Documentation of Weed Infestation Levels in Louisiana Cotton

Dearl E. Sanders


 
ABSTRACT

Cotton fields were surveyed in late season 1989, before harvest. Defoliated fields were selected whenever possible. A total of 57 fields were surveyed in the three cotton growing regions in Louisiana: Delta, Macon Ridge and Red River Valley. The number presented in tables 1, 2 and 3 represent mature weeds only. Therefore this survey reflects weeds that are not being controlled rather than the total number of species present. They survey should reflect weeds that are competitive with the crop season long.

The survey technique consisted of counting all mature weeds on two adjacent rows (80" wide) for 50 feet, or - total of 100 row feet. Four areas were randomly selected in each field for a total of 400 row feet in each field. Fields were randomly selected and were separated by a minimum of two miles.

A total of 23 weed species were identified. In general broadleaf weeds were more common in the Delta and Macon Ridge areas while grassy weeds were more common in the Red River area. Perennial vines were more common in the Delta and Macon Ridge areas than the Red River Valley.

In comparing this survey with the same survey conducted in 1986 there were several weeds found in 1989 that were not present in the 1986 survey. These weeds were confined to the extreme southern and of the Delta area where not cotton was around in 1986. When present these weeds such as wild poinsettia and itchgrass were present at high levels. The total number of morningglories present in 1989 were higher than in 1986. Other weed levels were comparable both years.



Reprinted from 1990 Proceedings: Beltwide Cotton Production Research Conferences pg. 357
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998