Observations on the current status of Orobanche and Striga problems worldwide

Abstract

Species of Orobanche and Striga are among the most damaging parasitic weed species worldwide, but there are few reliable statistics on the full extent of the economic losses they cause. The distribution, host range and economic importance of the major species of Orobanche and Striga are briefly summarised. A review of literature over the period since 1991 suggests that many million hectares are infested and that the losses amount to $ US billions annually. Unfortunately there are almost no fully reliable figures on which to base these figures precisely. Meanwhile, there is little evidence of any significant change in intensity, range or losses caused over this period. Any reduction in the importance of these damaging weeds is sporadic, and alleviation of the problems is mostly localised. Furthermore, while the importance of Orobanche species may be broadly static, Striga species on cereals continue to become more serious in many countries owing to continued loss of soil fertility. It is suggested that new techniques may be needed for measurement of the extent of losses caused by these genera and their economic impact. There is continued urgency to develop control measures appropriate to the farming systems involved, and to reduce the risk of spread of both groups of parasite to new areas.

Molecular mechanism of strigolactone perception by DWARF14

“…In addition, SLs stimulate the germination of root parasitic weeds 3,4 that cause devastating crop damage 5 and induce hyphal branching in symbiotic arbuscular mycorrhizal fungi that promote the growth of host plants by capturing essential inorganic nutrients from the soil [6][7][8] . Owing to the importance of SLs in agriculture, the mechanism and signal transduction pathway of SLs have been extensively researched to provide a perspective on the broader SL functions.…”

“…S2). The direct interaction between D14 and SLs was determined using a non-equilibrium gel-permeation technique and [5, Fig. 2a), a radioactive SL.…”

Striga

“…This region has been also reported to be the native place of domesticated sorghum [Sorghum bicolor L.]. The distribution of Striga in relation to ecological zones in Africa and India indicates that sorghum and pearl millet are the most parasitized hosts (Ramaiah, 1984;Parker, 2009;. Thus, over 50 million ha of the arable farmland under cereals in subSaharan Africa are reported to be infested with Striga (Westwood et al, 2010).…”

“…Striga species, known as witchweeds, are one of the most troublesome and damaging weeds in the world (Parker, 2009). They belong to the Orobanchaceae family (ex Scrophulariaceae) and are obligate root hemi-parasitic plants (Olmstead et al, 2001;Tank et al, 2006).…”

“…However, these strategies are expensive methods and are not generally available to smallholder farmers in Striga-prone zones of Africa and Asia. In these regions, the Striga problem is, in general, associated with low economic resources, low soil fertility, marginal environments with continued cereal monoculture and newly infested areas regrettably due to various human and agricultural activities (Oswald, 2005;Rodenburg et al, 2005;Parker, 2009).…”