by Dr. Calvin Trostle, Extension Agronomy, Lubbock, (806) 746-6101, ctrostle@ag.tamu.edu

In 2016 Texas grain sorghum producers will find more information from seed companies and other sources about grain sorghum hybrids that may offer potentially increased—or better documented—tolerance/resistance to sugarcane aphid (SCA). I provide a link to a list of recent seed company designated SCA-tolerant/resistant hybrids below, but I recommend caution in evaluating information regarding sugarcane aphid tolerance/resistance. Access the full document for additional considerations. Foremost, at this time:

1) Assume all grain sorghum hybrids—even if designated tolerant/resistant to SCA—have some level of susceptibility (and all would be viewed as highly susceptible in some fields) to sugarcane aphid.
2) All grain sorghum hybrids must be scouted, and at this time the same SCA treatment thresholds apply to these hybrids as any other. No sorghum hybrid is immune to SCA. Some Texas farmers made the mistake of assuming too much about early purported tolerant hybrids for 2015, and they failed to treat SCA in timely fashion, or even scout their fields regularly if at all.

Dr. Ron Schnell, AgriLife cropping systems agronomist, College Station, and Dr. Bill Rooney, Texas A&M AgriLife Research sorghum breeder, College Station, both contribute further helpful comments in understanding how to properly assess the designation of specific grain sorghums as having substantial tolerance/resistance to sugarcane aphid. Together the we offer three “Bottom Lines” for potentially selecting a suitable grain sorghum hybrid for your farming conditions:

1) Texas sorghum producers should view all hybrids as susceptible at some level and follow standard scouting and treatment thresholds for every sorghum hybrid.
2) Many field reports of SCA field activity in different hybrids are simply observations that someone has seen tolerance at some point. It certainly doesn’t mean that you can ignore the SCA without implication.
3) Texas A&M AgriLife suggests producers consider planting adapted high-yielding grain sorghum hybrids then expect and plan to manage the sugarcane aphid, because even if you plant a tolerant/resistant hybrid, you likely still have to manage it and you may be giving up significant yield potential with an SCA-tolerant/resistant hybrid if it doesn’t yield well.

Read the full document for additional information on grain sorghum hybrid tolerance/resistance to sugarcane aphid, including:

• Understand the potential caveats of designated SCA-tolerant/resistant hybrids. Here are some questions you can ask seed companies regarding their hybrids:

1) “What hybrid(s) do you have with a proven SCA resistance gene in its parentage?”
2) “If you do, does that genetic background transfer actual hybrid resistance to SCA in the field?”
3) “What field evidence do you have for this hybrid’s substantial tolerance/resistance? Seedling tests? Field observations? Field insect counts? Yield data?”
4) “Is at least some of your field data from independent or external sources?” (If so, who?)
5) “How does the yield of your current SCA tolerant/resistant hybrid(s) compare to your company’s best grain sorghum hybrids?” (Agronomically, you want to understand the grain yield potential of good grain sorghum hybrids even if susceptible to SCA vs. tolerant/resistant hybrids. If there are significant yield differences be sure to ask/understand if those differences may be due to likely lower-yielding shorter maturity in a hybrid.)

• Seed company initial list of designated tolerant/resistant grain sorghum hybrids (summarized by United Sorghum Checkoff Program). Dr. Brent Bean, agronomist, USCP, has compiled an initial list (Dec. 17, 2015) of grain sorghum hybrids where each seed company has confirmed their designation of individual hybrids they believe demonstrate evidence of notable tolerance/resistance to sugarcane aphid. Review his additional comments and access the link to the current list found in the full version of this publication. Dr. Bean’s focus emphasizes potentially stronger SCA tolerance/resistance—the hybrids each company has the most confidence in. Hybrids that at this time are regarded as ‘moderately’ tolerant/susceptible are not included in the list.
• Current sugarcane aphid resources for Texas grain sorghum producers. This lists six Texas A&M AgriLife, USCP, and Texas Sorghum Association websites that maintain information different aspects of grain sorghum and sugarcane aphid.

The full text of this publication is available online at http://lubbock.tamu.edu (link is entitled ‘Grain Sorghum Hybrid Selection and Sugarcane Aphid 2016).

Calvin Trostle
Professor and Extension Specialist
Lubbock, TX
803.746.6101
ctrostle@ag.tamu.edu