1) Evaluate the effectiveness of two herbicide scenarios on weed control and lint yield.

2) Evaluate a new plant growth regulator against mepiquat chloride.

Methodology: Paymaster 2326 BG/RR and Fibermax 989 BG/RR were planted on May 6, 2002 in three replications (16 rows x 250’ long) in a subsurface drip irrigated field. The seasonal herbicide scenarios were as follows: 1) Prowl (pre-plant incorporation) followed by a broadcast application of Roundup Ultra Max (post-emergence) followed by post-directed spray of Roundup Ultra Max and 2) Broadcast application of Roundup Ultra Max (post-emergence) followed by post-directed spray of Roundup Ultra Max. Plant growth regulator (PGR) treatments were 1) Pix Plus/BAS, a new PGR, and 2) mepiquat chloride, the original PIX. Weed control was observed during the growing season and lint yield was determined after harvest. A total of 15.1 inches of water was applied through the sub-surface drip irrigation system.

Results: Due to very low rainfall and subsurface drip irrigation, pigweed pressure was light and both the Prowl + Roundup UltraMax and the Roundup UltraMax only scenarios provided effective season-long weed control (Table 1.). Similar cotton yields were produced with either PGR treatment. FiberMax 989 BG/RR produced the highest lint yield at 2069 lb./ac.