Sorghum Tips

2016 Sugarcane Aphid Watch–South and Central Texas

This tip was provided by:

Robert Bowling, (361) 265-9201, Robert.bowling@ag.tamu.edu, Assistant Professor, Extension Entomology, Corpus Christi
IPM Extension agents Stephen Biles (Port Lavaca), Danielle Sekula-Ortiz (Weslaco) and Kate Harrell (Wharton)

South and Central 

2016 Sugarcane Aphid Watch 

Another season is upon us as farmers have begun seeding sorghum in the Lower Rio Grande Valley and Coastal Bend of Texas. Sorghum has emerged in the Valley and in some areas around Corpus Christi. Warm and dry conditions have made possible the early start to the season, especially when compared with the 2015 cropping year. How might these conditions influence sugarcane aphid infestations in sorghum?

Sugarcane aphid reproduction is favored by hot and dry conditions. Currently, sugarcane aphids have already been observed overwintering on Johnsongrass as far north as Hill County (Waxahachie).  Numerous cast skins in aphid colonies have been observed around Corpus Christi up to Austin County suggesting that sugarcane aphids are maturing and producing offspring. It is possible they will start moving to sorghum early this season.  What is the path forward to protect the crop from sugarcane aphid injury in 2016?

Our full first-of-the-season report on SCA for South & Central Texas is online at http://ccag.tamu.edu/sorghum-insect-pests/  Several additional SCA resources are also there including the Scout Card for use in field ID of SCA and the all-important Quick Aphid Checker to rapidly estimate the number of aphids per leaf.

Here are some additional points from our full write-up:

  • Know the aphid.  Use a magnifying lens for ID.  If honeydew is observed, look at the underside of the leaf above.  If the sugarcane aphid is found on Johnsongrass or volunteer sorghum start scouting sorghum shortly after plants have emerged.
  • Start scouting sorghum early! If the planting seed was treated with an insecticide seed treatment (which AgriLife generally recommends; the cost is spread out over many acres), the crop should be protected for 30 to 45 days.
  • Several grain sorghum hybrids have been identified as ‘tolerant’ to sugarcane aphid.  Be aware, however, that tolerance does not equate to immunity and all sorghum fields should be scouted for sugarcane aphid.  Ask your preferred seed company for their best tolerant material.
  • In-season insecticide options for managing sugarcane aphid are limited.  Sivanto (Bayer) is currently the most effective product labeled on sorghum and is safe to beneficial insects.
  • Carrier total volume of water applied to the field is important!  Complete coverage of all foliage is critical for maximum performance of an insecticide targeting the aphid.  Do not apply less than 10 gallons of final volume of spray solution per acre if treating with a ground rig and no less than 5 gallons per acre if applying by air (even if the product is labeled for 3 gal/acre or less).
  • DON’T BE COMPLACENT!  Last year in South/Central Texas was cool and wet.  SCA’s growth was slow thus insect predators to maintained sugarcane aphid populations at a low level.

Next Sorghum Tip (late Mrach):  Guidelines for sugarcane aphid in the Texas High Plains, where thresholds are lower, even just the Presence of SCA in the field (in contrast to a set number of SCA per leaf for South & Central Texas).