PARTHENIUM HYSTEROPHORUS L.
R. Labrada

Characterisation

Parthenium weed (Plates 4c., 4d.), also known as white top, whitehead, congress grass or carrot grass, is an erect annual herb with alternate, deeply-dissected leaves, growing up to 2 m tall with much branched inflorescences bearing white flower heads and numerous obovoid, smooth and black achenes.

The seeds of parthenium do not germinate immediately after ripening, as the achenes first need to disperse and release several inhibitors of germination (Picman and Picman 1984; Kohli et al. 1985; Kumari and Kohli 1987). The germination of parthenium reaches a maximum 1-6 months after the achenes ripen. The seeds are not able to germinate in soil below a depth of 5 cm. In the Caribbean area parthenium flowers 30-45 days after germination and the whole plant cycle is completed within about 5 months, with a single plant producing an average of 810 flower heads (Labrada 1988). A photoperiod of 13 hours and warm conditions are conducive to flowering (Williams and Groves 1980).

Distribution/importance. Parthenium is a native of tropical America and was introduced into Africa, Asia and Oceania in cereal and grass seed shipments from U.S.A. during the 1950s.

Parthenium is wide-spread in grassland, fruit tree orchards and arable land in neutral and acid soils. In India the weed is considered a major problem (Gupta and Sharma 1977; Shelke 1984); in Central America and the Caribbean area parthenium mainly thrives in areas repeatedly treated with paraquat or with certain soil-acting herbicides selectively used in vegetable and legume crops such as trifluralin, diphenamid and others (Labrada 1990).

The allelopathic potential of parthenium weed results from the release of phytotoxic substances such as, ferulic, caffeic, vanillic, chlorogenic, p-coumaric and p-hydroxybenzoic acids, parthenin, ambrosin and coronopilin, which inhibit the germination and growth of several crop plants and multi-purpose trees (Basak 1984; Jarvis et al. 1985; Dharmaraj and Ali 1985; Srivastava et al. 1985; Dayama 1986; Swaminathan et al. 1990) and also cause allergic eczematous contact dermatitis and respiratory problems in humans and livestock (Auld and Medd 1987).

Parthenium is also a host of several pests and diseases harmful to various crops. Reciprocal infection of Xanthomonas campestris pv. phaseoli between parthenium and bean plants has been established. Infection occurred with beans becoming infected at the pre-flowering and pod formation stages (Ovies and Larrinaga 1988).

Control strategies

In infested crop areas deep ploughing during the land preparation can reduce the stand of parthenium weed. In small areas hand hoeing during the early growth stages prevents flowering. Hoeing mature plants is ineffective because of regrowth from crown buds (Gupta and Sharma 1977).

In India, in heavy infested areas, replacement of parthenium has been achieved through the use of plants of Cassia spp. (Joshi 1991). Such a practice consists in manual removal of parthenium plants and subsequent seeding of Cassia plants (C. sericea or C. uniflora Mill.), population size of which increased with time in relation to that of parthenium. Two years later Cassia:parthenium ratio was higher than 21:1 (Mahadevappa and Ramaiah 1990).

Biological control of parthenium weed is already practiced in Australia through the use of the stem-galling moth, Epiblema strenuana (Lepidoptera: Tortricidae). The insect has a relatively high reproduction in short periods of time and its effectiveness has been validated in the central highlands of Queensland (McFadyen 1985). There are some other potential bioagents such as the leaf-feeding chrysomelid, Zygogramma bicolorata (Coleoptera: Chrysomelidae) and the stem-boring weevil Listronotus setosipennis (Coleoptera: Curculionidae). All these organisms originate from Brazil and Mexico, and require evaluation in countries infested with parthenium weed.

Another on-going development on biological control of parthenium is the use of the rust fungus Puccinia abrupta var. partheniicola. Uredospore suspensions from 3-week old pustules have been applied to parthenium foliage and a consistent control effect has been achieved (Parker 1989). This rust fungus is now being evaluated for development as a mycoherbicide.

Parthenium weed is not controlled by several well known herbicides such as paraquat (Njoroge 1991), trifluralin, diphenamid, napropamide and the acetanilides, alachlor, metolachlor and propachlor (Labrada 1990). This author has observed that in citrus, coffee and banana plantations treated repeatedly with paraquat parthenium has become the predominant species within one year. Similar infestations have ocurred in vegetable and legume fields treated for several years with trifluralin. These incidences of apparent resistance of parthenium to herbicides illustrate the need to use mixtures or sequences of herbicides against this weed.

There are several selective herbicide treatments effective for the control of parthenium weed (Table 1). Their implementation in small farm areas will depend on several socio-economic factors of the affected site.

In some situations it is useful to determine the economical threshold of parthenium in affected crop areas as an aid to decision-making on the need for costly chemical control. Threshold data have been established in several crops (Table 2). If parthenium is not controlled at the indicated density and crop period, unavoidable yield loss will occur and the weed seed bank will be increased.

