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Several species of thrips are known to infest cotton seedlings in the United States and constitute one of the most common insect pest challenges for growers. The species complex, species abundance, extent of crop injury, and impact on lint yield varies widely across the cotton states. Cotton seedlings are most susceptible to thrips injury during the first 4 to 5 weeks after plant emergence. Feeding by thrips results in distortion, malformation and tearing of seedling leaves, reduced leaf area and plant height, reduced root growth, and injury to or death of the apical meristem, the latter of which leads to excessive vegetative branching. Plant maturity (i.e., fruit production) can be delayed and in extreme cases, losses of as much a 30-50% of lint yield potential have been reported. To date, no varieties of cotton have resistance to thrips, so controls are based solely on insecticide applications. Treatment thresholds and control practices (e.g., insecticide seed treatments, in-furrow or foliar applied insecticides) vary widely across cotton states. This article provides a brief summary of the various species of thrips present in U.S. cotton, their plant host range and injury to cotton, a general description of thrips biology, and management practices currently available to growers. |
