February 10, 2016
Source: Alabama A&M University and Auburn University
by Alana Jacobson, Christy Hicks, and Kathy Flanders
Grain sorghum hybrids differ in their resistance to attack by sugarcane aphid. Regardless of variety, it is important to scout each field and apply an insecticide immediately if aphids exceed economic thresholds. Early planting and use of insecticide seed treatments are also recommended. This is explained in a publication by Dr. Calvin Trostle from Texas A&M Agri-Life Extension. Here is one of the conclusions from this paper “Although planting a grain sorghum hybrid with proven SCA [sugarcane aphid]-tolerance/resistance is part of an integrated pest management (IPM) strategy, until we have more information about SCA-tolerant/resistant hybrids, their regional adaptation, and their yield potential it is likely that your timely management of SCA may be more important than which hybrid you plant.”
This post provides some information from tests in Alabama, as well as links to information from other states. Which particular hybrid looked best depended on location and on whether plots were irrigated or not. Growers can use this information on aphid resistance but need to work closely with their seed dealer to pick hybrids that have good local yield potential.
The image below shows a test of sorghum hybrids in Fairhope, Alabama in 2015. Some hybrids were nearly dead, while others were still green and headed out.
In Brewton, Alabama a small plot replicated variety trial was conducted under dryland conditions. In this test aphids were allowed to reach levels far above threshold, and controlled only after their populations peaked. In this test only one hybrid, DeKalb DKS37-07, yielded relatively well under high aphid pressure (44 bu/A). All other hybrids that were tested yielded less than 10 bushels per acre. DeKalb DKS 37-07 also had the fewest aphids per plant at 42 days after planting.
In Headland, Alabama, another small plot replicated variety trial was conducted under irrigation. Again, aphids were not managed until their populations began to decline. Pioneer 83P17 and Mycogen 1G855 had significantly higher yields (>120 bu.A) than DeKalb S54-00, Mycogen 1G741, Pioneer 84P480, Chromatin KS585, Chromatin SP6929, and DeKalb 37-07 (all less than 60 Bu/A). Mycogen 1G588 had intermediate yields (75 Bu/A). Pioneer 83P17, Mycogen 1G855, and Mycogen 1G588 had the fewest aphids per leaf at 45 days after planting.
On-farm strip tests in central Alabama provided additional information on hybrid performance. In these tests, recommended insecticides were applied when sugarcane aphids reached threshold. Thus aphid populations were actively managed in this test. In Talladega County, highest yields were from DeKalb DKS 44-20 (110 Bu/A) and DeKalb DKS 37-07 (97 Bu/A) followed by Pioneer 84P80 (92 Bu/A) and DeKalb S54-00 (90 Bu/A), then Pioneer 83P17 (86 Bu/A) and DeKalb DKS 53-53 (82 Bu/A). In Tallapoosa County, Pioneer 83P17 had the highest yield (89.3 Bu/A), followed by DeKalb DKS 53-67 (82.9 Bu/A) and DeKalb DKS 37-07 (81.8 Bu/A), then by Pioneer 84P80 (73.4 Bu/A) and DeKalb Pulsar (71.2 Bu/A), then by Mycogen 1G741 (59.1 Bu/A), Mycogen 1G588 (59.05 Bu/A) and DeKalb S54-00 (55.6 Bu/A).
Louisiana researchers have summarized the grain sorghum hybrids which have some degree of resistance to sugarcane aphid. The United Sorghum Checkoff Program also provides a list of hybrids that have been identified as having some degree of resistance to sugarcane aphid. Remember, all varieties need to be scouted regularly and insecticides applied when aphid numbers exceed recommended thresholds.
More information on management of sugarcane aphid can be found in these publications:
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