Weed Control for Growing Sorghum in Puerto Rico

Abstract

Herbicides 2-chloro-4,6-bis(isopropylamino)-s-triazine (Propazine), 2- chloro-4-ethylamme-6-isopropylamino-s-triazine (Atrazine) and 3-(3-4-dichlorophenyl)- l, 1-dimethylurea (Diuron) were evaluated on sorghum (Sorghum bicolor (L.) Moench.) var. SA 406 at the Federal Experiment Station, Mayagüez, Puerto Rico. Applied as a pre-emergence spray, both Propazine and Atrazine at 3 lb./A. controlled broadleaf weeds and grasses, and were more effective than Diuron for control of broadleaf weeds in the initial test. Propazine was less injurious to sorghum than Atrazine. Effectiveness of Propazine was greater during the dry season (with supplemental irrigation) than during the wet season. Hand-weeded sorghum yielded significantly more fodder than plots treated with Propazine at 1 and 3 lb./A. during the wet season, but not during the dry season. Oats (Avena sativa (L.)) grew without apparent injury from herbicide residues when planted in plots 6 months after treatment with Propazine at rates of 1 and 3 lb./A. Propazine used at 2 to 3 lb./A. appears to be a safe and economical method of weed control in sorghum for the Tropics where soil type, rainfall, weed species, etc., are similar to those described herein.