Characterization of Cotton Crop Response to Western Flower Thrips Injury and Its Management in Texas High Plains Cotton

Abstract: The western flower thrips, Frankliniella occidentalis Pergande, is a serious pest on seedling cotton in the Texas High Plains and other regions of the U.S. cottonbelt. Thrips are an early season pest which can cause severe damage to seedling cotton. First three weeks of seedling stage is important because thrips can cause significant damage during this period when plants are 1-3 true-leaf stage. The ultimate goal of the research project was to develop new economic thresholds for thrips based upon plant response characteristics, validating or revising the current Texas High Plains thrips treatment threshold recommendations, and precisely characterizing the cotton crop response to various levels of thrips injury at different cotton seedling ages.

In the greenhouse study, 0, 0.5, 1 and 2 thrips per plant were released at 1- to 2- true-leaf stage. Significantly higher thrips densities were observed from treatments where 1 or 2 thrips were released per seedling compared to 0.5 and control. Visual ranking values of plants from thrips densities 0 and 0.5 were significantly superior compared to that from thrips densities 1 and 2. Similar densities were achieved in field cages via thrips release in No-Thrips® cages to compensate for 80% field mortality. Significant numbers of thrips were recovered from all thrips-augmented treatments, with lowest numbers recovered from control plants. Leaf area was significantly higher in uninfested control compared to those in thrips augmented treatments. Thrips densities of 0.5, 1, and 2 per plant at early seedling stage all reduced lint yield significantly compared to that in uninfested control plots. Similar densities were achieved in field cages via thrips release in No-Thrips^® cages to compensate for 80% field mortality. Thrips densities of 0.5, 1, and 2 per plant at early seedling stage all reduced lint yield significantly compared to that in uninfested control plots.