Incidence of Spider Mites in South Texas Cotton Fields

The presence/absence of spider mites was surveyed in four locations of south Texas from Progreso (Hidalgo Co.) to Bishop (Nueces Co.). This transect is approximately 125 miles from north to south.  Spider mite densities were estimated from 26 April to 25 July, 2011.  In each location, the percentage of plants infested by spider mites was determined sampling 50 leaves in each border and interior plants (10 leaves/plant).  Spider mites appeared early in the season in Progreso, Harlingen and Raymondville compared with Bishop.  The percentages of plants infested by spider mites were higher in Harlingen and Raymondville than Bishop.  Similar trends were observed on their presence through the growing season for the same locations.  The Progreso cotton field presented lower number of spider mites versus other fields.  This field was isolated and surrounded by the Rio Grande River and onion fields whereas the rest of fields have sorghum or corn plants nearby that may have contributed to initial spider mite populations.