Thursday, August 3, 2017

Aphids Unaffected by High Plains Rains, New Counties Added to the Map

The reports from downstate that discussed the relatively wimpy punch of sugarcane aphid this year, and the association of rain with that lack of punch, gave us hope that this week's rains on the High Plains would have the same effect. Unfortunately, I have to report that we have seen no evidence that the rainfall slowed down the aphids.

We have been monitoring several fields in Crosby and Lubbock counties for some time, and this week the aphid numbers are higher than last week - considerably higher in some places. At the Lubbock Research and Extension Center where we have had almost 2 inches of rain in a week over two events, the aphids have now exceeded the treatment threshold on pre-boot through soft dough sorghum.

There is still a chance that rain and high humidity will kick off the fungi that kill sugarcane aphids, but as yet there is no evidence this is happening. Even with the more humid days we have experienced of late, our average humidity is well below that in South Texas where the fungi were given credit for reducing aphid numbers.

The good news is that there are relatively fewer aphids coming in now than in past years, so fields are building toward treatment thresholds in a softer manner. The larger colonies on High Plains plants are beginning to generate winged aphids.

Brent Bean, Agronomist for Sorghum Checkoff, reported sugarcane aphids on sorghum in Parmer County today.  Deaf Smith County was also added to the map today. DeBaca County in east central New Mexico also has confirmed sugarcane aphids.  The official map has been updated to reflect these discoveries.