6000 University of Georgia Herbicide Programs for Tropical Spiderwort (Benghal Dayflower) Control in 2013 Cotton | UGA Cooperative Extension

A.S. Culpepper, J.T. Flanders and T.M. Webster

Tropical spiderwort is a noxious, exotic, invasive Figure 1. Newly emerged. weed that can spread quickly. Upon initial observation, tropical spiderwort appears to be a grass (Figure 1). While not a grass, it is a monocot (in contrast to broadleaf weeds, which are dicots) with leaves and stems usually fleshy and succulent. The stems will creep along the ground and root at the nodes. Vegetative cuttings from stems are capable of rooting and reestablishing following cultivation. Tropical spiderwort will produce seed above and
below ground (Figure 2).

Prior to glyphosate-resistant Palmer amaranth challenging our cotton industry, this weed was the most problematic weed of cotton. However, Roundup-based programs developed to control Palmer amaranth have indirectly controlled tropical spiderwort very effectively. During 2011/2012 with greater adoption of Liberty-based programs, tropical spiderwort became more problematic as Liberty is not effective in controlling this weed. A programs approach is needed for both Roundup and Liberty based systems. Tables 1 through 3 are suggestions for the management of tropical spiderwort in Georgia cotton. Refer to the most recent cotton production guide or pest control handbook for herbicide rates and proper cotton sizes at time of application.

Figure 1. Newly emerged spiderwort. Figure 2. Underground fruiting structures.

 


Table 1. Managing Tropical Spiderwort in Roundup Ready (RR) Cotton.1
Preemergence POST 1 POST 2 Layby Directed
Warrant2 + herbicides
appropriate for other weeds

Roundup
+
Staple, Dual Magnum3 or Warrant2

(Use Staple if spiderwort or Palmer amaranth are up)

Roundup
+
Dual Magnum3

Direx + MSMA

(Add Aim if spiderwort is greater than 3 inches; the addition of Dual Magnum3 or Warrant2 would improve residual control)

1 Deep turning the land will provide fair control of spiderwort
2 Apply Warrant no more than twice per season, once topically. Dual Magnum can be applied topically once per crop.
3Dual Magnum can be applied topically once per crop.


Table 2. Managing Tropical Spiderwort in GlyTol/Liberty Link Cotton.1
Preemergence POST 1 POST 2 Layby Directed
Warrant2 + herbicides
appropriate for other weeds

Liberty + Staple, Dual Magnum3 or Warrant2

OR

Roundup + Staple, Dual Magnum3 or Warrant2

Liberty + Staple, Dual Magnum3 or Warrant2

OR

Roundup + Staple, Dual Magnum3 or Warrant2

Direx + MSMA

(Add Aim if spiderwort is greater than 3 inches; the addition of Dual Magnum3 or Warrant2 would improve residual control)

Considerations for selecting POST 1 and 2 treatments:
1. Use Liberty instead of Roundup if Palmer amaranth has emerged.
2. With Liberty or Roundup: add Staple if spiderwort has emerged
but use Dual or Warrant if spiderwort has not emerged.

1 Deep turning the land will provide fair control of spiderwort
2 Apply Warrant no more than twice per season, once topically.
3Dual Magnum can be applied topically once per crop.

 

 

Table 3. Managing Tropical Spiderwort with Liberty Link Cotton. 1
Preemergence POST 1 POST 2 Layby Directed
Warrant2 + herbicides
appropriate for other weeds

Liberty + Staple, or Warrant2

(spiderwort emerged)

Liberty + Dual
Magnum

(before spiderwort emerges)

Direx + MSMA

(Add Aim if spiderwort is greater than 3 inches; the addition of Dual Magnum3 or Warrant2 would improve residual control)

Liberty + Dual Magnum3
or Warrant2

(spiderwort not emerged)

1 Deep turning the land will provide fair control of spiderwort
2 Apply Warrant no more than twice per season, once topically.
3Dual Magnum can be applied topically once per crop.



Status and Revision History
Published on Feb 04, 2008
Published on Jan 19, 2011
Published with Minor Revisions on Jan 03, 2012
Published with Minor Revisions on Feb 13, 2013
Published with Full Review on Mar 29, 2017

Faculty
Stanley Culpepper Professor - Extension Weed Scientist, Crop & Soil Sciences Ted Webster Cotton Workgroup Tim Flanders Retire Rehire ANR Agent, 00AC Southwest District 34BB
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