Cotton acreage in Alabama's coastal counties is rapidly increasing. The potential exists for planting 50,000 to 100,000 acres in this area if trends continue. High rainfall, averaging 65 to 70 inches per year, encourages weed germination and growth. This situation combined with inexperienced cotton producers offers the potential for poor weed control.

Cotton fields were surveyed before harvest in late season during 1991. A total of 16 fields were surveyed in four southern Alabama counties, two of which border Mobile bay. The survey technique consisted of counting mature weeds on either side of 10 feet of row at 20 sites in each field. Sites were randomly selected using a zig-zag pattern starting from a field border and walking down 10 paces then over 8 rows. Fields were selected based on vehicle odometer readings.

A total of 22 weed species were identified (Table 1). Prickly sida, large crabgrass, sicklepod, and annual morningglory represented the most common species; being found in 63, 69, 75, and 75 percent of the fields, respectively. Crowfootgrass and goosegrass were present in half the fields surveyed. Weeds present in the greatest densities include the species listed above and Florida pusley.

Bermudagrass and johnsongrass were perennials found in a small percentage of the fields surveyed. Yellow nutsedge was more common, occurring in 25 percent of the fields surveyed. None of these perennial weeds were observed in numbers large enough to be considered detrimental to cotton yields. Essentially all cotton in this area is currently grown using conventional tillage practices, which may help perennial weeds in check.

Redweed, Melochia corchorifolia, a species indigenous to coastal area of the southern states, was found in 3 percent of the fields surveyed.

The presence of uncontrolled annual grass species and Florida pusley in several of the fields surveyed may indicate that preplant incorporated herbicides which have activity on these weeds are either not being used or are being used at reduced rates. Another possible explanation is the rapid degradation of herbicides in the warm, humid environment of Alabama's coastal counties. In addition to the need for better annual grass control, sicklepod, annual morningglory, and prickly sida are broadleaf species which will require more attention.

County agents who cooperated in the conduction of this survey include Ed Tunnell, Mike Dennison, Dru Rush, and Mike Gamble.