eturn to table of contents The plant may have uneven and/or poor head development and emergence, poor grain set, potentially increased stalk lodging, and harvest issues. Yield loss in sorghum can be severe with cases of 100% loss reported. ALTERNATE HOSTS Sugarcane aphids need living host plants to persist. In addition to sorghum, they can feed on shattercane (Sorghum bicolor), Johnsongrass (Sorghum halapense), as well as volunteer sorghum plants. Aphids also overwinter on these same plant species. In Mexico, the sugarcane aphid has been found colonizing barnyard grass (Echinochloa crus-galli). SCOUTING FOR SUGARCANE APHID Scouting should begin a few weeks after sorghum emergence. Scout at least once per week until aphids are found, then increase frequency to two field visits per week. In four or five areas within the field, inspect the underside of an upper leaf and a lower leaf for aphid presence. When populations begin to build, honeydew will be present on the top side of leaves. Take notes on the number of aphids present in each area. Several southern universities recommend an action threshold of 50 to 125 or more aphids per leaf on 25% or more of the plants. Understanding Differences in Hybrid Tolerance Sorghum hybrids vary in their ability to tolerate sugarcane aphid feeding. Significant work is underway with third party collaborators and at DuPont Pioneer to understand sorghum hybrid tolerance to sugarcane aphids. Pioneer ® hybrids 83P17 and 83P56 are known to possess at least some degree of aphid tolerance. However, tolerance is not the same as immunity, and tolerant hybrids must be scouted and sprayed if populations reach the action threshold. Contact your DuPont Pioneer field team for the latest information on hybrid results. Best Management Practices Best management practices include removing volunteer sorghum plants, using tolerant sorghum hybrids, utilizing high quality seed treatments, maintaining good grass weed management, scouting, and using insecticides, if needed. Here is a brief checklist: 1. Control volunteer sorghum to remove source of early infestation. 2. Plant a sorghum hybrid with aphid tolerance. 3. Use an effective insecticide seed treatment. 4. Plant early. 5. Scout fields early and weekly. 6. Apply an approved insecticide when the action threshold is reached. Avoid pyrethroid insecticides, which are harmful to beneficial insecticides and may cause aphid populations to rebound rapidly. 7. Consider using a harvest aid when sorghum nears maturity (25% grain moisture in the lower portion of the head) to kill and dry down the crop. Sooty mold on sorghum resulting from a heavy infestion of sugarcane aphid. Tractor in Central Mexico after traveling through an aphidinfested sorghum field. SUGARCANE APHID MANAGEMENT Insecticides for Sugarcane Aphid Several insecticides are labeled for use on sorghum in the U.S. Insecticide trials conducted by Texas A&M University have shown that Sivanto 200 SL insecticide (flupyradifurone) (Bayer CropScience) has provided significant reductions in aphid populations up to two weeks after application. Transform insecticide (sulfoxaflor) (Dow AgroSciences) was previously used in some states, but its registration was canceled by the EPA in November 2015. Existing inventories of sulfoxaflor may not be sold and distributed to end-users; however, some states are pursuing an emergency exemption (Section 18) from the EPA. When applying insecticides by ground equipment, University of Arkansas recommends that insecticides be applied in 10 gallons of water per acre. Growers should consult their Cooperative Extension Service for a current list of registered chemicals in their respective states and updated results on the efficacy of sugarcane aphid insecticides. Read and follow all label directions before applying an insecticide. 162 Plot in Central Mexico showing tolerant sorghum hybrids in the back compared to a susceptible hybrid in the front. ACKNOWLEDGMENTS Thanks to Dr. Robert Bowling, Texas A&M AgriLife, for providing information and insect close-up photograph. Field photos of sugarcane aphids on plant leaves, tolerant vs. non-tolerant plants, and tractor are courtesy of DuPont Pioneer Mexico Agronomy team.
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