Eclipta Identification and Control in Peanut

Eric P. Prostko
Professor and Extension Agronomist – Weed Science

• Introduction
• Description
• Biology
• Control
• References
• Attention! Pesticide Precautions

Introduction

Figure 1. Eclipta infestation in peanut near Moultrie, Ga., 2003. (E.P. Prostko)

Eclipta (Eclipta prostrata formerly Eclipta alba) is a broadleaf weed that can occasionally be found in fields throughout the peanut belt. In Georgia, eclipta is not considered to be one of the most common weeds in peanut, but it can be very troublesome in years when environmental conditions (cool, wet) favor its development (Figure 1). Eclipta is considered to be one of the world’s worst weeds and has been reported to be a problem in 17 crops in 35 countries. Other names for eclipta include yerba-de-tago and false daisy.

Description

Eclipta plants can grow either prostrate (flat) or erect (upright) up to 36 inches tall (Figure 2). Seedling leaves are ovate to egg-shaped with short, toothed margins (Figure 3). Older leaves are opposite and lanceolate (long and narrow) with toothed margins (Figure 4). Stems are reddish-purple with short, flat, up-turned hairs (Figure 5). Eclipta has round flowers that are green early then white with short rays (Figure 6).

Figure 2. Eclipta line drawing from USDA-NRCS PLANTS Database/Britton, N.L. and A. Brown. 1913. Illstrated Flora of the Northern States and Canada. Vol. 3: 486.

Figure 3. Eclipta two-leaf seedling. (J.H. Brock)

Figure 4. Eclipta has opposite leaves with toothed margins. (E.P. Prostko)

Figure 5. Eclipta has hairy, reddish-purple stems. Flowers are green when immature. (E.P. Prostko)

Figure 6. Eclipta flower. (E.P. Prostko)

Biology

Like many other plants that have become weed problems, eclipta is not native to the United States. It was introduced from Asia. Eclipta is a member of the Compositae or Asteraceae plant family. This is the third most important plant family in terms of the number of weed species and includes plants such as common cocklebur (Xanthium strumarium), common ragweed (Ambrosia artemisiifolia), and bristly starbur (Acanthospermum hispidum).

Eclipta is a summer annual weed that has the potential to produce 17,000 seeds per plant (Figure 8). Eclipta seed can germinate over a wide range of soil temperatures (50 to 95 degrees F) and pH levels (5 to 8). Optimum temperature for germination is 95 degrees F. Eclipta germination is greater in moist soils, so it is most often found in poorly drained or low lying areas of a field and in years of excessive rainfall.

Figure 7. Eclipta in peanut. (E.P. Prostko)

Figure 8. Eclipta seed. (J.H. Brock)

Competition studies to assess the influence of eclipta populations on peanut yield have not been conducted at this time. However, some research has shown that the presence of eclipta in peanut can reduce yields more than 75 percent.

Eclipta can act as a host for Sclerotinia blight (Sclerotinia minor). Although this disease is not present in Georgia, it is common in many other peanut producing states such as North Carolina, Oklahoma, Texas and Virginia. Additionally, eclipta is an alternate host of the southern root-knot nematode (Meloidogyne incognita), which was identified in more than 65 percent of the soil samples analyzed in a recent University of Georgia survey.

Control

Soil-Applied Herbicides

Preplant-incorporated or preemergence applications of Strongarm (diclosulam) or a preemergence application of Valor (flumioxazin) provide good to excellent residual control of eclipta. Preemergence herbicides are most effective when followed by at least 0.5 inches of rainfall or irrigation within 7 to 10 days after application. Under extremely dense populations of eclipta, control from a soil-applied herbicide may need to be augmented with a sequential postemergence herbicide application.

Postemergence Herbicides

Postemergence herbicides that provide adequate control of eclipta include Cobra (lactofen), Basagran (bentazon), Storm (bentazon + acifluorfen), and Ultra Blazer (acifluorfen). These herbicides are most effective if applied to eclipta plants less than 2 inches in height. Postemergence herbicide applications made to eclipta greater than 2 inches often result in reduced control (Table 1).

References

Altom, J.V., R.B. Westerman, and D.S. Murray. 1995. Eclipta (Eclipta prostrata L.) control in peanuts (Arachis hypogaea L.). Peanut Science 22:114-120.

Altom, J.V, and D.S. Murray. 1996. Factors affecting eclipta (Eclipta prostrata) seed germination. Weed Technology 10:727-731.

Bailey, W.A., J.W. Wilcut, D.L. Jordan, C.W. Swann, and V.B. Langston. 1999a. Response of peanut (Arachis hypogaea) and selected weeds to diclosulam. Weed Technology 13:771-776.

Bailey, W.A., J.W. Wilcut, D.L. Jordan, C.W. Swann, and V.B. Langston. 1999b. Weed management in peanut (Arachis hypogaea) with diclosulam preemergence. Weed Technology 13:450-456.

Clewis, S.B., S.D. Askew, and J.W. Wilcut. 2002. Economic assessment of diclosulam and flumioxazin in strip- and conventional-tillage peanut. Weed Science 50:378-385.

Grichar, W.J. 1997. Influence of herbicides and timing of application on broadleaf weed control in peanut (Arachis hypogaea). Weed Technology 11:708-713.

Grichar, W.J., and A.E. Colburn. 1996a. Eclipta (Eclipta prostrata L.) control in peanuts (Arachis hypogaea L.) with soil-applied herbicides. Texas Journal of Agriculture and Natural Resources 9:97-104.

Grichar, W.J., and A.E. Colburn. 1996b. Postemergence control of eclipta (Eclipta prostrata L.) in peanuts (Arachis hypogaea L.). Texas Journal of Agriculture and Natural Resources 9:89-96.

Holm, L.G., D.L. Plucknett, J.V. Pancho, and J.P. Herberger. 1977. The World’s Worst Weeds: Distribution and Biology. University Press of Hawaii. Honolulu. 609 pp.

Price, A.J. and J.W. Wilcut. 2002. Weed management with diclosulam in strip-tillage peanut (Arachis hypogaea). Weed Technology 16:29-36.

Sholar, J.R. and J. N. Nickels. 1999. Eclipta (Eclipta prostrata) control programs in peanut. Proceedings of the Southern Weed Science Society 52:63.

USDA, NRCS. 2002. The PLANTS Database, Version 3.5. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Trade and brand names are used only for information. Cooperative Extension, University of Georgia College of Agricultural and Environmental Sciences does not guarantee nor warrant published standards on any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others which may also be suitable.

Attention! Pesticide Precautions

• It is the responsibility of the pesticide user to observe all directions, restrictions and precautions on pesticide labels. It is dangerous, wasteful and illegal to do otherwise.
• Store all pesticides in original containers with labels intact and behind locked doors. KEEP PESTICIDES OUT OF THE REACH OF CHILDREN.
• Use pesticides at correct label dosage and intervals to avoid illegal residues or injury to plants and animals.
• Use pesticides carefully to avoid drift or contamination of non-target areas.
• Surplus pesticides and containers should be disposed of in accordance with label instructions so contamination of water and other hazards will not result.
• Follow directions on the pesticide label regarding restrictions as required by State or Federal Laws and Regulations.
• Avoid any action that may threaten an endangered species or its habitat. Your county extension agent can inform you of endangered species in your area, help you identify them and, through the Fish and Wildlife Service Field Office, identify actions that may threaten endangered species or that habitat.