Status of parthenium weed (Parthenium hysterophorus L.) and its control options in Ethiopia

Parthenium (Parthenium hysterophorus L.) is an invasive herbaceous weed which belongs to the family Compositae. It is believed to have originated in tropical America and now occurs widely in Asia, Australia, Southern and east Africa. Parthenium has been observed to grow on road sides, gardens, waterways, in grasslands and crop fields both during the crop season and after harvest, as long as enough moisture is available. In Ethiopia it is believed to have been introduced in the 1970s and currently covering almost all parts of the country causing up to 97% yield reduction in crop fields and 100% reduction in forage crops. The weed has become a problem for range, forest and crop lands. It grows in any soil type and in a wide range of habitats and is also known to affect animal and human health. It causes loss of bio diversity and presently it was recorded as an invasive alien weed species in Ethiopia. Suggested control measures include hand pulling, mowing and the use of herbicides. Hand pulling and mowing, however, have limited value because of the enormous amount of labor required and the sensitivity of humans to allergens produced by the weed. If herbicides are used, multiple applications are necessary. As well, appropriate herbicides are not available in all areas where the weed is a problem. Small-scale farmers may not be able to invest in management options for parthenium especially for pasture, fallow, wasteland, grazing land and road sides. Biological control using insect pests and plant pathogens in an integrated parthenium management system is one solution but not well reviewed.