Quantification of cotton plant growth response to cotton fleahopper infestations

Cotton fleahopper (Pseudotomoscelis seriatus Reuter) is an important early-season cotton pest in Texas. Cotton fleahopper adults and nymphs feed upon cotton squares, inflicting heavy early-season square loss, and potentially altering the cotton plant growth pattern. The growth responses of cotton cultivars to various levels of cotton fleahopper injury are yet to be clearly characterized. In this study, the plant growth responses of two commercially available cotton cultivars (DP 161B2RF and FM 9063B2F) to cotton fleahopper injury were evaluated versus control plants. Control plants received no insect augmentation. Cotton fleahoppers were laboratory-reared on green beans to thirdand fourth-instar nymphs and then carefully released in cotton plant terminals at the rate of 4-6 nymphs per plant to create the “high” cotton fleahopper infestation treatment. Cotton plant growth, development, and yield parameters were then monitored. Cotton plant height, root length, numbers of nodes, leaves, fruits and root-shoot biomasses were recorded from treated and control plants. DP 161B2RF plants were significantly taller than those of FM 9063B2F. Early-season fleahopper-induced fruit losses did not affect the cotton plant growth. In both study years, no significant plant height differences were observed between cotton fleahopper-infested and control plots. Unusually high temperatures and low precipitation in 2011 complicated comparisons between years. No significant plant biomass differences between control and fleahopper-infested plants were observed in 2010. However, in 2011, total plant biomass was significantly higher in fleahopper-infested plots than in control plots. In both cultivars, lint yield data suggest that cotton plants were able to compensate for 15-20% of cotton fleahopperinduced early-season fruit loss.