Photographer: Sekh Sayantan Affiliation: Burdwan Eco Garden Source: www.bugwood.org Copyright: CC BY 3.0 US
Leaves are alternate, lily-like, 1.2-2.8 in. (3-7 cm) long and often have reddish hairs towards the tip. Aboveground flowers are very small with relatively large lilac to blue petals and are present from the spring into the fall. Underground flowers, which grow on burrowing rhizomes, are white and very small.
Tropical spiderwort forms, dense, pure stands, smothering out other plants, especially low-growing crops. It has been reported recently as a problem in cotton in Alabama. In pastures, it grows rapidly over desirable grasses and legumes, competing with them for light and nutrients. In rice and other lowland crops it may be almost subaquatic withstanding flooding and waterlogged conditions, but they can also be found in cultivated lands, field borders, gardens, grasslands, roadsides, and waste places, and can become the dominant species in pastures. In Georgia, it is the most troublesome weed of cotton and third most troublesome weed of peanut crops.
The tropical spiderwort is an herbaceous, creeping annual which becomes perennial depending on moisture conditions. The plants reproduce by seeds, stolons, and rooting at nodes of stems. One plant can produce as many as 1600 seeds.
The path of introduction into the United States is unclear. It was described as a new species in Miami Springs, Florida in 1962; however, it was later realized to be an invasive species that entered Florida in the mid 1930's. In 1983, the U.S. Department of Agriculture designated tropical spiderwort as a Federal noxious weed. In Georgia, it has become very problematic and is the most troublesome weed of cotton and third most troublesome weed of peanut crops.
Native Origin: Asia and Africa
U.S. Habitat: Tropical spiderwort invades areas with moist soil including roadsides, grasslands and other disturbed areas. It grows in a wide range of habitats, varying from water-saturated to dry soils; grows rapidly and forms dense mats at the nodes under optimum conditions. Commelina benghalensis is found in arable and plantation crops, and non-crop lands. In Asia and Africa it is reported as the main weed in rice, tea and coffee fields. It is also a common weed in sugarcane and maize. It has become the most problematic weed of cotton and third most troublesome weed of peanut crops in Georgia.
U.S. Present: AL, CA, FL, GA, HI, LA, NC and WV
For distribution map provided by the USDA PLANTS database click here
False dayflower (Commelinantia anomala) or spreading dayflower (C. diffusa) it can be differentiated by having a spathe sealed along two edges to form a triangular pocket; it also has broader leaves (length 2-3 times width), stolons with underground flowers, and leaf sheaths with reddish-brown-tipped hairs.
Property managers and cooperators may use these strategies:
Cultural Control: Plants readily root at the nodes of the creeping stems, especially when cut or broken, making these weeds difficult to control in field areas. Sections on the soil surface root readily during rainy weather or in the shade of crop plants.
Chemical Control: University of Florida tests conducted in 2000 showed that Command and Spartan used in combination or alone were effective April to early June, but effectiveness trailed off later in the season. Methods Development has found that 46 brands of herbicide are labeled for use on dayflower. However, farmers in Florida have not been able to control tropical spiderwort effectively with chemicals. Control with herbicides is difficult because many seeds germinate after the initial flush of summer weeds and part of the seeds are produced underground.
Biological Control: None is known.
USE PESTICIDES WISELY: Always read the entire pesticide label carefully, follow all mixing and application instructions and wear all recommended personal protective gear and clothing. Mention of pesticide products on this web site does not constitute endorsement of any material
References
Culpepper, A. S., Webster, T. M., & Flanders, J. T. (2005). Tropical spiderwort identification and control in Georgia field crops.
Culpepper, A. S., Flanders, J. T., York, A. C., & Webster, T. M. (2009). Tropical Spiderwort (Commelina benghalensis) Control in Glyphosate-Resistant Cotton1.
Domestic Programs Pest Evaluation. Arthur E. Miller, USDA-APHIS-PPQ, AERO, Raleigh, NC. November 26, 2001.
Faden, R. B. (1993). The misconstrued and rare species of Commelina (Commelinaceae) in the eastern United States. Annals of the Missouri Botanical Garden, 208-218.
McFarlin, J. B. (1935). Flora of the central portion of the Lake Region District of Florida.
USDA-APHIS. (2000). Federal Noxious Weed List.
Webster, T. M., Burton, M. G., Culpepper, A. S., York, A. C., & Prostko, E. P. (2005). Tropical Spiderwort (Commelina benghalensis): A Tropical Invader Threatens Agroecosystems of the Southern United States 1. Weed technology, 19(3), 501-508.
Internet Sources
http://www.texasinvasives.org/plant_database/detail.php?symbol=COBE2
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