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Tuesday, April 7, 2015

Sugarcane Aphid Overwintering Study, Hale County, Results

Sugarcane Aphid Overwintering Site – Hale County, Texas

                Today, Dr. Pat Porter, District 2 Entomologist, and I concluded the Sugarcane Aphid Overwintering Site Trial near Hale Center in Hale County.   I am happy to report that we found no surviving sugarcane aphids in the overwintering site today.  The site had been successfully infested with sugarcane aphids from sorghum last fall with a thriving and established population of aphids confirmed to be healthy within the predator exclusion cage area before the local killing freeze date last November.  All green Johnson grass shoots, crowns, actively growing leaves and stalks, plus most rhizomes were methodically checked above ground and below for the aphid with no survivors found. 
                Near and alongside the predator exclusion cage containing the artificially infested Johnson grass utilized for the trial were placed two temperature sensors.  One sensor was placed in the soil surface near the cage and the other at a depth of 4.5 inches alongside neighboring Johnson grass rhizomes.  The temperature recordings for this winter are:
4.5 inch depth: hours below 32 degrees = 8 (all on Dec. 31). Lowest temperature = 31.7 degrees. 

Soil surface: hours below 32 degrees = 1151. Lowest recorded temperature = 8.5 degrees.   There were 109 days between Nov. 5th (tent deployment) and today that had at least one hour at 32.0 degrees or below. The last freeze was March 27th at 5:00 am. 
The longest continual period at 32 degrees or below was 65 hours (Feb 26 – March 1). The next longest was 64 hours (Dec 29 – Jan 1). 

This is not to say that we will not see the sugarcane aphid in this area this season.  They could very easily migrate in annually, much like the fall armyworm or the sorghum midge, and are very likely to do so.  For now, we can feel as reasonably certain as one site can that this aphid did not overwinter on the High Plains.
Thanks to Dr. Pat Porter and Dr. Ed Bynum for all their assistance and expertise.  Good Luck,

Blayne Reed 

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