Friday, May 29, 2015

Brief Update from The Coast; New Map Format

Dr. Robert Bowling, Extension Entomologist in Corpus Christi, makes the sugarcane aphid distribution maps. This year he is color coding the affected counties to reflect sugarcane aphid densities. Green indicates populations that are below the 50 aphids per leaf threshold, yellow indicates populations at threshold (50 - 125 per leaf), and red indicates large populations.


Dr. Bowling reports that SCA populations in south Texas have been much lighter than expected. This may be the result of heavy and persistent rain across large portions of Texas, but particularly south Texas. Natural enemies were present throughout the winter, and particularly lady beetles (adults and larvae, especially Scymnus lady beetle larvae) were observed among SCA at several overwintering sites. Parasitoids (one Braconid wasp but mainly Aphelinidae species) and predators like syrphid fly and lacewing larvae are abundant. Sorghum planting dates in south Texas are scattered all over the calendar. Some fields in the LRGV were planted near the end of January and the last fields were planted around the first of May. These late planted fields may be vulnerable to a wide range of pests; rice stink bug populations were very large in some wheat fields and remain active on various weed hosts. Fall armyworm populations are variable and trap collections, approximately 30 per week in the Corpus Christi area, suggest very low populations in south Texas at this time. Corn earworm, Helicoverpa zea, is practically non-existent right now (fewer than 10 moths per week over the past  4 weeks).  Sorghum midge is not much of an issue right now but has a high probability of being an issue in some of the late, late planted sorghum.

Dr. Bowling reports that SCA populations on sorghum along the Coastal Bend are starting to increase this week but populations remain very low as of this report.  Winged SCA have been found over the past three weeks but persistent rains may be hampering their ability to colonize fields.