Field survey on parthenium was conducted at East shewa Zone of Oromiya Regional State, Ethiopia during 2008 cropping season.  The objectives of the study was to assess the weed flora composition and plant species that are growing in copetation with parthenium to use those plants as potential biological management options under field condition. Assessment of weed flora composition was carried out in five Kebeles (Farmers Association) of Boset District East Shewa Zone of Oromiya Regional State, Ethiopia. Data on the species composition were recorded and samples of weed flora compositions were collected. The result showed a total of eighty five different herbaceous plant species that were collected and recorded in 63 genera and 24 families. Poaceae (21), Asteraceae (11), Fabaceae (7) and Convolvulaceae (7) were by far the richest taxa and accounted together (55 %) of the entire flora of the study area. The major plant species having higher dominance value were Parthenium hysterophorus (25.6), Cassia tora (6.07), Argemone mexicana (5.83), Xanthium strumarium (4.53), Digitaria abyssinica (3.02) and Cyperus rotundus (2.86). Similarity index values of the species composition among different kebeles ranged from 65% to 78% which indicating that weed species compositions in these locations were similar. The diversity and evenness of species declined with increasing spread of parthenium which suggests negative influence that parthenium had on the status of species diversity in the studied area. In conclusion the selected plant species that were found competitive with parthenium based on their abundance and dominance values were Argemone mexicana, Cassia tora, and Xanthium strumarium which were suggested for detailed competition experiment in order to determine their competitiveness with P. hysterophorus and will be used for biological management of it.

Crenate broomrape, Orobanche crenata Forskal belongs to the family Orobanchaceae. It is a root holoparasitic weed devoid of chlorophyll and entirely dependent on host plants for its growth requirement. This parasite considerably infects plant species of the families Leguminosae, Apiaceae, and Asteraceae in highly infested drier and warmer areas of the world. It is well-known for its devastating effects on cool-season food legumes especially on faba bean (Vicia faba L.) and for threatening the livelihood of subsistence farmers. Yield losses of infected crops reach up to 100% depending on the level of infection by the parasitic weed. The long-term impact of the parasite is even more serious than its short-term effects as its numerous minute seeds are easily spread using different mechanisms and persist in the soil for up to 20 years. Besides, its management is difficult as no single method proved to be effective, economical, and complete in managing the weed. This review article gives an overview of information on the biological characteristics and harmful effects of crenate broomrape and summarizes scientifically proven management techniques for its effective management. Different approaches should be validated, demonstrated, and scaled for wider uses to manage crenate broomrape sustainably and boost the host crop productivity. Therefore, besides narrowing the knowledge gaps on the weed biology more strengthened efforts in searching for host plant resistance and/or tolerance based integrated management approaches by considering socio-economic and ecological conditions of faba bean growers are found paramount importance.

Parthenium is an exotic invasive weed that originated in South America, and has formed severe infestations in Ethiopia. This weed is known to be host to various micro-organisms such as the rust pathogen Puccinia abrupta var. partheniicola that may be used as a component of integrated parthenium weed management. Field surveys were conducted in 2008 and 2009 cropping seasons in eastern Ethiopia to determine distribution, incidence, and severity of the rust (P. abrupta var. partheniicola) on this weed. In addition, the effect of this pathogen on morphological parameters of parthenium was studied both in the field and in the greenhouse at the Plant Protection Research Center, Ambo. A total of 218 fields were surveyed in four districts (Chiro, Gemechis, Kuni and Tullo) of Western Hararghe Zone, eastern Ethiopia. All the fields surveyed were infected with the pathogen, indicating that the disease was widely distributed in the zone. The incidence of rust in the surveyed area ranged from 25 to 74% while severity ranged from 18 to 55%. The highest (74%) and the lowest (25%) disease incidence were recorded in Tullo and Chiro, respectively, while the highest (55%) and the lowest (18%) disease severities were encountered at Gemechis and Chiro, respectively. Altitude had significant effect on both disease parameters (p ≤ 0.05). The effect of this pathogen on morphological parameters of parthenium under field conditions was found to be significant (p ≤ 0.05) at all locations. The effect of the rust on parthenium dry matter and seed production was significant (p ≤ 0.05) at all locations. Also, the effect of the rust on morphological parameters of parthenium in the greenhouse was significant (p ≤ 0.05). In addition, there was significant variation in the number of rust pustules per leaf, leaf senescence, and number of leaves attacked per plant, disease incidence and severity both at 14 and 21 days after inoculation. In the greenhouse, comparison of isolates from Ambo, Kuni, and Tullo showed significant effect while isolates from Chiro and Gemechis performed poorly for all the studied morphological parameters of parthenium. This study indicated that P. abrupta var. partheniicola has the potential to reduce morphological parameters as well as dry matter and seed production capacity of parthenium weed. It also elucidated the presence of variation in aggressiveness of the isolates. However, more extensive studies need to be undertaken at molecular level to utilize this pathogen in combination with other host-specific insects and pathogens after importation and release, as a component of integrated parthenium weed management in Ethiopia.

Invasive alien weed species; are non-indigenous species that have adverse economic, environment and ecological effects on habitats where they have been introduced, either accidentally or deliberately, outside their normal past or present distribution. The objective of this study was to determine the distribution and abundance of emerging invasive weeds in West Shewa and East Wollega Zones of Western Oromia. The biophysical survey was conducted by stopping along main and sub-roads accessible for, vehicle at 8 to10km interval. At each stop a 20m by 20m area was used to determine distribution and abundance of the invasive weeds. Five major emerging invasive weeds i.e Senna occidentalis, Senna didymobotrya, Xanthium spinosum and Carduus spp, Cirsium spp were identified as, important emerging invader species in the study area. Infestation of these weeds was mostly observed on roadsides, around human habitations, in pasture and waste lands and even crop fields. The extent of distribution varied among habitat and locations surveyed, ranging from none to abundant infestation of the alien weed species.

Sorghum bicoloris one of the most important cereals in the world and a staple crop for smallholder famers in sub Saharan Africa. However approximately 20% of sorghum yield is annually lost on the African continent due to infestation with the root parasitic weedStriga hermonthica. Existing Striga management strategies often show an inconsistent to low efficacy. Hence, novel and integrated approaches are needed as an alternative strategy. Here, we demonstrate that the soil microbiome suppresses Striga infection in sorghum. We associate this suppression with microbiome-mediated induction of root endodermal suberization and aerenchyma formation, and depletion of haustorium inducing factors (HIFs), root exudate compounds that are critical for the initial stages of Striga infection. We further identify microbial taxa associated with reduced Striga infection with concomitant changes in root cellular anatomy and differentiation as well as HIF degradation. Our study describes novel microbiome-mediated mechanisms of Striga suppression, encompassing repression of haustorium formation and induction of physical barriers in the host root tissue. These findings open new avenues to broaden the effectiveness of Striga management practices.