A replicated small plot field trial to measure the response of cotton, Gossypium hirustum L., to applications of Messenger, harpin, was conducted during the 2000 growing season near Inverness, MS. Applications of 2.23 ounces of Messenger were made at various combinations of 3 leaf, pinhead square, 2 weeks after pinhead square, first bloom and 3 weeks after first bloom timings. No differences were observed in percentage of nitrogen, phosphorus and potassium in the leaves at mid-bloom. Measurements of plant growth, fruiting positions, fiber characteristics, lint yield and population levels of reniform nematodes, Rotylenchulus reniformis, produced variable results. Extreme heat and drought may have masked the full effects of Messenger.