Post-Harvest Control of
Tropical Spiderwort in Field Corn
Figure 1. Tropical spiderwort control
with 2,4-D followed by 2,4-D
8581
88 85
0
20
40
60
80
100
1 2 3 4
Weeks After POST2
Co
ntr
ol
- %
2,4-D amine @ 1.5 pt/A
bc abab a
Figure 2. 2,4-D followed by 2,4-D
Untreated 2,4-D @ 1.5 pt/A
POST1 + POST 2
($14.41/A)POST1: 8-10” tall COMBE
POST2: 2 weeks later
Photo 1 week after POST2
Figure 3. Tropical spiderwort control with
2,4-D followed by Gramoxone Inteon
95
83 86 84
0
20
40
60
80
100
1 2 3 4
Weeks After POST2
Co
ntr
ol
- %
2,4-D amine @ 1.5 pt/A
Gramoxone Inteon @ 1 qt/A + COC @ 1% v/v
a
a aa
J.T. Flanders1* and E.P. Prostko2 1Berrien County Extension Coordinator - Nashville
2Extension Weed Specialist - Tifton
INTRODUCTION:
Tropical spiderwort (TSW) has become one of the most
troublesome weeds in Georgia. Since the majority of
TSW does not emerge until after June 1, it is rarely an
in-season field corn weed problem. However, TSW
becomes a major concern after corn harvest since it can
produce seed in approximately 40 days after
emergence. Limited studies have been conducted on
the post-harvest control of TSW.
MATERIALS AND METHODS:
A field trial was conducted at the Mark Whigam Farm in
Grady County to evaluate the effect of various herbicide
treatments for the control of TSW. Combinations of 2,4-D
amine 3.8SL(1.5 pt/A), Aim 2EC (1.5 oz/A), and
Gramoxone Inteon 2SL (1 qt/A) were applied after corn
harvest. A crop oil concentrate (Agri-Oil) was included with
all Gramoxone Inteon and Aim treatments @ 1% v/v.
POST1 applications were made to 8-10” tall TSW. POST2
applications were applied 2 weeks after the POST1
applications (2-4” TSW re-growth). Traditional small plot
techniques were utilized. All herbicide treatments were
applied with a back-pack sprayer calibrated to deliver 15
GPA using 11002DG flat-fan nozzle tips. The treatments
were arranged in a randomized complete block design with
four replications. Visual control ratings were obtained on a
weekly basis using a scale of 0 to 100% (0 = no control,
100 = complete control). All data were subjected to ANOVA
and means separated using Duncan’s Multiple Range Test
at P = 0.10. Mean comparisons are appropriate within time
after application.
RESULTS:
Single applications of 2,4-D, Aim, or Gramoxone Inteon
were not effective in controlling TSW (data not reported).
At 1 week after the POST2 treatments, the split application
of 2,4-D provided less control than 2,4-D followed by
Gramoxone or Gramoxone followed by Gramoxone. At 4
weeks after the POST2 treatments, the split application of
Aim provided less control than the other split treatments.
No other statistical differences in control were observed.
Figure 4. 2,4-D followed by Gramoxone
Inteon
Untreated 2,4-D @ 1.5 pt/A (POST1)
Gramoxone Inteon @ 1 qt/A + COC (POST2)
($19.90/A)POST1: 8-10” tall COMBE
POST2: 2 weeks later
Photo 1 week after POST2
Figure 5. Tropical spiderwort control with
2,4-D followed by Aim
93
8185 83
0
20
40
60
80
100
1 2 3 4
Weeks After POST2
Co
ntr
ol
- %
2,4-D amine @ 1.5 pt/A
Aim @ 1.5 oz/A + COC @ 1% v/v
ab
aba ab
Figure 6. 2,4-D followed by Aim
Untreated 2,4-D @ 1.5 pt/A (POST1)
Aim 2EC @ 1.5 oz/A + COC (POST2)
($20.90/A)POST1: 8-10” tall COMBE
POST2: 2 weeks later
Photo 1 week after POST2
Figure 7. Tropical spiderwort control with
Gramoxone Inteon followed by
Gramoxone Inteon
95
83 8581
0
20
40
60
80
100
1 2 3 4
Weeks After POST2
Co
ntr
ol
- %
Gramoxone Inteon @ 1 qt/A + COC @ 1% v/v
a
a a abc
Figure 8. Gramoxone Inteon followed
by Gramoxone Inteon
Untreated Gramoxone Inteon @ 1 qt/A + COC
POST1 + POST2
($25.40/A)POST1: 8-10” tall COMBE
POST2: 2 weeks later
Photo 1 week after POST2
Figure 9. Tropical spiderwort control with
Aim followed by Aim
93
79 7671
0
20
40
60
80
100
1 2 3 4
Weeks After POST2
Co
ntr
ol
- %
Aim @ 1.5 oz/A + COC @ 1% v/v
ab
ab abde
Figure 10. Aim followed by Aim
Untreated Aim 2EC @ 1.5 oz/A + COC
POST1 + POST2
($27.40/A)POST1: 8-10” tall COMBE
POST2: 2 weeks later
Photo 1 week after POST2
CONCLUSIONS:
Growers who want to manage TSW after corn harvest with
herbicides should consider the following treatments:
1) 2,4-D followed by 2,4-D, Aim, or Gramoxone Inteon
2) Split applications of Gramoxone Inteon
3) Split applications of Aim
This research was partially supported through a grant provided by the Georgia
Agricultural Commodity Commission for Corn
