Tropical spiderwort emerges later in the growing season than most weeds. That means that planting cotton early would give the crop a head start before tropical spiderwort takes off. These are some of the findings of Agricultural Research Service (ARS) agronomist Theodore Webster, Tifton, GA.
Tropical spiderwort (Commelina benghalensis L.) has become a serious weed because of changes in cropping and production systems, like the planting of Roundup Ready crops. Tropical spiderwort has a natural tolerance to glyphosate, the active ingredient in Roundup. According to Webster, it also tolerates other common herbicides, and those that control it best increase production costs significantly.
A native of Africa and south Asia, tropical spiderwort is unique in the plant world because it produces both aerial and underground flowers, and both types form seeds. It wasn't considered a troublesome weed in Georgia until 1999, according to Webster. Annual control efforts now cost the Georgia cotton industry more than $1.2 million.
In Georgia, planting cotton in April and early May helps get a jump on tropical spiderwort. Typically, cotton is planted in late May and into June, the edge of the planting window for cotton in southern Georgia.