Table 1. Herbicides for the control of Parthenium hysterophorus.

Table 2 Economic threshold of Parthenium hysterophorus in different crops

from Labrada and Morales (1986); Paredes and Labrada (1986); Paredes et al. (1990).

Auld B.A. and R.W. Medd 1987. Weeds, an illustrated botanical guide to the weeds of Australia. Inkata Press, Melbourne-Sydney 255 pp.

Basak S.L. 1984. Parthenium - a big threat to agriculture and health in 1980s. Indian Agriculturist 28:137-143.

Dayama O.P. 1986. Allelopathic potential of Parthenium hysterophorus L. on the growth, nodulation and nitrogen content of Leucaena leucocephala. Leucaena Research Reports 7:36-37.

Dharmaraj G. and A.M. Ali 1985. Allelopathic potential of parthenium (Parthenium hysterophorus L.) extracts. Abstracts Annual Conference Indian Society Weed Science, Tamil Nadu Agricultural University p 46.

Gupta O.P. and J.J. Sharma 1977. El peligro del partenium en la India y posibles medidas de control del mismo. Boletin Fitosanitario FAO 25:112-117.

Jarvis B.B., N.B. Pena, M.M. Rao, R.S. Comezoglu, T.F. Comezoglu and N.B. Mandava 1985. Allelopathic agents for Parthenium hysterophorus and Baccharis megapotamica. In "The Chemistry of Allelopathy, biochemical interactions among the plants", American Chemical Society, pp 149-159.

Joshi S. 1991. Biological control of Parthenium hysterophorus L. (Asteraceae) by Cassia uniflora Mill. (Leguminosae), in Banglore, India. Tropical Pest Management 37:182-184.

Kohli R.K., Anita Kumari and D.D. Saxena 1985. Auto and teletoxicity of Parthenium hysterophorus L. Acta Universitatis Agriculturae, Brno, A (Fac. Agronomy) 33:253-263.

Kumari A. and R.K. Kohli 1987. Autotoxicity of ragweed parthenium (Parthenium hysterophorus). Weed Science 35:629-632.

Labrada R. 1988. Complemento al estudio biológico de Parthenium hysterophorus L. Resumenes IX Congreso ALAM, julio 26-30, Maracaibo, Venezuela.

Labrada R. 1990. El manejo de malezas en áreas de hortalizas y frijol en Cuba. X Congreso ALAM, La Habana, abril 1-14, vol. II:1-16.

Labrada R. and R. Morales 1986. Umbral económico de Parthenium hystrophorus L. en frijol y soya. Resumenes VIII Congreso ALAM, Guadalajara, p 88.

Mahadevappa M. and H. Ramaiah 1990. Pattern of replacement of Parthenium hysterophorus plants by Cassia sericea in waste lands. Indian Journal of Weed Science 20:83-85.

McFadyen R.E. 1985. The biological control programme against Parthenium hysterophorus in Queensland. Proceeding VI Symposium Biological Control Weeds (19-25 august, 1984), Vancouver pp 789-796.

Njoroge J.M. 1991. Tolerance of Bidens pilosa L. and Parthenium hysterophorus L. to paraquat (Gramoxone) in Kenya. Kenya Coffee 56:999-1001.

Ovies J. and Loretta Larrinaga 1988. Transmisión de Xanthomonas campestris pv. phaseoli mediante un hospedante silvestre. Ciencia y Técnica Agricultura, Protección Plantas 11:23-30.

Paredes E. and R. Labrada 1986. Umbral de daños de Parthenium hysterophorus en plantación de pimiento y siembra directa de tomate. Resumenes VIII Congreso ALAM, Guadalajara, p 37.

Paredes E., E. Perez, F. La O and A. Suey 1990. Umbrales de daño económico de Parthenium hysterophorus L. en ajo (Allium sativus L.) y cebolla (Allium cepa L.). Resumenes X Congreso ALAM, La Habana, vol I:78.

Parker H. 1989. Biological control of Parthenium hysterophorus using two rust fungi. Proceedings VII Symposium Biological Control Weeds, Rome pp 531-538.

Picman J. and A.K. Picman 1984. Autotoxicity in Parthenium hysterophorus and its possible role in control of germination. Biochemical Systematics and Ecology 12:287-292.

Shelke D.K. 1984. Parthenium and its control - a review. Pesticides 18:51-54.

Srivastava J.N., J.P. Shukla and R.C. Srivastava 1985. Effect of Parthenium hysterophorus L. extract on the seed germination and seedling growth of barley, pea and wheat. Acta Botanica Indica 13:194-197.

Swaminathan C., R.S. Rai and K.K. Smesh 1990. Allelopathic effects of Parthenium hysterophorus on germination and growth of a few multi-purpose trees and arable crops. International Tree Crops Journal 6:143-150.

Williams J.D. and R.H. Groves 1980. The influence of temperature and photoperiod on growth and development of Parthenium hysterophorus L. Weed Research 20:47-52.