ABSTRACT
A study was initiated to examine potential interactions associated with thrips injured cotton and label specific Roundup Ultra applications. Experiments were conducted at the Ben Hur Research Farm, near Baton Rouge, LA in 1998 and 1999. The experimental design was a randomized complete block with a factorial arrangement of treatments. The first factor included simulated thrips injured terminals at the 1-leaf stage and a non-injured control. The second factor was early season cotton herbicide use strategies. Treatments included Prowl (0.75 lb ai/A) + Cotoran (1.2 lb ai/A) preemergence (PRE) or no PRE followed by (fb) sequential applications of Roundup Ultra (0.5 lb ai/A) at the cotyledon and 4-leaf stage fb Roundup Ultra (0.75 lb ai/A) early directed (EDIR); Prowl + Cotoran PRE or no PRE fb Roundup Ultra (0.75 lb ai/A) at the 4-leaf stage fb Roundup Ultra EDIR; Prowl + Cotoran PRE or no PRE fb Roundup Ultra (0.75 lb ai/A) at the 4-leaf stage fb Cotoran (1.0 lb ai/A) + MSMA (2.0 lb ai/A) EDIR; Prowl + Cotoran PRE fb Staple (1.0 oz ai/A) at the 4-leaf stage fb Cotoran + MSMA EDIR; and preemeregence treatment only. Application at the 4-leaf stage represents the early postemergence (POST) treatment while the sequential applications at cotyledon fb 4-leaf represents the late POST application. All treatments were applied with a CO2 backpack sprayer calibrated to deliver 15 gallons per acre. Plot size was 4 rows (38" spacing) x 40' with four replications. Data was collected on days to first square, height to node ratio at 2, 4, and 5 weeks after treatment (WAT), leaf area at 3 WAT, days to first bloom, and yield.
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