to low populations, fall armyworm, corn earworm, leaf-footed bug, stink bug, and chinch bug damage data were not included in this report. In addition, diseases were of minimal importance in this trial. Heavy sugarcane aphid infestation at the seedling stage was observed in the experimental plots that were planted on June 5, 2015. In fact, sugarcane aphid infestation, which generally occurred between mid-July and early August, was so severe that it halted normal plant development before flowering resulting in that 14 hybrids did not produce panicles. Missing values in “Days to Anthesis” column of Table 1 indicate the hybrids did not produce panicles from main stems. Any panicles from delayed tillers after aphid population crash were not included in the table. Most of these hybrids aborted their panicle development at the flag leaf (or boot) stage. Results from 2015 showed that sugarcane aphid infestation at the seedling stage is much more serious than the post flowering infestation observed in late August 2014. Although sugarcane aphid damage was rated multiple times throughout the season, the rating recorded on August 7, 2015 was used for this report, because this rating best characterized the aphid damage (leaf discoloration) before regrowth of green tillers appeared. Sugarcane aphid damage was ranked using the following scale: Very Good (VG) = no visible aphid damage, and only a few aphids colonizing the leaves; Good (G) = a lot of aphids without damage symptoms, but with honeydew visible on the surface of lower leaves; Fair (F) = high aphid population with lower leaves covered with honeydew, sooty mold and aphid exuviae (or whitish-caste skins); and Poor (P) = sorghum plants were killed by aphid infestation, or did not produce viable panicles on main stems. Sorghum webworm, midge, and bird damage were ranked before harvest on September 11, 2015. Both sorghum webworm and midge damage were assessed in combination with grain loss according to the following rating scale: Very Good (VG) = 0-15% empty glumes on any of the sorghum panicles in an experimental plot; Good (G) = a few empty glumes (16-30%) observed on a panicle; Fair (F) = 31-75% empty glumes on a sorghum panicle; and Poor (P) = majority of sorghum panicles with more than three quarters (> 75%) empty glumes. Finally, bird feeding damage on developing kernels was determined by presence of partial kernels on panicles, and evidence of splattering of broken developing kernels falling on top leaves of a plant. Bird damage was rated with the following scale: Very Good (VG) = less than 10% grain loss; Good (G) = 11-25% loss; Fair (F) = 26-50% loss; and Poor (P) = > 50% loss of grains per panicle. The heavy sugarcane aphid infestation occurred at the seedling stage for a period of approximately 4 weeks before flowering, and then the aphid population crashed in early August, 2015. Although relatively short in duration, the infestation with high aphid population permanently stopped main stem growth of 14 sorghum hybrids. Only four of the 26 hybrids consistently produced normal panicles from all four replications of the trial. These four hybrids were ‘GW 9417’ from Gayland Ward, ‘GX13231’ from Dyna-Gro, ‘AG1203’ from Alta Seeds, and an aphid resistant control