Cotton Leaf Grade As Influenced by Cotton Defoliation and Varieties

Defoliation of cotton, Gossypium hisrutum L., prior to harvest is a critical step in maintaining cotton fiber quality, especially minimizing the presence of cotton plant material (leaf, bracts, etc) in the module and ultimately in the lint after ginning.  Plant material (leaf, bract, etc.) in ginned cotton is quantified using a leaf grade scale (1-7) and is quantified by the cotton classing office.  High leaf grade values will result in dockage to the producer. Cotton classed at the Corpus Christi Classing Office has shown a steady increase in cotton leaf grades over the past 10 years.  Many cotton producers contribute this increase in leaf grade trends to hairier leaf cotton varieties and increased use of desiccation products to defoliate cotton.  To address these questions, multiple trials were initiated in 2010 and 2011 in South Texas to determine the impact of cotton variety and defoliation treatments individually, and the interaction between these two factors.